Rotor Balancing \u2014 Procedures, Types & Standards \u2014 Vibromera<\/title>\n<meta name=\"description\" content=\"Complete guide to rotor balancing: static vs. dynamic (single-plane and two-plane), the influence coefficient method, step-by-step field procedure, ISO 21940 \/ ISO 1940-1 tolerances, correction techniques, and worked examples with the Balanset-1A.\">\n<meta name=\"keywords\" content=\"rotor balancing, dynamic balancing, static balancing, single-plane balancing, two-plane balancing, influence coefficient method, trial weight, correction weight, field balancing, in-situ balancing, vibration reduction, ISO 21940, G-grade, unbalance correction, Balanset\">\n<meta name=\"author\" content=\"Vibromera\">\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large\">\n\n\n\n\n\n\n\n<meta property=\"og:type\" content=\"article\">\n<meta property=\"og:title\" content=\"Rotor Balancing \u2014 Procedures, Types & Standards (Complete Guide)\">\n<meta property=\"og:description\" content=\"Static vs. dynamic balancing, step-by-step influence coefficient method, ISO 21940 tolerances, correction techniques, and field balancing with Balanset-1A.\">\n<meta property=\"og:url\" content=\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/\">\n<meta property=\"og:site_name\" content=\"Vibromera \u2014 Vibration Analysis & Balancing Equipment\">\n<meta property=\"og:locale\" content=\"en_US\">\n<meta property=\"og:image\" content=\"https:\/\/vibromera.eu\/wp-content\/uploads\/rotor-balancing-og.jpg\">\n<meta property=\"article:publisher\" content=\"https:\/\/vibromera.eu\/\">\n<meta property=\"article:section\" content=\"Glossary\">\n<meta property=\"article:tag\" content=\"Rotor Balancing\">\n<meta property=\"article:tag\" content=\"Dynamic Balancing\">\n<meta property=\"article:tag\" content=\"Field Balancing\">\n<meta name=\"twitter:card\" content=\"summary_large_image\">\n<meta name=\"twitter:title\" content=\"Rotor Balancing \u2014 Static vs. Dynamic, Procedures & ISO Tolerances\">\n<meta name=\"twitter:description\" content=\"Step-by-step balancing guide: influence coefficient method, single-plane and two-plane procedures, ISO 21940 G-grade tolerances.\">\n<meta name=\"geo.region\" content=\"EU\">\n<meta name=\"geo.placename\" content=\"Porto, Portugal\">\n<meta name=\"geo.position\" content=\"41.1579;-8.6291\">\n<meta name=\"ICBM\" content=\"41.1579, -8.6291\">\n<script type=\"application\/ld+json\">\n{\n \"@context\":\"https:\/\/schema.org\",\n \"@graph\":[\n {\n \"@type\":\"TechArticle\",\n \"@id\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/#article\",\n \"headline\":\"Rotor Balancing: Procedures, Types & Standards \u2014 Complete Guide\",\n \"description\":\"Comprehensive guide to rotor balancing: static vs. dynamic, single-plane and two-plane procedures, the influence coefficient method, ISO 21940\/1940-1 tolerances, field balancing techniques, and practical worked examples.\",\n \"author\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\n \"publisher\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\",\"logo\":{\"@type\":\"ImageObject\",\"url\":\"https:\/\/vibromera.eu\/wp-content\/uploads\/vibromera-logo.png\"}},\n \"mainEntityOfPage\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/\",\n \"datePublished\":\"2024-02-20\",\n \"dateModified\":\"2026-02-07\",\n \"inLanguage\":\"en\",\n \"about\":[\n {\"@type\":\"Thing\",\"name\":\"Rotor Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Dynamic Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Field Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Vibration Reduction\"}\n ]\n },\n {\n \"@type\":\"FAQPage\",\n \"@id\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/#faq\",\n \"mainEntity\":[\n {\"@type\":\"Question\",\"name\":\"What is rotor balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Rotor balancing is the process of improving the mass distribution of a rotating body so that its centre of mass coincides with its geometric axis of rotation. This minimises centrifugal forces, reducing vibration, bearing loads, noise, and energy consumption. Correction is done by adding or removing weight at specific locations and angles, guided by vibration measurements and phase analysis.\"}},\n {\"@type\":\"Question\",\"name\":\"What is the difference between static and dynamic balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Static (single-plane) balancing corrects a single heavy spot \u2014 the centre of mass is displaced from the axis but the inertia axis stays parallel. Suitable for narrow disc-like rotors (L\/D < 0.5). Dynamic (two-plane) balancing corrects both force and couple unbalance \u2014 the general case where the inertia axis is skewed. Required for elongated rotors. Most real rotors need dynamic balancing.\"}},\n {\"@type\":\"Question\",\"name\":\"How does the trial weight (influence coefficient) method work?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Step 1: Measure initial vibration (amplitude + phase). Step 2: Attach a known trial weight at a known angle. Step 3: Measure new vibration. Step 4: The vector difference between runs reveals how that location influences vibration \u2014 the influence coefficient. Step 5: Software calculates the exact correction mass and angle to cancel the original unbalance. Step 6: Remove trial weight, install correction, verify.\"}},\n {\"@type\":\"Question\",\"name\":\"When should I use single-plane vs. two-plane balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Single-plane: rotors with L\/D < 0.5 (narrow, disc-like) \u2014 fan impellers, pulleys, narrow grinding wheels, flywheels. Two-plane: rotors with L\/D > 0.5 (elongated) \u2014 motor armatures, multi-stage pump shafts, paper rolls, cardan shafts. When in doubt, use two-plane \u2014 it handles both static and couple unbalance.\"}},\n {\"@type\":\"Question\",\"name\":\"What ISO standard applies to rotor balancing tolerances?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 21940-11 (formerly ISO 1940-1) defines the G-grade balance quality system. G 6.3 is the standard for most industrial fans, pumps, and motors. G 2.5 for turbines and critical machinery. The formula U_per = (9549 \u00d7 G \u00d7 M) \/ n gives permissible residual unbalance in g\u00b7mm. ISO 14694 extends this to fan-specific BV categories.\"}},\n {\"@type\":\"Question\",\"name\":\"Can I balance a rotor without removing it from the machine?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes \u2014 this is called field balancing or in-situ balancing. A portable balancer like the Balanset-1A uses vibration sensors and a tachometer mounted on the installed machine. The trial-weight influence coefficient method determines correction without needing a dedicated balancing machine. This saves hours of disassembly\/reassembly downtime.\"}},\n {\"@type\":\"Question\",\"name\":\"What are common correction methods?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Adding mass: clip-on weights, bolt-on weights, weld-on weights, epoxy\/putty, set screws. Removing mass: drilling, milling, grinding. The choice depends on rotor design, operating environment, and whether the correction is permanent or for trim balancing. Weight splitting distributes correction between adjacent accessible positions when the exact angle is not reachable.\"}},\n {\"@type\":\"Question\",\"name\":\"How do I know if vibration is caused by unbalance?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Unbalance produces vibration at exactly 1\u00d7 RPM (the running speed) in the radial direction. In an FFT spectrum, a dominant 1\u00d7 peak with stable phase angle is the classic signature. If vibration is at 2\u00d7, 3\u00d7, or other multiples, other faults (misalignment, looseness, bearing defects) are more likely. 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h2{font-size:24px}}\n@media(max-width:480px){.hero h1{font-size:24px}.quick-nav a{padding:12px 12px;font-size:13px}.benefits-grid{grid-template-columns:1fr}}\n@media print{.quick-nav,.shop-cta,.toc-sidebar{display:none}}\n<\/style>\n<\/head>\n<body>\n\n<header class=\"hero\">\n <div class=\"hero-inner\">\n <div class=\"breadcrumb\"><a href=\"https:\/\/vibromera.eu\/\">Home<\/a> \u2192 <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary<\/a> \u2192 Rotor Balancing<\/div>\n <h1>Rotor Balancing \u2014 <span>Procedures, Types<\/span> & Standards<\/h1>\n <div class=\"canon-badge\"><span style=\"font-size:14px;\">\ud83d\udccc<\/span> Canonical Reference Article \u2014 vibromera.eu<\/div>\n <p class=\"subtitle\">The complete guide to balancing rotating machinery: static vs. dynamic (single-plane and two-plane), the influence coefficient method, ISO 21940 tolerances, field balancing, and correction techniques.<\/p>\n <\/div>\n<\/header>\n\n<nav class=\"quick-nav\">\n <div class=\"quick-nav-inner\">\n <a href=\"#types\">\u2696 Static vs. Dynamic<\/a>\n <a href=\"#procedure\">\ud83d\udd27 Procedure Steps<\/a>\n <a href=\"#benefits\">\ud83d\udcc8 Benefits<\/a>\n <a href=\"#definition\">\ud83d\udcd0 Overview<\/a>\n <a href=\"#method\">\u2699 Method<\/a>\n <a href=\"#when-to-balance\">\ud83c\udfaf When to Balance<\/a>\n <a href=\"#correction\">\ud83d\udd29 Correction<\/a>\n <a href=\"#field-balancing\">\ud83c\udfed Field Balancing<\/a>\n <a href=\"#standards\">\ud83d\udccf Standards<\/a>\n <a href=\"#cases\">\ud83d\udcdd Cases<\/a>\n <a href=\"#faq\">\u2753 FAQ<\/a>\n <\/div>\n<\/nav>\n\n\n<section class=\"section-bg\" id=\"types\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>Static vs. Dynamic Balancing<\/h2>\n <p>The two fundamental balancing types \u2014 determined by rotor geometry and the type of unbalance present<\/p>\n <\/div>\n <div class=\"type-grid\">\n <div class=\"type-card static\">\n <div class=\"tc-icon\">\ud83d\udccd<\/div>\n <div class=\"tc-title\">Static (Single-Plane)<\/div>\n <div class=\"tc-subtitle s\">One correction plane<\/div>\n <div class=\"tc-body\">Corrects <strong>static unbalance<\/strong> \u2014 the rotor's centre of mass is displaced from the rotation axis but the inertia axis remains parallel. Equivalent to a single \"heavy spot.\" Detectable without rotation (gravity reveals it on knife-edges).<\/div>\n <div class=\"tc-specs\">\n <div class=\"tc-spec\"><span class=\"spec-label\">Planes<\/span><span class=\"spec-value\">1 correction plane<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Sensors<\/span><span class=\"spec-value\">1 vibration sensor + 1 tachometer<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Rotor shape<\/span><span class=\"spec-value\">Disc-like, L\/D < 0.5<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Examples<\/span><span class=\"spec-value\">Fan impellers, pulleys, grinding wheels, narrow flywheels<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Balanset mode<\/span><span class=\"spec-value\">F2 \u2014 Single-Plane<\/span><\/div>\n <\/div>\n <\/div>\n <div class=\"type-card dynamic\">\n <div class=\"tc-icon\">\ud83d\udcab<\/div>\n <div class=\"tc-title\">Dynamic (Two-Plane)<\/div>\n <div class=\"tc-subtitle d\">Two correction planes<\/div>\n <div class=\"tc-body\">Corrects <strong>dynamic unbalance<\/strong> \u2014 the general case combining static and couple components. The inertia axis is neither parallel to nor intersecting the rotation axis. Only detectable while spinning. Creates both force and rocking-moment vibration.<\/div>\n <div class=\"tc-specs\">\n <div class=\"tc-spec\"><span class=\"spec-label\">Planes<\/span><span class=\"spec-value\">2 correction planes<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Sensors<\/span><span class=\"spec-value\">2 vibration sensors + 1 tachometer<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Rotor shape<\/span><span class=\"spec-value\">Elongated, L\/D > 0.5<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Examples<\/span><span class=\"spec-value\">Motor armatures, pump shafts, paper rolls, cardan shafts<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Balanset mode<\/span><span class=\"spec-value\">F3 \u2014 Two-Plane<\/span><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"table-wrap\">\n <div class=\"table-title\">\ud83d\udcca Single-Plane vs. Two-Plane \u2014 Decision Guide<\/div>\n <div class=\"table-scroll\"><table>\n <thead><tr><th>Criterion<\/th><th><span class=\"tag sp\">Single-Plane<\/span><\/th><th><span class=\"tag tp\">Two-Plane<\/span><\/th><\/tr><\/thead>\n <tbody>\n <tr><td>Unbalance type corrected<\/td><td>Static only<\/td><td>Static + couple (dynamic)<\/td><\/tr>\n <tr><td>Rotor geometry<\/td><td>L\/D < 0.5 (disc-like)<\/td><td>L\/D > 0.5 (elongated)<\/td><\/tr>\n <tr><td>Number of runs<\/td><td>2 (initial + trial)<\/td><td>3\u20134 (initial + 2 trials, or cross-coupling)<\/td><\/tr>\n <tr><td>Sensors required<\/td><td>1 accelerometer + tacho<\/td><td>2 accelerometers + tacho<\/td><\/tr>\n <tr><td>Bearing vibration pattern<\/td><td>In-phase at 1\u00d7<\/td><td>Phase varies (not in-phase, not 180\u00b0)<\/td><\/tr>\n <tr><td>Typical rotors<\/td><td>Fan impellers, pulleys, grinding wheels<\/td><td>Motors, pumps, rolls, turbines, shafts<\/td><\/tr>\n <tr><td>ISO plane recommendation<\/td><td>Narrow rotors per ISO 1940-1 \u00a74.3<\/td><td>Standard for all elongated rotors<\/td><\/tr>\n <tr><td>Balanset-1A mode<\/td><td class=\"mono\">F2<\/td><td class=\"mono\">F3<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section class=\"section-bg alt\" id=\"procedure\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>The Balancing Procedure<\/h2>\n <p>Influence coefficient (trial weight) method \u2014 the standard approach for field and shop balancing<\/p>\n <\/div>\n <div class=\"steps-grid\">\n <div class=\"step-card\"><div class=\"step-num\">1<\/div><div class=\"step-icon\">\ud83d\udcca<\/div><div class=\"step-title\">Initial Measurement<\/div><div class=\"step-desc\">Run the machine at operating speed. Measure vibration amplitude (mm\/s) and phase angle (\u00b0) at each bearing. This is the <strong>baseline<\/strong> \u2014 the unbalance signature. Record in Balanset-1A.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">2<\/div><div class=\"step-icon\">\u2696\ufe0f<\/div><div class=\"step-title\">Attach Trial Weight<\/div><div class=\"step-desc\">Stop the machine. Attach a known trial weight at a known angular position in the correction plane. Mass should produce a noticeable but not dangerous vibration change (10\u201330% of initial).<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">3<\/div><div class=\"step-icon\">\ud83d\udcc8<\/div><div class=\"step-title\">Trial Run<\/div><div class=\"step-desc\">Run again at the same speed. Measure new vibration amplitude and phase. The <strong>vector difference<\/strong> between initial and trial runs is caused solely by the trial weight.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">4<\/div><div class=\"step-icon\">\ud83e\uddee<\/div><div class=\"step-title\">Calculate Correction<\/div><div class=\"step-desc\">Software computes the <strong>influence coefficient<\/strong> \u2014 how much vibration change per unit mass at that location. Then calculates exact correction mass (g) and angle (\u00b0) to cancel the original unbalance.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">5<\/div><div class=\"step-icon\">\ud83d\udd29<\/div><div class=\"step-title\">Install Correction<\/div><div class=\"step-desc\">Remove trial weight. Attach the calculated permanent correction weight at the prescribed angle. For two-plane: repeat steps 2\u20134 for the second plane (Balanset-1A solves both simultaneously).<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">6<\/div><div class=\"step-icon\">\u2705<\/div><div class=\"step-title\">Verify<\/div><div class=\"step-desc\">Final run to confirm residual vibration is within tolerance. Compare measured residual against ISO 1940-1 U<sub>per<\/sub> limit. Balanset-1A displays pass\/fail and generates a balance report.<\/div><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section class=\"section-bg\" id=\"benefits\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>Why Balance? \u2014 The Benefits<\/h2>\n <p>Unbalance is the #1 source of vibration in rotating machinery. Correction delivers measurable returns.<\/p>\n <\/div>\n <div class=\"benefits-grid\">\n <div class=\"benefit-card\"><div class=\"ben-icon\">\u2699\ufe0f<\/div><div class=\"ben-title\">Bearing Life<\/div><div class=\"ben-desc\">Unbalance forces go directly to bearings. 50% vibration reduction \u2192 up to 8\u00d7 bearing life extension.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\udee1\ufe0f<\/div><div class=\"ben-title\">Reliability<\/div><div class=\"ben-desc\">Lower vibration \u2192 less fatigue on seals, shafts, couplings, and foundations. Fewer breakdowns.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\udd07<\/div><div class=\"ben-title\">Noise<\/div><div class=\"ben-desc\">Vibration is the primary noise source. Balanced machines run significantly quieter.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\u26a1<\/div><div class=\"ben-title\">Energy<\/div><div class=\"ben-desc\">Energy wasted on vibration and heat is recovered as useful work. Measurable efficiency gain.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\uded1<\/div><div class=\"ben-title\">Safety<\/div><div class=\"ben-desc\">Severe unbalance can cause catastrophic failure. Balancing prevents vibration-induced accidents.<\/div><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<main class=\"main-content\" id=\"definition\">\n <div class=\"container\">\n <div class=\"content-layout\">\n <article class=\"article-content\">\n\n <h2>What is Rotor Balancing?<\/h2>\n <div class=\"info-box\" style=\"border-left-color:var(--navy);background:var(--beige-light);\">\n <div class=\"box-title\" style=\"font-size:16px;\">Quick Answer<\/div>\n <p style=\"font-size:15px;\"><strong>Rotor balancing<\/strong> is the process of improving the mass distribution of a rotating body so that its centre of mass coincides with the geometric axis of rotation. This minimises centrifugal forces, reducing vibration, <a href=\"https:\/\/vibromera.eu\/glossary\/bearing-fault-frequencies\/\">bearing<\/a> loads, noise, and energy consumption. Correction is done by adding or removing weight at specific locations and angles, guided by vibration measurements and phase analysis. The acceptance criterion is defined by <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a> (ISO 21940-11) <a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\">G-grades<\/a>. The two types are <strong>static (single-plane)<\/strong> for disc-like rotors and <strong>dynamic (two-plane)<\/strong> for elongated rotors.<\/p>\n <\/div>\n\n <p><a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">Unbalance<\/a> is the most common source of vibration in rotating machinery. When mass distribution is imperfect \u2014 due to manufacturing tolerances, material non-homogeneity, corrosion, deposit buildup, or damage \u2014 centrifugal forces are generated that increase with the square of speed. A small unbalance at low speed can become destructive at high speed.<\/p>\n\n <p>Balancing addresses this by iteratively measuring vibration response and adjusting mass distribution until residual <a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">unbalance<\/a> is within tolerance. It is both a manufacturing process (on shop balancing machines) and a maintenance process (field balancing on installed equipment).<\/p>\n\n <h2 id=\"method\">The Influence Coefficient Method<\/h2>\n <p>Modern balancing \u2014 both on dedicated machines and in the field \u2014 uses the <strong>influence coefficient (trial weight) method<\/strong>. The physical principle: if we know how a known mass at a known position changes the vibration, we can calculate the mass and position needed to cancel the original unbalance.<\/p>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Influence Coefficient<\/div>\n <div class=\"formula-main\">\u03b1 = (V<sub>trial<\/sub> \u2212 V<sub>initial<\/sub>) \/ T<\/div>\n <div class=\"formula-note\">\u03b1 = influence coefficient (vibration per unit unbalance) | V = vibration vector (amplitude\u2220phase) | T = trial weight vector (mass\u2220angle)<\/div>\n <\/div>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Correction Calculation<\/div>\n <div class=\"formula-main\">C = \u2212V<sub>initial<\/sub> \/ \u03b1<\/div>\n <div class=\"formula-note\">C = correction weight vector (mass\u2220angle) \u2014 the weight that produces vibration equal and opposite to V<sub>initial<\/sub><\/div>\n <\/div>\n\n <p>For two-plane balancing, the system becomes a 2\u00d72 matrix (four influence coefficients accounting for cross-coupling between planes), but the principle is identical. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> solves this automatically \u2014 the operator just runs the machine and attaches trial weights.<\/p>\n\n <h3>Trial Weight Selection<\/h3>\n <p>The trial weight should produce a noticeable change in vibration (ideally 10\u201330% of the initial level) without creating dangerous loads. A useful starting estimate:<\/p>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Trial Weight Estimate<\/div>\n <div class=\"formula-main\">m<sub>trial<\/sub> \u2248 (10 \u00d7 M) \/ (R \u00d7 (n\/1000)\u00b2)<\/div>\n <div class=\"formula-note\">m in grams | M = rotor mass (kg) | R = trial radius (mm) | n = RPM \u2014 rule of thumb for approximately 10% of G 6.3 unbalance<\/div>\n <\/div>\n\n <h2 id=\"when-to-balance\">When to Balance \u2014 Vibration Signature<\/h2>\n <p>How do you know vibration is caused by unbalance rather than <a href=\"https:\/\/vibromera.eu\/glossary\/misalignment\/\">misalignment<\/a>, looseness, or <a href=\"https:\/\/vibromera.eu\/glossary\/bearing-fault-frequencies\/\">bearing defects<\/a>?<\/p>\n\n <div class=\"info-box\">\n <div class=\"box-title\">Unbalance Vibration Signature<\/div>\n <p><strong>Frequency:<\/strong> Dominant peak at exactly 1\u00d7 RPM (running speed) in the <a href=\"https:\/\/vibromera.eu\/glossary\/fft\/\">FFT<\/a> spectrum.<\/p>\n <p><strong>Direction:<\/strong> Primarily radial (horizontal and vertical). Axial component is small.<\/p>\n <p><strong>Phase:<\/strong> Stable, repeatable phase angle at 1\u00d7. Phase does not drift over time.<\/p>\n <p><strong>Speed dependence:<\/strong> Amplitude increases with the square of speed (proportional to \u03c9\u00b2).<\/p>\n <p><strong>Contrast with misalignment:<\/strong> Misalignment produces significant 2\u00d7 and\/or axial 1\u00d7 components. Bearing defects produce non-synchronous frequencies.<\/p>\n <\/div>\n\n <p>Before balancing, always verify the diagnosis. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> spectrum analyser (F1 mode) shows the full <a href=\"https:\/\/vibromera.eu\/glossary\/fft\/\">FFT<\/a> spectrum, allowing confirmation that 1\u00d7 dominates before proceeding to balance.<\/p>\n\n <h2 id=\"correction\">Correction Methods<\/h2>\n <h3>Adding Mass<\/h3>\n <ul>\n <li><strong>Clip-on weights:<\/strong> Spring-clip zinc or steel weights. Common for fans, wheels. Quick, non-permanent.<\/li>\n <li><strong>Bolt-on weights:<\/strong> Precision weights secured with bolts in tapped holes or T-slots. Standard for large rotors, turbines.<\/li>\n <li><strong>Weld-on weights:<\/strong> Steel plates or rods tack-welded to the rotor. Permanent. Common for heavy industrial fans and crusher rotors.<\/li>\n <li><strong>Epoxy\/putty:<\/strong> Two-part adhesive with metal filler. Good for irregular surfaces. Limited to moderate temperatures.<\/li>\n <li><strong>Set screws:<\/strong> Threaded into radial holes. Common on coupling hubs and spindles. Adjustable.<\/li>\n <\/ul>\n <h3>Removing Mass<\/h3>\n <ul>\n <li><strong>Drilling:<\/strong> Remove material from the heavy spot. Precise control of mass removed (mass = density \u00d7 volume). Irreversible.<\/li>\n <li><strong>Milling\/grinding:<\/strong> Remove material from the rim or face. Common on turbine wheels, brake rotors.<\/li>\n <\/ul>\n\n <h3>Weight Splitting<\/h3>\n <p>When the exact calculated angle falls between accessible positions (e.g., between bolt holes on a coupling), the correction is split between the two adjacent positions using vector decomposition. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> includes an automatic weight-splitting calculator.<\/p>\n\n <h2 id=\"field-balancing\">Field Balancing (In-Situ)<\/h2>\n <p>Field balancing means balancing a rotor <em>without removing it from the machine<\/em>. This eliminates disassembly downtime and accounts for the actual operating conditions (alignment, bearing preload, foundation effects) that shop balancing cannot replicate.<\/p>\n\n <div class=\"info-box success\">\n <div class=\"box-title\">Balanset-1A Field Balancing Kit<\/div>\n <p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> is a complete portable field balancing system: 2-channel vibration analyser, laser tachometer, built-in <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940<\/a> tolerance calculator, single-plane (F2) and two-plane (F3) balancing modes, automatic weight splitting, and formal balance report generation (F6). Measurement accuracy: \u00b15% velocity, \u00b11\u00b0 phase. Suitable for G 16 through G 2.5.<\/p>\n <p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-4\/\">Balanset-4<\/a> extends to 4 channels for complex multi-bearing rotors or simultaneous monitoring of multiple machines.<\/p>\n <\/div>\n\n <h3>Advantages of Field Balancing<\/h3>\n <ul>\n <li><strong>No disassembly:<\/strong> Saves hours or days of downtime for large machines.<\/li>\n <li><strong>Real operating conditions:<\/strong> Includes alignment, bearing preload, thermal state, foundation effects.<\/li>\n <li><strong>Trim balancing:<\/strong> Corrects assembly-introduced unbalance that shop balancing cannot address.<\/li>\n <li><strong>Post-maintenance verification:<\/strong> Quick check after impeller replacement, coupling change, or bearing overhaul.<\/li>\n <\/ul>\n\n <h2 id=\"standards\">Standards and Tolerances<\/h2>\n <p>Balancing is not \"as good as possible\" \u2014 it is \"within tolerance.\" The tolerance is defined by international standards:<\/p>\n\n <div class=\"table-wrap\">\n <div class=\"table-title\">\ud83d\udccf Key Balancing Standards<\/div>\n <div class=\"table-scroll\"><table>\n <thead><tr><th>Standard<\/th><th>Subject<\/th><th>Key Content<\/th><\/tr><\/thead>\n <tbody>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1 \/ ISO 21940-11<\/a><\/td><td>Balance quality grades (G-grades)<\/td><td>G 0.4\u2013G 4000 scale. Formula: U<sub>per<\/sub> = (9 549\u00d7G\u00d7M)\/n. G 6.3 = standard for fans, pumps, motors.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\">ISO 1940-2 \/ ISO 21940-2<\/a><\/td><td>Vocabulary<\/td><td>Definitions: unbalance types, rotor classifications, machine types, quality terms.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a><\/td><td>Industrial fans<\/td><td>BV categories (balance) and FV categories (vibration) specific to fan impellers.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816 \/ ISO 20816<\/a><\/td><td>Machine vibration evaluation<\/td><td>Measures the operational <em>result<\/em> of balance quality. Zone A\/B\/C\/D classification.<\/td><\/tr>\n <tr><td>ISO 21940-12<\/td><td>Flexible rotors<\/td><td>Multi-speed, multi-plane procedures for rotors above first bending critical speed.<\/td><\/tr>\n <tr><td>ISO 21940-14<\/td><td>Balancing procedures<\/td><td>General procedures for balancing in several planes.<\/td><\/tr>\n <tr><td>API 610 \/ API 617<\/td><td>Petroleum pumps \/ compressors<\/td><td>Reference ISO 1940 G-grades for rotor balance requirements.<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <\/div>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">ISO 1940-1 Tolerance Formula<\/div>\n <div class=\"formula-main\">U<sub>per<\/sub> = (9 549 \u00d7 G \u00d7 M) \/ n<\/div>\n <div class=\"formula-note\">U<sub>per<\/sub> = permissible residual unbalance (g\u00b7mm) | G = grade (mm\/s) | M = mass (kg) | n = max RPM<\/div>\n <\/div>\n\n <h2 id=\"cases\">Worked Examples<\/h2>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 1: Centrifugal Fan \u2014 Single-Plane Field Balancing<\/div>\n <p><strong>Machine:<\/strong> 22 kW centrifugal supply fan, 1 460 RPM, impeller mass 38 kg. Excessive vibration: 8.2 mm\/s RMS on drive-end bearing. FFT confirms dominant 1\u00d7 peak with stable phase.<\/p>\n <p><strong>Setup:<\/strong> <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> sensor on DE bearing, laser tachometer on shaft. Mode F2 (single-plane \u2014 L\/D < 0.4).<\/p>\n <p><strong>Step 1:<\/strong> Initial run: 8.2 mm\/s at 47\u00b0.<\/p>\n <p><strong>Step 2:<\/strong> Trial weight: 15 g at 0\u00b0 on fan hub, R = 200 mm.<\/p>\n <p><strong>Step 3:<\/strong> Trial run: 5.9 mm\/s at 112\u00b0.<\/p>\n <p><strong>Step 4:<\/strong> Software calculates: correction = <strong>22 g at 198\u00b0<\/strong>, R = 200 mm.<\/p>\n <p><strong>Step 5:<\/strong> Install weld-on weight 22 g at 198\u00b0. Remove trial weight.<\/p>\n <p><strong>Step 6:<\/strong> Verification: <strong>0.9 mm\/s<\/strong>. ISO tolerance G 6.3 \u2192 U<sub>per<\/sub> = 1 570 g\u00b7mm. Achieved: ~180 g\u00b7mm. \u2705 Pass.<\/p>\n <\/div>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 2: Motor-Pump Assembly \u2014 Two-Plane<\/div>\n <p><strong>Machine:<\/strong> 45 kW motor + centrifugal pump, 2 950 RPM, rotor mass 55 kg. Vibration: DE bearing 6.1 mm\/s, NDE bearing 4.8 mm\/s. Phase difference ~140\u00b0 \u2192 dynamic unbalance.<\/p>\n <p><strong>Setup:<\/strong> Balanset-1A two sensors (DE + NDE), mode F3. Correction planes: coupling hub (plane 1) and motor fan end (plane 2).<\/p>\n <p><strong>Runs:<\/strong> Initial \u2192 trial plane 1 (10 g at 0\u00b0) \u2192 trial plane 2 (8 g at 0\u00b0).<\/p>\n <p><strong>Result:<\/strong> Software solves 2\u00d72 matrix. Correction: plane 1 = <strong>18 g at 245\u00b0<\/strong>, plane 2 = <strong>12 g at 68\u00b0<\/strong>.<\/p>\n <p><strong>Verification:<\/strong> DE: <strong>0.7 mm\/s<\/strong>, NDE: <strong>0.5 mm\/s<\/strong>. G 6.3 limit: 1 122 g\u00b7mm. \u2705 Both planes well within tolerance.<\/p>\n <\/div>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 3: Crusher Rotor \u2014 Coarse G 16<\/div>\n <p><strong>Machine:<\/strong> Hammer mill crusher, 980 RPM, rotor mass 420 kg. After hammer replacement, vibration increased to 14.5 mm\/s.<\/p>\n <p><strong>Specification:<\/strong> G 16 (heavy-duty, severe conditions). U<sub>per<\/sub> = 9 549 \u00d7 16 \u00d7 420 \/ 980 = <strong>65 500 g\u00b7mm<\/strong>.<\/p>\n <p><strong>Procedure:<\/strong> Single-plane (disc-like rotor). Trial 150 g at 0\u00b0 on rim. Correction: <strong>280 g at 315\u00b0<\/strong>. Weld-on steel plate.<\/p>\n <p><strong>Result:<\/strong> <strong>2.8 mm\/s<\/strong>. Residual ~5 600 g\u00b7mm. \u2705 Well within G 16 limit.<\/p>\n <\/div>\n\n <h2 id=\"related-standards\">Related Topics<\/h2>\n <ul>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a>:<\/strong> G-grade tolerance system \u2014 the acceptance criterion for balancing results.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\">ISO 1940-2<\/a>:<\/strong> Vocabulary \u2014 definitions of all balancing terms.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\">Balance Quality Grade<\/a>:<\/strong> Interactive G-grade calculator.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">Unbalance<\/a>:<\/strong> The physical condition that balancing corrects.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a>:<\/strong> Fan-specific BV\/FV categories.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/harmonics-vibration\/\">Harmonics<\/a>:<\/strong> Distinguishing 1\u00d7 (unbalance) from 2\u00d7 (misalignment) and other orders.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/natural-frequency\/\">Natural Frequency<\/a>:<\/strong> Rigid\/flexible rotor boundary \u2014 critical for balancing approach.<\/li>\n <\/ul>\n\n <hr style=\"margin:48px 0 24px;border:none;border-top:1px solid var(--border-light);\">\n <p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary Index<\/a><\/p>\n <\/article>\n\n <aside class=\"toc-sidebar\">\n <div class=\"toc-box\">\n <h3>On This Page<\/h3>\n <a href=\"#types\">Static vs. Dynamic<\/a>\n <a class=\"sub\" href=\"#types\">Comparison table<\/a>\n <a href=\"#procedure\">Procedure Steps (6)<\/a>\n <a href=\"#benefits\">Benefits (5)<\/a>\n <a href=\"#definition\">What is Rotor Balancing?<\/a>\n <a href=\"#method\">Influence Coefficient Method<\/a>\n <a class=\"sub\" href=\"#method\">Trial weight selection<\/a>\n <a href=\"#when-to-balance\">When to Balance<\/a>\n <a class=\"sub\" href=\"#when-to-balance\">1\u00d7 vibration signature<\/a>\n <a href=\"#correction\">Correction Methods<\/a>\n <a class=\"sub\" href=\"#correction\">Adding \/ removing mass<\/a>\n <a class=\"sub\" href=\"#correction\">Weight splitting<\/a>\n <a href=\"#field-balancing\">Field Balancing<\/a>\n <a href=\"#standards\">Standards & Tolerances<\/a>\n <a href=\"#cases\">Case Studies (3)<\/a>\n <a href=\"#faq\">FAQ (8 Questions)<\/a>\n <\/div>\n <div class=\"toc-box\" style=\"margin-top:24px;background:var(--navy);border-color:var(--navy);\">\n <h3 style=\"color:#fff;\">Balancing Equipment<\/h3>\n <p style=\"color:rgba(255,255,255,.6);font-size:13px;margin-bottom:12px;\">Complete portable field balancing: 1-plane and 2-plane modes, ISO 1940 tolerance calculator, spectrum analyser, automatic weight splitting, balance reports.<\/p>\n <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" style=\"display:block;padding:8px 14px;background:var(--blue);color:white;border-radius:6px;text-align:center;font-weight:600;font-size:14px;text-decoration:none;margin-bottom:8px;border-left:none;\">Balanset-1A \u2192<\/a>\n <a href=\"https:\/\/vibromera.eu\/product\/balanset-4\/\" style=\"display:block;padding:8px 14px;background:rgba(255,255,255,.1);color:white;border-radius:6px;text-align:center;font-weight:600;font-size:14px;text-decoration:none;border:1px solid rgba(255,255,255,.2);border-left:none;\">Balanset-4 \u2192<\/a>\n <\/div>\n <\/aside>\n <\/div>\n <\/div>\n<\/main>\n\n\n<section class=\"section-bg alt\" id=\"faq\">\n <div class=\"container\" style=\"max-width:1000px;\">\n <div class=\"section-header\"><h2>Frequently Asked Questions \u2014 Rotor Balancing<\/h2><p>Procedures, types, diagnosis, and standards<\/p><\/div>\n <div style=\"display:flex;flex-direction:column;gap:16px;\">\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What is rotor balancing?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">The process of improving mass distribution of a rotating body so that its centre of mass coincides with the geometric rotation axis. Minimises centrifugal forces \u2192 reduces vibration, bearing loads, noise, energy loss. Correction: adding\/removing weight at specific locations\/angles. Acceptance: <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a> G-grades.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Static vs. dynamic balancing?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Static (1-plane):<\/strong> corrects displaced CoM \u2014 single heavy spot \u2014 disc-like rotors (L\/D < 0.5). <strong>Dynamic (2-plane):<\/strong> corrects both force + couple \u2014 general case \u2014 elongated rotors. Most real machines need dynamic. When in doubt, use 2-plane.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> How does the trial weight method work?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Measure initial vibration \u2192 attach known trial weight \u2192 measure again \u2192 vector difference = effect of trial. Software calculates influence coefficient, then determines the exact correction mass and angle to cancel the original unbalance. Remove trial, install correction, verify. <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> automates the calculation.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Single-plane or two-plane?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Single-plane: fan impellers, pulleys, grinding wheels, flywheels (L\/D < 0.5). Two-plane: motors, shafts, pumps, rolls, turbines (L\/D > 0.5). Balanset-1A: F2 = single, F3 = two-plane. If bearings vibrate out of phase at 1\u00d7, couple unbalance is present \u2192 two-plane needed.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What ISO standard for tolerances?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 21940-11 (ISO 1940-1)<\/a>: G-grade system. G 6.3 = standard for fans\/pumps\/motors. G 2.5 = turbines\/compressors. U<sub>per<\/sub> = (9 549 \u00d7 G \u00d7 M) \/ n. <a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a> extends to fan-specific BV categories. <a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816<\/a> evaluates vibration in operation.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Can I balance in-situ (without removing the rotor)?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Yes \u2014 field balancing. A portable <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> uses vibration sensors + tachometer on the installed machine. Trial-weight method determines correction without a dedicated balancing machine. Saves hours of disassembly. Accounts for actual operating conditions (alignment, temperature, foundation).<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What are common correction methods?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Adding:<\/strong> clip-on, bolt-on, weld-on weights; epoxy\/putty; set screws. <strong>Removing:<\/strong> drilling, milling, grinding. Choice depends on rotor design, temperature, permanence needs. Weight splitting distributes correction between adjacent accessible positions when the exact angle is blocked.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> How do I know it's unbalance and not misalignment?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Unbalance:<\/strong> dominant 1\u00d7 peak, radial, stable phase, amplitude \u221d speed\u00b2. <strong><a href=\"https:\/\/vibromera.eu\/glossary\/misalignment\/\">Misalignment<\/a>:<\/strong> significant 2\u00d7 and\/or axial 1\u00d7, phase relationship between bearings, amplitude less speed-dependent. Use Balanset-1A spectrum analyser (F1) to confirm before balancing.<\/div><\/details>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section style=\"padding:32px 0;background:var(--white);border-top:1px solid var(--border-light);\">\n <div class=\"container\" style=\"max-width:1000px;\">\n <h3 style=\"font-family:'DM Serif Display',serif;font-size:22px;color:var(--navy);margin-bottom:20px;\">Related Glossary Articles<\/h3>\n <div style=\"display:grid;grid-template-columns:repeat(3,1fr);gap:16px;\">\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 1940-1<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">G-grade tolerance system \u2014 the acceptance criterion<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Balance Quality Grade<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Interactive G-grade calculator with tolerance tables<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Unbalance<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">The physical condition that balancing corrects<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 14694<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Fan-specific balance & vibration categories<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 1940-2<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Vocabulary \u2014 definitions of all balancing terms<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/natural-frequency\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Natural Frequency<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Critical speeds \u2014 rigid vs. flexible rotor boundary<\/div><\/a>\n <\/div>\n <\/div>\n<\/section>\n\n<section class=\"shop-cta\">\n <div class=\"container\">\n <h2>Balance Any Rotor \u2014 In the Field<\/h2>\n <p>Single-plane and two-plane modes, ISO 1940 tolerance calculator, spectrum analyser for diagnosis, automatic weight splitting, and formal balance reports \u2014 all in one portable instrument.<\/p>\n <a href=\"https:\/\/vibromera.eu\/shop\/\" class=\"cta-btn\">Browse Balancing Equipment \u2192<\/a>\n <\/div>\n<\/section>\n\n<footer class=\"page-footer\">\n <div class=\"container\"><p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary<\/a> | <a href=\"https:\/\/vibromera.eu\/\">vibromera.eu<\/a><\/p><\/div>\n<\/footer>\n\n<\/body>\n<\/html><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Um guia completo sobre balanceamento de rotores. Aprenda sobre balanceamento est\u00e1tico vs. din\u00e2mico, procedimentos de plano \u00fanico e duplo e a import\u00e2ncia de normas como a ISO 21940.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[109,112],"tags":[],"class_list":["post-20632","glossary","type-glossary","status-publish","hentry","category-glossary","category-iso-standards"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":4,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632\/revisions"}],"predecessor-version":[{"id":101501,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632\/revisions\/101501"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/media?parent=20632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/categories?post=20632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/tags?post=20632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

\n\n\n\n\nRotor Balancing \u2014 Procedures, Types & Standards \u2014 Vibromera<\/title>\n<meta name=\"description\" content=\"Complete guide to rotor balancing: static vs. dynamic (single-plane and two-plane), the influence coefficient method, step-by-step field procedure, ISO 21940 \/ ISO 1940-1 tolerances, correction techniques, and worked examples with the Balanset-1A.\">\n<meta name=\"keywords\" content=\"rotor balancing, dynamic balancing, static balancing, single-plane balancing, two-plane balancing, influence coefficient method, trial weight, correction weight, field balancing, in-situ balancing, vibration reduction, ISO 21940, G-grade, unbalance correction, Balanset\">\n<meta name=\"author\" content=\"Vibromera\">\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large\">\n\n\n\n\n\n\n\n<meta property=\"og:type\" content=\"article\">\n<meta property=\"og:title\" content=\"Rotor Balancing \u2014 Procedures, Types & Standards (Complete Guide)\">\n<meta property=\"og:description\" content=\"Static vs. dynamic balancing, step-by-step influence coefficient method, ISO 21940 tolerances, correction techniques, and field balancing with Balanset-1A.\">\n<meta property=\"og:url\" content=\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/\">\n<meta property=\"og:site_name\" content=\"Vibromera \u2014 Vibration Analysis & Balancing Equipment\">\n<meta property=\"og:locale\" content=\"en_US\">\n<meta property=\"og:image\" content=\"https:\/\/vibromera.eu\/wp-content\/uploads\/rotor-balancing-og.jpg\">\n<meta property=\"article:publisher\" content=\"https:\/\/vibromera.eu\/\">\n<meta property=\"article:section\" content=\"Glossary\">\n<meta property=\"article:tag\" content=\"Rotor Balancing\">\n<meta property=\"article:tag\" content=\"Dynamic Balancing\">\n<meta property=\"article:tag\" content=\"Field Balancing\">\n<meta name=\"twitter:card\" content=\"summary_large_image\">\n<meta name=\"twitter:title\" content=\"Rotor Balancing \u2014 Static vs. Dynamic, Procedures & ISO Tolerances\">\n<meta name=\"twitter:description\" content=\"Step-by-step balancing guide: influence coefficient method, single-plane and two-plane procedures, ISO 21940 G-grade tolerances.\">\n<meta name=\"geo.region\" content=\"EU\">\n<meta name=\"geo.placename\" content=\"Porto, Portugal\">\n<meta name=\"geo.position\" content=\"41.1579;-8.6291\">\n<meta name=\"ICBM\" content=\"41.1579, -8.6291\">\n<script type=\"application\/ld+json\">\n{\n \"@context\":\"https:\/\/schema.org\",\n \"@graph\":[\n {\n \"@type\":\"TechArticle\",\n \"@id\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/#article\",\n \"headline\":\"Rotor Balancing: Procedures, Types & Standards \u2014 Complete Guide\",\n \"description\":\"Comprehensive guide to rotor balancing: static vs. dynamic, single-plane and two-plane procedures, the influence coefficient method, ISO 21940\/1940-1 tolerances, field balancing techniques, and practical worked examples.\",\n \"author\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\n \"publisher\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\",\"logo\":{\"@type\":\"ImageObject\",\"url\":\"https:\/\/vibromera.eu\/wp-content\/uploads\/vibromera-logo.png\"}},\n \"mainEntityOfPage\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/\",\n \"datePublished\":\"2024-02-20\",\n \"dateModified\":\"2026-02-07\",\n \"inLanguage\":\"en\",\n \"about\":[\n {\"@type\":\"Thing\",\"name\":\"Rotor Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Dynamic Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Field Balancing\"},\n {\"@type\":\"Thing\",\"name\":\"Vibration Reduction\"}\n ]\n },\n {\n \"@type\":\"FAQPage\",\n \"@id\":\"https:\/\/vibromera.eu\/glossary\/rotor-balancing\/#faq\",\n \"mainEntity\":[\n {\"@type\":\"Question\",\"name\":\"What is rotor balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Rotor balancing is the process of improving the mass distribution of a rotating body so that its centre of mass coincides with its geometric axis of rotation. This minimises centrifugal forces, reducing vibration, bearing loads, noise, and energy consumption. Correction is done by adding or removing weight at specific locations and angles, guided by vibration measurements and phase analysis.\"}},\n {\"@type\":\"Question\",\"name\":\"What is the difference between static and dynamic balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Static (single-plane) balancing corrects a single heavy spot \u2014 the centre of mass is displaced from the axis but the inertia axis stays parallel. Suitable for narrow disc-like rotors (L\/D < 0.5). Dynamic (two-plane) balancing corrects both force and couple unbalance \u2014 the general case where the inertia axis is skewed. Required for elongated rotors. Most real rotors need dynamic balancing.\"}},\n {\"@type\":\"Question\",\"name\":\"How does the trial weight (influence coefficient) method work?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Step 1: Measure initial vibration (amplitude + phase). Step 2: Attach a known trial weight at a known angle. Step 3: Measure new vibration. Step 4: The vector difference between runs reveals how that location influences vibration \u2014 the influence coefficient. Step 5: Software calculates the exact correction mass and angle to cancel the original unbalance. Step 6: Remove trial weight, install correction, verify.\"}},\n {\"@type\":\"Question\",\"name\":\"When should I use single-plane vs. two-plane balancing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Single-plane: rotors with L\/D < 0.5 (narrow, disc-like) \u2014 fan impellers, pulleys, narrow grinding wheels, flywheels. Two-plane: rotors with L\/D > 0.5 (elongated) \u2014 motor armatures, multi-stage pump shafts, paper rolls, cardan shafts. When in doubt, use two-plane \u2014 it handles both static and couple unbalance.\"}},\n {\"@type\":\"Question\",\"name\":\"What ISO standard applies to rotor balancing tolerances?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 21940-11 (formerly ISO 1940-1) defines the G-grade balance quality system. G 6.3 is the standard for most industrial fans, pumps, and motors. G 2.5 for turbines and critical machinery. The formula U_per = (9549 \u00d7 G \u00d7 M) \/ n gives permissible residual unbalance in g\u00b7mm. ISO 14694 extends this to fan-specific BV categories.\"}},\n {\"@type\":\"Question\",\"name\":\"Can I balance a rotor without removing it from the machine?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes \u2014 this is called field balancing or in-situ balancing. A portable balancer like the Balanset-1A uses vibration sensors and a tachometer mounted on the installed machine. The trial-weight influence coefficient method determines correction without needing a dedicated balancing machine. This saves hours of disassembly\/reassembly downtime.\"}},\n {\"@type\":\"Question\",\"name\":\"What are common correction methods?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Adding mass: clip-on weights, bolt-on weights, weld-on weights, epoxy\/putty, set screws. Removing mass: drilling, milling, grinding. The choice depends on rotor design, operating environment, and whether the correction is permanent or for trim balancing. Weight splitting distributes correction between adjacent accessible positions when the exact angle is not reachable.\"}},\n {\"@type\":\"Question\",\"name\":\"How do I know if vibration is caused by unbalance?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Unbalance produces vibration at exactly 1\u00d7 RPM (the running speed) in the radial direction. In an FFT spectrum, a dominant 1\u00d7 peak with stable phase angle is the classic signature. If vibration is at 2\u00d7, 3\u00d7, or other multiples, other faults (misalignment, looseness, bearing defects) are more likely. 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h2{font-size:24px}}\n@media(max-width:480px){.hero h1{font-size:24px}.quick-nav a{padding:12px 12px;font-size:13px}.benefits-grid{grid-template-columns:1fr}}\n@media print{.quick-nav,.shop-cta,.toc-sidebar{display:none}}\n<\/style>\n<\/head>\n<body>\n\n<header class=\"hero\">\n <div class=\"hero-inner\">\n <div class=\"breadcrumb\"><a href=\"https:\/\/vibromera.eu\/\">Home<\/a> \u2192 <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary<\/a> \u2192 Rotor Balancing<\/div>\n <h1>Rotor Balancing \u2014 <span>Procedures, Types<\/span> & Standards<\/h1>\n <div class=\"canon-badge\"><span style=\"font-size:14px;\">\ud83d\udccc<\/span> Canonical Reference Article \u2014 vibromera.eu<\/div>\n <p class=\"subtitle\">The complete guide to balancing rotating machinery: static vs. dynamic (single-plane and two-plane), the influence coefficient method, ISO 21940 tolerances, field balancing, and correction techniques.<\/p>\n <\/div>\n<\/header>\n\n<nav class=\"quick-nav\">\n <div class=\"quick-nav-inner\">\n <a href=\"#types\">\u2696 Static vs. Dynamic<\/a>\n <a href=\"#procedure\">\ud83d\udd27 Procedure Steps<\/a>\n <a href=\"#benefits\">\ud83d\udcc8 Benefits<\/a>\n <a href=\"#definition\">\ud83d\udcd0 Overview<\/a>\n <a href=\"#method\">\u2699 Method<\/a>\n <a href=\"#when-to-balance\">\ud83c\udfaf When to Balance<\/a>\n <a href=\"#correction\">\ud83d\udd29 Correction<\/a>\n <a href=\"#field-balancing\">\ud83c\udfed Field Balancing<\/a>\n <a href=\"#standards\">\ud83d\udccf Standards<\/a>\n <a href=\"#cases\">\ud83d\udcdd Cases<\/a>\n <a href=\"#faq\">\u2753 FAQ<\/a>\n <\/div>\n<\/nav>\n\n\n<section class=\"section-bg\" id=\"types\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>Static vs. Dynamic Balancing<\/h2>\n <p>The two fundamental balancing types \u2014 determined by rotor geometry and the type of unbalance present<\/p>\n <\/div>\n <div class=\"type-grid\">\n <div class=\"type-card static\">\n <div class=\"tc-icon\">\ud83d\udccd<\/div>\n <div class=\"tc-title\">Static (Single-Plane)<\/div>\n <div class=\"tc-subtitle s\">One correction plane<\/div>\n <div class=\"tc-body\">Corrects <strong>static unbalance<\/strong> \u2014 the rotor's centre of mass is displaced from the rotation axis but the inertia axis remains parallel. Equivalent to a single \"heavy spot.\" Detectable without rotation (gravity reveals it on knife-edges).<\/div>\n <div class=\"tc-specs\">\n <div class=\"tc-spec\"><span class=\"spec-label\">Planes<\/span><span class=\"spec-value\">1 correction plane<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Sensors<\/span><span class=\"spec-value\">1 vibration sensor + 1 tachometer<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Rotor shape<\/span><span class=\"spec-value\">Disc-like, L\/D < 0.5<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Examples<\/span><span class=\"spec-value\">Fan impellers, pulleys, grinding wheels, narrow flywheels<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Balanset mode<\/span><span class=\"spec-value\">F2 \u2014 Single-Plane<\/span><\/div>\n <\/div>\n <\/div>\n <div class=\"type-card dynamic\">\n <div class=\"tc-icon\">\ud83d\udcab<\/div>\n <div class=\"tc-title\">Dynamic (Two-Plane)<\/div>\n <div class=\"tc-subtitle d\">Two correction planes<\/div>\n <div class=\"tc-body\">Corrects <strong>dynamic unbalance<\/strong> \u2014 the general case combining static and couple components. The inertia axis is neither parallel to nor intersecting the rotation axis. Only detectable while spinning. Creates both force and rocking-moment vibration.<\/div>\n <div class=\"tc-specs\">\n <div class=\"tc-spec\"><span class=\"spec-label\">Planes<\/span><span class=\"spec-value\">2 correction planes<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Sensors<\/span><span class=\"spec-value\">2 vibration sensors + 1 tachometer<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Rotor shape<\/span><span class=\"spec-value\">Elongated, L\/D > 0.5<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Examples<\/span><span class=\"spec-value\">Motor armatures, pump shafts, paper rolls, cardan shafts<\/span><\/div>\n <div class=\"tc-spec\"><span class=\"spec-label\">Balanset mode<\/span><span class=\"spec-value\">F3 \u2014 Two-Plane<\/span><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"table-wrap\">\n <div class=\"table-title\">\ud83d\udcca Single-Plane vs. Two-Plane \u2014 Decision Guide<\/div>\n <div class=\"table-scroll\"><table>\n <thead><tr><th>Criterion<\/th><th><span class=\"tag sp\">Single-Plane<\/span><\/th><th><span class=\"tag tp\">Two-Plane<\/span><\/th><\/tr><\/thead>\n <tbody>\n <tr><td>Unbalance type corrected<\/td><td>Static only<\/td><td>Static + couple (dynamic)<\/td><\/tr>\n <tr><td>Rotor geometry<\/td><td>L\/D < 0.5 (disc-like)<\/td><td>L\/D > 0.5 (elongated)<\/td><\/tr>\n <tr><td>Number of runs<\/td><td>2 (initial + trial)<\/td><td>3\u20134 (initial + 2 trials, or cross-coupling)<\/td><\/tr>\n <tr><td>Sensors required<\/td><td>1 accelerometer + tacho<\/td><td>2 accelerometers + tacho<\/td><\/tr>\n <tr><td>Bearing vibration pattern<\/td><td>In-phase at 1\u00d7<\/td><td>Phase varies (not in-phase, not 180\u00b0)<\/td><\/tr>\n <tr><td>Typical rotors<\/td><td>Fan impellers, pulleys, grinding wheels<\/td><td>Motors, pumps, rolls, turbines, shafts<\/td><\/tr>\n <tr><td>ISO plane recommendation<\/td><td>Narrow rotors per ISO 1940-1 \u00a74.3<\/td><td>Standard for all elongated rotors<\/td><\/tr>\n <tr><td>Balanset-1A mode<\/td><td class=\"mono\">F2<\/td><td class=\"mono\">F3<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section class=\"section-bg alt\" id=\"procedure\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>The Balancing Procedure<\/h2>\n <p>Influence coefficient (trial weight) method \u2014 the standard approach for field and shop balancing<\/p>\n <\/div>\n <div class=\"steps-grid\">\n <div class=\"step-card\"><div class=\"step-num\">1<\/div><div class=\"step-icon\">\ud83d\udcca<\/div><div class=\"step-title\">Initial Measurement<\/div><div class=\"step-desc\">Run the machine at operating speed. Measure vibration amplitude (mm\/s) and phase angle (\u00b0) at each bearing. This is the <strong>baseline<\/strong> \u2014 the unbalance signature. Record in Balanset-1A.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">2<\/div><div class=\"step-icon\">\u2696\ufe0f<\/div><div class=\"step-title\">Attach Trial Weight<\/div><div class=\"step-desc\">Stop the machine. Attach a known trial weight at a known angular position in the correction plane. Mass should produce a noticeable but not dangerous vibration change (10\u201330% of initial).<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">3<\/div><div class=\"step-icon\">\ud83d\udcc8<\/div><div class=\"step-title\">Trial Run<\/div><div class=\"step-desc\">Run again at the same speed. Measure new vibration amplitude and phase. The <strong>vector difference<\/strong> between initial and trial runs is caused solely by the trial weight.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">4<\/div><div class=\"step-icon\">\ud83e\uddee<\/div><div class=\"step-title\">Calculate Correction<\/div><div class=\"step-desc\">Software computes the <strong>influence coefficient<\/strong> \u2014 how much vibration change per unit mass at that location. Then calculates exact correction mass (g) and angle (\u00b0) to cancel the original unbalance.<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">5<\/div><div class=\"step-icon\">\ud83d\udd29<\/div><div class=\"step-title\">Install Correction<\/div><div class=\"step-desc\">Remove trial weight. Attach the calculated permanent correction weight at the prescribed angle. For two-plane: repeat steps 2\u20134 for the second plane (Balanset-1A solves both simultaneously).<\/div><\/div>\n <div class=\"step-card\"><div class=\"step-num\">6<\/div><div class=\"step-icon\">\u2705<\/div><div class=\"step-title\">Verify<\/div><div class=\"step-desc\">Final run to confirm residual vibration is within tolerance. Compare measured residual against ISO 1940-1 U<sub>per<\/sub> limit. Balanset-1A displays pass\/fail and generates a balance report.<\/div><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section class=\"section-bg\" id=\"benefits\">\n <div class=\"container\">\n <div class=\"section-header\">\n <h2>Why Balance? \u2014 The Benefits<\/h2>\n <p>Unbalance is the #1 source of vibration in rotating machinery. Correction delivers measurable returns.<\/p>\n <\/div>\n <div class=\"benefits-grid\">\n <div class=\"benefit-card\"><div class=\"ben-icon\">\u2699\ufe0f<\/div><div class=\"ben-title\">Bearing Life<\/div><div class=\"ben-desc\">Unbalance forces go directly to bearings. 50% vibration reduction \u2192 up to 8\u00d7 bearing life extension.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\udee1\ufe0f<\/div><div class=\"ben-title\">Reliability<\/div><div class=\"ben-desc\">Lower vibration \u2192 less fatigue on seals, shafts, couplings, and foundations. Fewer breakdowns.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\udd07<\/div><div class=\"ben-title\">Noise<\/div><div class=\"ben-desc\">Vibration is the primary noise source. Balanced machines run significantly quieter.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\u26a1<\/div><div class=\"ben-title\">Energy<\/div><div class=\"ben-desc\">Energy wasted on vibration and heat is recovered as useful work. Measurable efficiency gain.<\/div><\/div>\n <div class=\"benefit-card\"><div class=\"ben-icon\">\ud83d\uded1<\/div><div class=\"ben-title\">Safety<\/div><div class=\"ben-desc\">Severe unbalance can cause catastrophic failure. Balancing prevents vibration-induced accidents.<\/div><\/div>\n <\/div>\n <\/div>\n<\/section>\n\n\n<main class=\"main-content\" id=\"definition\">\n <div class=\"container\">\n <div class=\"content-layout\">\n <article class=\"article-content\">\n\n <h2>What is Rotor Balancing?<\/h2>\n <div class=\"info-box\" style=\"border-left-color:var(--navy);background:var(--beige-light);\">\n <div class=\"box-title\" style=\"font-size:16px;\">Quick Answer<\/div>\n <p style=\"font-size:15px;\"><strong>Rotor balancing<\/strong> is the process of improving the mass distribution of a rotating body so that its centre of mass coincides with the geometric axis of rotation. This minimises centrifugal forces, reducing vibration, <a href=\"https:\/\/vibromera.eu\/glossary\/bearing-fault-frequencies\/\">bearing<\/a> loads, noise, and energy consumption. Correction is done by adding or removing weight at specific locations and angles, guided by vibration measurements and phase analysis. The acceptance criterion is defined by <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a> (ISO 21940-11) <a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\">G-grades<\/a>. The two types are <strong>static (single-plane)<\/strong> for disc-like rotors and <strong>dynamic (two-plane)<\/strong> for elongated rotors.<\/p>\n <\/div>\n\n <p><a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">Unbalance<\/a> is the most common source of vibration in rotating machinery. When mass distribution is imperfect \u2014 due to manufacturing tolerances, material non-homogeneity, corrosion, deposit buildup, or damage \u2014 centrifugal forces are generated that increase with the square of speed. A small unbalance at low speed can become destructive at high speed.<\/p>\n\n <p>Balancing addresses this by iteratively measuring vibration response and adjusting mass distribution until residual <a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">unbalance<\/a> is within tolerance. It is both a manufacturing process (on shop balancing machines) and a maintenance process (field balancing on installed equipment).<\/p>\n\n <h2 id=\"method\">The Influence Coefficient Method<\/h2>\n <p>Modern balancing \u2014 both on dedicated machines and in the field \u2014 uses the <strong>influence coefficient (trial weight) method<\/strong>. The physical principle: if we know how a known mass at a known position changes the vibration, we can calculate the mass and position needed to cancel the original unbalance.<\/p>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Influence Coefficient<\/div>\n <div class=\"formula-main\">\u03b1 = (V<sub>trial<\/sub> \u2212 V<sub>initial<\/sub>) \/ T<\/div>\n <div class=\"formula-note\">\u03b1 = influence coefficient (vibration per unit unbalance) | V = vibration vector (amplitude\u2220phase) | T = trial weight vector (mass\u2220angle)<\/div>\n <\/div>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Correction Calculation<\/div>\n <div class=\"formula-main\">C = \u2212V<sub>initial<\/sub> \/ \u03b1<\/div>\n <div class=\"formula-note\">C = correction weight vector (mass\u2220angle) \u2014 the weight that produces vibration equal and opposite to V<sub>initial<\/sub><\/div>\n <\/div>\n\n <p>For two-plane balancing, the system becomes a 2\u00d72 matrix (four influence coefficients accounting for cross-coupling between planes), but the principle is identical. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> solves this automatically \u2014 the operator just runs the machine and attaches trial weights.<\/p>\n\n <h3>Trial Weight Selection<\/h3>\n <p>The trial weight should produce a noticeable change in vibration (ideally 10\u201330% of the initial level) without creating dangerous loads. A useful starting estimate:<\/p>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">Trial Weight Estimate<\/div>\n <div class=\"formula-main\">m<sub>trial<\/sub> \u2248 (10 \u00d7 M) \/ (R \u00d7 (n\/1000)\u00b2)<\/div>\n <div class=\"formula-note\">m in grams | M = rotor mass (kg) | R = trial radius (mm) | n = RPM \u2014 rule of thumb for approximately 10% of G 6.3 unbalance<\/div>\n <\/div>\n\n <h2 id=\"when-to-balance\">When to Balance \u2014 Vibration Signature<\/h2>\n <p>How do you know vibration is caused by unbalance rather than <a href=\"https:\/\/vibromera.eu\/glossary\/misalignment\/\">misalignment<\/a>, looseness, or <a href=\"https:\/\/vibromera.eu\/glossary\/bearing-fault-frequencies\/\">bearing defects<\/a>?<\/p>\n\n <div class=\"info-box\">\n <div class=\"box-title\">Unbalance Vibration Signature<\/div>\n <p><strong>Frequency:<\/strong> Dominant peak at exactly 1\u00d7 RPM (running speed) in the <a href=\"https:\/\/vibromera.eu\/glossary\/fft\/\">FFT<\/a> spectrum.<\/p>\n <p><strong>Direction:<\/strong> Primarily radial (horizontal and vertical). Axial component is small.<\/p>\n <p><strong>Phase:<\/strong> Stable, repeatable phase angle at 1\u00d7. Phase does not drift over time.<\/p>\n <p><strong>Speed dependence:<\/strong> Amplitude increases with the square of speed (proportional to \u03c9\u00b2).<\/p>\n <p><strong>Contrast with misalignment:<\/strong> Misalignment produces significant 2\u00d7 and\/or axial 1\u00d7 components. Bearing defects produce non-synchronous frequencies.<\/p>\n <\/div>\n\n <p>Before balancing, always verify the diagnosis. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> spectrum analyser (F1 mode) shows the full <a href=\"https:\/\/vibromera.eu\/glossary\/fft\/\">FFT<\/a> spectrum, allowing confirmation that 1\u00d7 dominates before proceeding to balance.<\/p>\n\n <h2 id=\"correction\">Correction Methods<\/h2>\n <h3>Adding Mass<\/h3>\n <ul>\n <li><strong>Clip-on weights:<\/strong> Spring-clip zinc or steel weights. Common for fans, wheels. Quick, non-permanent.<\/li>\n <li><strong>Bolt-on weights:<\/strong> Precision weights secured with bolts in tapped holes or T-slots. Standard for large rotors, turbines.<\/li>\n <li><strong>Weld-on weights:<\/strong> Steel plates or rods tack-welded to the rotor. Permanent. Common for heavy industrial fans and crusher rotors.<\/li>\n <li><strong>Epoxy\/putty:<\/strong> Two-part adhesive with metal filler. Good for irregular surfaces. Limited to moderate temperatures.<\/li>\n <li><strong>Set screws:<\/strong> Threaded into radial holes. Common on coupling hubs and spindles. Adjustable.<\/li>\n <\/ul>\n <h3>Removing Mass<\/h3>\n <ul>\n <li><strong>Drilling:<\/strong> Remove material from the heavy spot. Precise control of mass removed (mass = density \u00d7 volume). Irreversible.<\/li>\n <li><strong>Milling\/grinding:<\/strong> Remove material from the rim or face. Common on turbine wheels, brake rotors.<\/li>\n <\/ul>\n\n <h3>Weight Splitting<\/h3>\n <p>When the exact calculated angle falls between accessible positions (e.g., between bolt holes on a coupling), the correction is split between the two adjacent positions using vector decomposition. The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> includes an automatic weight-splitting calculator.<\/p>\n\n <h2 id=\"field-balancing\">Field Balancing (In-Situ)<\/h2>\n <p>Field balancing means balancing a rotor <em>without removing it from the machine<\/em>. This eliminates disassembly downtime and accounts for the actual operating conditions (alignment, bearing preload, foundation effects) that shop balancing cannot replicate.<\/p>\n\n <div class=\"info-box success\">\n <div class=\"box-title\">Balanset-1A Field Balancing Kit<\/div>\n <p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> is a complete portable field balancing system: 2-channel vibration analyser, laser tachometer, built-in <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940<\/a> tolerance calculator, single-plane (F2) and two-plane (F3) balancing modes, automatic weight splitting, and formal balance report generation (F6). Measurement accuracy: \u00b15% velocity, \u00b11\u00b0 phase. Suitable for G 16 through G 2.5.<\/p>\n <p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-4\/\">Balanset-4<\/a> extends to 4 channels for complex multi-bearing rotors or simultaneous monitoring of multiple machines.<\/p>\n <\/div>\n\n <h3>Advantages of Field Balancing<\/h3>\n <ul>\n <li><strong>No disassembly:<\/strong> Saves hours or days of downtime for large machines.<\/li>\n <li><strong>Real operating conditions:<\/strong> Includes alignment, bearing preload, thermal state, foundation effects.<\/li>\n <li><strong>Trim balancing:<\/strong> Corrects assembly-introduced unbalance that shop balancing cannot address.<\/li>\n <li><strong>Post-maintenance verification:<\/strong> Quick check after impeller replacement, coupling change, or bearing overhaul.<\/li>\n <\/ul>\n\n <h2 id=\"standards\">Standards and Tolerances<\/h2>\n <p>Balancing is not \"as good as possible\" \u2014 it is \"within tolerance.\" The tolerance is defined by international standards:<\/p>\n\n <div class=\"table-wrap\">\n <div class=\"table-title\">\ud83d\udccf Key Balancing Standards<\/div>\n <div class=\"table-scroll\"><table>\n <thead><tr><th>Standard<\/th><th>Subject<\/th><th>Key Content<\/th><\/tr><\/thead>\n <tbody>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1 \/ ISO 21940-11<\/a><\/td><td>Balance quality grades (G-grades)<\/td><td>G 0.4\u2013G 4000 scale. Formula: U<sub>per<\/sub> = (9 549\u00d7G\u00d7M)\/n. G 6.3 = standard for fans, pumps, motors.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\">ISO 1940-2 \/ ISO 21940-2<\/a><\/td><td>Vocabulary<\/td><td>Definitions: unbalance types, rotor classifications, machine types, quality terms.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a><\/td><td>Industrial fans<\/td><td>BV categories (balance) and FV categories (vibration) specific to fan impellers.<\/td><\/tr>\n <tr><td><a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816 \/ ISO 20816<\/a><\/td><td>Machine vibration evaluation<\/td><td>Measures the operational <em>result<\/em> of balance quality. Zone A\/B\/C\/D classification.<\/td><\/tr>\n <tr><td>ISO 21940-12<\/td><td>Flexible rotors<\/td><td>Multi-speed, multi-plane procedures for rotors above first bending critical speed.<\/td><\/tr>\n <tr><td>ISO 21940-14<\/td><td>Balancing procedures<\/td><td>General procedures for balancing in several planes.<\/td><\/tr>\n <tr><td>API 610 \/ API 617<\/td><td>Petroleum pumps \/ compressors<\/td><td>Reference ISO 1940 G-grades for rotor balance requirements.<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <\/div>\n\n <div class=\"formula-box\">\n <div class=\"formula-label\">ISO 1940-1 Tolerance Formula<\/div>\n <div class=\"formula-main\">U<sub>per<\/sub> = (9 549 \u00d7 G \u00d7 M) \/ n<\/div>\n <div class=\"formula-note\">U<sub>per<\/sub> = permissible residual unbalance (g\u00b7mm) | G = grade (mm\/s) | M = mass (kg) | n = max RPM<\/div>\n <\/div>\n\n <h2 id=\"cases\">Worked Examples<\/h2>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 1: Centrifugal Fan \u2014 Single-Plane Field Balancing<\/div>\n <p><strong>Machine:<\/strong> 22 kW centrifugal supply fan, 1 460 RPM, impeller mass 38 kg. Excessive vibration: 8.2 mm\/s RMS on drive-end bearing. FFT confirms dominant 1\u00d7 peak with stable phase.<\/p>\n <p><strong>Setup:<\/strong> <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> sensor on DE bearing, laser tachometer on shaft. Mode F2 (single-plane \u2014 L\/D < 0.4).<\/p>\n <p><strong>Step 1:<\/strong> Initial run: 8.2 mm\/s at 47\u00b0.<\/p>\n <p><strong>Step 2:<\/strong> Trial weight: 15 g at 0\u00b0 on fan hub, R = 200 mm.<\/p>\n <p><strong>Step 3:<\/strong> Trial run: 5.9 mm\/s at 112\u00b0.<\/p>\n <p><strong>Step 4:<\/strong> Software calculates: correction = <strong>22 g at 198\u00b0<\/strong>, R = 200 mm.<\/p>\n <p><strong>Step 5:<\/strong> Install weld-on weight 22 g at 198\u00b0. Remove trial weight.<\/p>\n <p><strong>Step 6:<\/strong> Verification: <strong>0.9 mm\/s<\/strong>. ISO tolerance G 6.3 \u2192 U<sub>per<\/sub> = 1 570 g\u00b7mm. Achieved: ~180 g\u00b7mm. \u2705 Pass.<\/p>\n <\/div>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 2: Motor-Pump Assembly \u2014 Two-Plane<\/div>\n <p><strong>Machine:<\/strong> 45 kW motor + centrifugal pump, 2 950 RPM, rotor mass 55 kg. Vibration: DE bearing 6.1 mm\/s, NDE bearing 4.8 mm\/s. Phase difference ~140\u00b0 \u2192 dynamic unbalance.<\/p>\n <p><strong>Setup:<\/strong> Balanset-1A two sensors (DE + NDE), mode F3. Correction planes: coupling hub (plane 1) and motor fan end (plane 2).<\/p>\n <p><strong>Runs:<\/strong> Initial \u2192 trial plane 1 (10 g at 0\u00b0) \u2192 trial plane 2 (8 g at 0\u00b0).<\/p>\n <p><strong>Result:<\/strong> Software solves 2\u00d72 matrix. Correction: plane 1 = <strong>18 g at 245\u00b0<\/strong>, plane 2 = <strong>12 g at 68\u00b0<\/strong>.<\/p>\n <p><strong>Verification:<\/strong> DE: <strong>0.7 mm\/s<\/strong>, NDE: <strong>0.5 mm\/s<\/strong>. G 6.3 limit: 1 122 g\u00b7mm. \u2705 Both planes well within tolerance.<\/p>\n <\/div>\n\n <div class=\"example-block\">\n <div class=\"example-title\">Case 3: Crusher Rotor \u2014 Coarse G 16<\/div>\n <p><strong>Machine:<\/strong> Hammer mill crusher, 980 RPM, rotor mass 420 kg. After hammer replacement, vibration increased to 14.5 mm\/s.<\/p>\n <p><strong>Specification:<\/strong> G 16 (heavy-duty, severe conditions). U<sub>per<\/sub> = 9 549 \u00d7 16 \u00d7 420 \/ 980 = <strong>65 500 g\u00b7mm<\/strong>.<\/p>\n <p><strong>Procedure:<\/strong> Single-plane (disc-like rotor). Trial 150 g at 0\u00b0 on rim. Correction: <strong>280 g at 315\u00b0<\/strong>. Weld-on steel plate.<\/p>\n <p><strong>Result:<\/strong> <strong>2.8 mm\/s<\/strong>. Residual ~5 600 g\u00b7mm. \u2705 Well within G 16 limit.<\/p>\n <\/div>\n\n <h2 id=\"related-standards\">Related Topics<\/h2>\n <ul>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a>:<\/strong> G-grade tolerance system \u2014 the acceptance criterion for balancing results.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\">ISO 1940-2<\/a>:<\/strong> Vocabulary \u2014 definitions of all balancing terms.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\">Balance Quality Grade<\/a>:<\/strong> Interactive G-grade calculator.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\">Unbalance<\/a>:<\/strong> The physical condition that balancing corrects.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a>:<\/strong> Fan-specific BV\/FV categories.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/harmonics-vibration\/\">Harmonics<\/a>:<\/strong> Distinguishing 1\u00d7 (unbalance) from 2\u00d7 (misalignment) and other orders.<\/li>\n <li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/natural-frequency\/\">Natural Frequency<\/a>:<\/strong> Rigid\/flexible rotor boundary \u2014 critical for balancing approach.<\/li>\n <\/ul>\n\n <hr style=\"margin:48px 0 24px;border:none;border-top:1px solid var(--border-light);\">\n <p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary Index<\/a><\/p>\n <\/article>\n\n <aside class=\"toc-sidebar\">\n <div class=\"toc-box\">\n <h3>On This Page<\/h3>\n <a href=\"#types\">Static vs. Dynamic<\/a>\n <a class=\"sub\" href=\"#types\">Comparison table<\/a>\n <a href=\"#procedure\">Procedure Steps (6)<\/a>\n <a href=\"#benefits\">Benefits (5)<\/a>\n <a href=\"#definition\">What is Rotor Balancing?<\/a>\n <a href=\"#method\">Influence Coefficient Method<\/a>\n <a class=\"sub\" href=\"#method\">Trial weight selection<\/a>\n <a href=\"#when-to-balance\">When to Balance<\/a>\n <a class=\"sub\" href=\"#when-to-balance\">1\u00d7 vibration signature<\/a>\n <a href=\"#correction\">Correction Methods<\/a>\n <a class=\"sub\" href=\"#correction\">Adding \/ removing mass<\/a>\n <a class=\"sub\" href=\"#correction\">Weight splitting<\/a>\n <a href=\"#field-balancing\">Field Balancing<\/a>\n <a href=\"#standards\">Standards & Tolerances<\/a>\n <a href=\"#cases\">Case Studies (3)<\/a>\n <a href=\"#faq\">FAQ (8 Questions)<\/a>\n <\/div>\n <div class=\"toc-box\" style=\"margin-top:24px;background:var(--navy);border-color:var(--navy);\">\n <h3 style=\"color:#fff;\">Balancing Equipment<\/h3>\n <p style=\"color:rgba(255,255,255,.6);font-size:13px;margin-bottom:12px;\">Complete portable field balancing: 1-plane and 2-plane modes, ISO 1940 tolerance calculator, spectrum analyser, automatic weight splitting, balance reports.<\/p>\n <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" style=\"display:block;padding:8px 14px;background:var(--blue);color:white;border-radius:6px;text-align:center;font-weight:600;font-size:14px;text-decoration:none;margin-bottom:8px;border-left:none;\">Balanset-1A \u2192<\/a>\n <a href=\"https:\/\/vibromera.eu\/product\/balanset-4\/\" style=\"display:block;padding:8px 14px;background:rgba(255,255,255,.1);color:white;border-radius:6px;text-align:center;font-weight:600;font-size:14px;text-decoration:none;border:1px solid rgba(255,255,255,.2);border-left:none;\">Balanset-4 \u2192<\/a>\n <\/div>\n <\/aside>\n <\/div>\n <\/div>\n<\/main>\n\n\n<section class=\"section-bg alt\" id=\"faq\">\n <div class=\"container\" style=\"max-width:1000px;\">\n <div class=\"section-header\"><h2>Frequently Asked Questions \u2014 Rotor Balancing<\/h2><p>Procedures, types, diagnosis, and standards<\/p><\/div>\n <div style=\"display:flex;flex-direction:column;gap:16px;\">\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What is rotor balancing?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">The process of improving mass distribution of a rotating body so that its centre of mass coincides with the geometric rotation axis. Minimises centrifugal forces \u2192 reduces vibration, bearing loads, noise, energy loss. Correction: adding\/removing weight at specific locations\/angles. Acceptance: <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 1940-1<\/a> G-grades.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Static vs. dynamic balancing?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Static (1-plane):<\/strong> corrects displaced CoM \u2014 single heavy spot \u2014 disc-like rotors (L\/D < 0.5). <strong>Dynamic (2-plane):<\/strong> corrects both force + couple \u2014 general case \u2014 elongated rotors. Most real machines need dynamic. When in doubt, use 2-plane.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> How does the trial weight method work?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Measure initial vibration \u2192 attach known trial weight \u2192 measure again \u2192 vector difference = effect of trial. Software calculates influence coefficient, then determines the exact correction mass and angle to cancel the original unbalance. Remove trial, install correction, verify. <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> automates the calculation.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Single-plane or two-plane?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Single-plane: fan impellers, pulleys, grinding wheels, flywheels (L\/D < 0.5). Two-plane: motors, shafts, pumps, rolls, turbines (L\/D > 0.5). Balanset-1A: F2 = single, F3 = two-plane. If bearings vibrate out of phase at 1\u00d7, couple unbalance is present \u2192 two-plane needed.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What ISO standard for tolerances?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\">ISO 21940-11 (ISO 1940-1)<\/a>: G-grade system. G 6.3 = standard for fans\/pumps\/motors. G 2.5 = turbines\/compressors. U<sub>per<\/sub> = (9 549 \u00d7 G \u00d7 M) \/ n. <a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\">ISO 14694<\/a> extends to fan-specific BV categories. <a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816<\/a> evaluates vibration in operation.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> Can I balance in-situ (without removing the rotor)?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\">Yes \u2014 field balancing. A portable <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> uses vibration sensors + tachometer on the installed machine. Trial-weight method determines correction without a dedicated balancing machine. Saves hours of disassembly. Accounts for actual operating conditions (alignment, temperature, foundation).<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> What are common correction methods?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Adding:<\/strong> clip-on, bolt-on, weld-on weights; epoxy\/putty; set screws. <strong>Removing:<\/strong> drilling, milling, grinding. Choice depends on rotor design, temperature, permanence needs. Weight splitting distributes correction between adjacent accessible positions when the exact angle is blocked.<\/div><\/details>\n <details style=\"background:var(--white);border:1px solid var(--border-light);border-radius:var(--radius);overflow:hidden;\"><summary style=\"padding:18px 24px;font-weight:700;font-size:16px;cursor:pointer;color:var(--navy);list-style:none;display:flex;align-items:center;gap:10px;\"><span style=\"color:var(--blue);font-size:18px;\">\u25b8<\/span> How do I know it's unbalance and not misalignment?<\/summary><div style=\"padding:0 24px 18px 52px;font-size:15px;line-height:1.7;color:var(--text);\"><strong>Unbalance:<\/strong> dominant 1\u00d7 peak, radial, stable phase, amplitude \u221d speed\u00b2. <strong><a href=\"https:\/\/vibromera.eu\/glossary\/misalignment\/\">Misalignment<\/a>:<\/strong> significant 2\u00d7 and\/or axial 1\u00d7, phase relationship between bearings, amplitude less speed-dependent. Use Balanset-1A spectrum analyser (F1) to confirm before balancing.<\/div><\/details>\n <\/div>\n <\/div>\n<\/section>\n\n\n<section style=\"padding:32px 0;background:var(--white);border-top:1px solid var(--border-light);\">\n <div class=\"container\" style=\"max-width:1000px;\">\n <h3 style=\"font-family:'DM Serif Display',serif;font-size:22px;color:var(--navy);margin-bottom:20px;\">Related Glossary Articles<\/h3>\n <div style=\"display:grid;grid-template-columns:repeat(3,1fr);gap:16px;\">\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-1\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 1940-1<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">G-grade tolerance system \u2014 the acceptance criterion<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/balance-quality-grade\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Balance Quality Grade<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Interactive G-grade calculator with tolerance tables<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/unbalance\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Unbalance<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">The physical condition that balancing corrects<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-14694\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 14694<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Fan-specific balance & vibration categories<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/iso-1940-2\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">ISO 1940-2<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Vocabulary \u2014 definitions of all balancing terms<\/div><\/a>\n <a href=\"https:\/\/vibromera.eu\/glossary\/natural-frequency\/\" style=\"display:block;padding:18px;background:var(--beige-light);border:1px solid var(--beige-dark);border-radius:var(--radius-sm);text-decoration:none;box-shadow:var(--shadow-sm);\"><div style=\"font-weight:700;color:var(--navy);font-size:15px;margin-bottom:4px;\">Natural Frequency<\/div><div style=\"font-size:13px;color:var(--text-secondary);\">Critical speeds \u2014 rigid vs. flexible rotor boundary<\/div><\/a>\n <\/div>\n <\/div>\n<\/section>\n\n<section class=\"shop-cta\">\n <div class=\"container\">\n <h2>Balance Any Rotor \u2014 In the Field<\/h2>\n <p>Single-plane and two-plane modes, ISO 1940 tolerance calculator, spectrum analyser for diagnosis, automatic weight splitting, and formal balance reports \u2014 all in one portable instrument.<\/p>\n <a href=\"https:\/\/vibromera.eu\/shop\/\" class=\"cta-btn\">Browse Balancing Equipment \u2192<\/a>\n <\/div>\n<\/section>\n\n<footer class=\"page-footer\">\n <div class=\"container\"><p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary<\/a> | <a href=\"https:\/\/vibromera.eu\/\">vibromera.eu<\/a><\/p><\/div>\n<\/footer>\n\n<\/body>\n<\/html><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Um guia completo sobre balanceamento de rotores. Aprenda sobre balanceamento est\u00e1tico vs. din\u00e2mico, procedimentos de plano \u00fanico e duplo e a import\u00e2ncia de normas como a ISO 21940.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[109,112],"tags":[],"class_list":["post-20632","glossary","type-glossary","status-publish","hentry","category-glossary","category-iso-standards"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":4,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632\/revisions"}],"predecessor-version":[{"id":101501,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/glossary\/20632\/revisions\/101501"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/media?parent=20632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/categories?post=20632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/tags?post=20632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}