{"id":100043,"date":"2026-02-15T20:08:01","date_gmt":"2026-02-15T20:08:01","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100043"},"modified":"2026-02-15T20:08:01","modified_gmt":"2026-02-15T20:08:01","slug":"bolt-tightening-torque","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/bolt-tightening-torque\/","title":{"rendered":"Kalkulator for tiltrekkingsmoment for bolter | Gratis nettverkt\u00f8y | ISO 16047 og VDI 2230"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Bolt Tightening Torque Calculator\",\"alternateName\":[\"Bolt Torque Calculator\",\"Fastener Torque Calculator\",\"Preload Force Calculator\"],\"description\":\"Free online engineering calculator for determining bolt tightening torque based on ISO 16047 and VDI 2230 standards.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/bolt-tightening-torque\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"softwareVersion\":\"3.0\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"USD\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2024-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"Metric bolt sizes M3-M48 (coarse and fine pitch)\",\"Imperial bolt sizes 1\/4\\\" to 1-1\/4\\\"\",\"Property classes 4.6, 5.6, 8.8, 10.9, 12.9\",\"SAE grades 2, 5, 8\",\"Multiple lubrication conditions\",\"K-factor calculation\",\"Preload force calculation\",\"Kellermann-Klein detailed analysis\",\"Step-by-step tightening sequence\",\"Visual bolt pattern diagrams\",\"Metric\/Imperial unit conversion\",\"Auto-calculation on input change\",\"Copy results to clipboard\"]}<\/script>\n\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What is the formula for calculating bolt tightening torque?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"T = K \u00d7 F \u00d7 d, where K is the torque coefficient (0.10\u20130.25), F is target preload force (N), and d is nominal bolt diameter (m).\"}},{\"@type\":\"Question\",\"name\":\"What is K-factor in bolt tightening?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"K-factor combines thread and bearing surface friction. Typical values: dry 0.20-0.25, oiled 0.14-0.18, MoS\u2082 0.10-0.12, PTFE 0.08-0.10.\"}},{\"@type\":\"Question\",\"name\":\"What is the recommended preload for bolts?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Typically 65-75% of yield strength for standard applications. F = S \u00d7 As \u00d7 \u03b7.\"}},{\"@type\":\"Question\",\"name\":\"How does lubrication affect bolt torque?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Lubrication reduces K-factor significantly. Using wrong K-factor causes over- or under-tightening.\"}},{\"@type\":\"Question\",\"name\":\"What is the correct bolt tightening sequence?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Tighten in multiple passes using cross\/star pattern: snug \u2192 30% \u2192 70% \u2192 100%.\"}},{\"@type\":\"Question\",\"name\":\"What is the Kellermann-Klein equation?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"T = F \u00d7 [P\/(2\u03c0) + 1.154\u00b7\u03bcth\u00b7d\u2082 + \u03bcb\u00b7(Do+dh)\/4]. 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Supports coarse &amp; fine pitch metric threads, imperial UNC, and multiple lubrication conditions.<\/p>\n        <div class=\"vc-badges\"><span class=\"vc-badge\">ISO 898<\/span><span class=\"vc-badge\">ISO 16047<\/span><span class=\"vc-badge\">VDI 2230<\/span><span class=\"vc-badge\">ASME B1.1<\/span><\/div>\n    <\/header>\n    <div class=\"vc-card\">\n        <div class=\"vc-unit-bar\"><button type=\"button\" class=\"vc-unit-btn vc-active\" data-system=\"metric\">Metric (N\u00b7m, kN)<\/button><button type=\"button\" class=\"vc-unit-btn\" data-system=\"imperial\">Imperial (lb\u00b7ft, lbf)<\/button><\/div>\n        <form class=\"vc-form\" id=\"vc-torque-form\" aria-label=\"Bolt torque calculation parameters\"><div class=\"vc-form-grid\">\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-bolt-size\">Bolt Size<\/label><select class=\"vc-select\" id=\"vc-bolt-size\"><optgroup label=\"Metric \u2014 Coarse Pitch (ISO 261)\"><option value=\"M3\">M3 \u00d7 0.5<\/option><option value=\"M4\">M4 \u00d7 0.7<\/option><option value=\"M5\">M5 \u00d7 0.8<\/option><option value=\"M6\">M6 \u00d7 1.0<\/option><option value=\"M8\">M8 \u00d7 1.25<\/option><option value=\"M10\">M10 \u00d7 1.5<\/option><option value=\"M12\" selected>M12 \u00d7 1.75<\/option><option value=\"M14\">M14 \u00d7 2.0<\/option><option value=\"M16\">M16 \u00d7 2.0<\/option><option value=\"M20\">M20 \u00d7 2.5<\/option><option value=\"M24\">M24 \u00d7 3.0<\/option><option value=\"M30\">M30 \u00d7 3.5<\/option><option value=\"M36\">M36 \u00d7 4.0<\/option><option value=\"M42\">M42 \u00d7 4.5<\/option><option value=\"M48\">M48 \u00d7 5.0<\/option><\/optgroup><optgroup label=\"Metric \u2014 Fine Pitch (ISO 261)\"><option value=\"M8x1\">M8 \u00d7 1.0<\/option><option value=\"M10x1\">M10 \u00d7 1.0<\/option><option value=\"M10x1.25\">M10 \u00d7 1.25<\/option><option value=\"M12x1.25\">M12 \u00d7 1.25<\/option><option value=\"M12x1.5\">M12 \u00d7 1.5<\/option><option value=\"M14x1.5\">M14 \u00d7 1.5<\/option><option value=\"M16x1.5\">M16 \u00d7 1.5<\/option><option value=\"M20x1.5\">M20 \u00d7 1.5<\/option><option value=\"M20x2\">M20 \u00d7 2.0<\/option><option value=\"M24x2\">M24 \u00d7 2.0<\/option><option value=\"M30x2\">M30 \u00d7 2.0<\/option><option value=\"M36x3\">M36 \u00d7 3.0<\/option><\/optgroup><optgroup label=\"Imperial \u2014 UNC\"><option value=\"1\/4-UNC\">1\/4&#8243; \u2014 20 UNC<\/option><option value=\"5\/16-UNC\">5\/16&#8243; \u2014 18 UNC<\/option><option value=\"3\/8-UNC\">3\/8&#8243; \u2014 16 UNC<\/option><option value=\"7\/16-UNC\">7\/16&#8243; \u2014 14 UNC<\/option><option value=\"1\/2-UNC\">1\/2&#8243; \u2014 13 UNC<\/option><option value=\"9\/16-UNC\">9\/16&#8243; \u2014 12 UNC<\/option><option value=\"5\/8-UNC\">5\/8&#8243; \u2014 11 UNC<\/option><option value=\"3\/4-UNC\">3\/4&#8243; \u2014 10 UNC<\/option><option value=\"7\/8-UNC\">7\/8&#8243; \u2014 9 UNC<\/option><option value=\"1-UNC\">1&#8243; \u2014 8 UNC<\/option><option value=\"1-1\/8-UNC\">1-1\/8&#8243; \u2014 7 UNC<\/option><option value=\"1-1\/4-UNC\">1-1\/4&#8243; \u2014 7 UNC<\/option><\/optgroup><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-bolt-grade\">Property Class \/ Grade<\/label><select class=\"vc-select\" id=\"vc-bolt-grade\"><optgroup label=\"Metric (ISO 898-1)\"><option value=\"4.6\">4.6 \u2014 Rp 240 MPa<\/option><option value=\"5.6\">5.6 \u2014 Rp 300 MPa<\/option><option value=\"8.8\" selected>8.8 \u2014 Rp 640 MPa<\/option><option value=\"10.9\">10.9 \u2014 Rp 900 MPa<\/option><option value=\"12.9\">12.9 \u2014 Rp 1080 MPa<\/option><\/optgroup><optgroup label=\"Imperial (SAE J429)\"><option value=\"SAE2\">Grade 2 \u2014 57 ksi<\/option><option value=\"SAE5\">Grade 5 \u2014 92 ksi<\/option><option value=\"SAE8\">Grade 8 \u2014 130 ksi<\/option><\/optgroup><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-strength-basis\">Strength Basis <span class=\"vc-label-hint\">(strict mode)<\/span><\/label><select class=\"vc-select\" id=\"vc-strength-basis\"><option value=\"yield\" selected>Yield strength Rp (default)<\/option><option value=\"proof\">Proof stress Sp (ISO 898-1)<\/option><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-lubrication\">Lubrication <span class=\"vc-label-hint\">(affects K-factor)<\/span><\/label><select class=\"vc-select\" id=\"vc-lubrication\"><option value=\"dry\">Dry (K \u2248 0.22)<\/option><option value=\"oil\" selected>Light oil (K \u2248 0.16)<\/option><option value=\"moly\">MoS\u2082 grease (K \u2248 0.11)<\/option><option value=\"ptfe\">PTFE \/ Teflon (K \u2248 0.09)<\/option><option value=\"zinc\">Zinc plated (K \u2248 0.18)<\/option><option value=\"cadmium\">Cadmium plated (K \u2248 0.17)<\/option><option value=\"antiseize\">Anti-seize compound (K \u2248 0.12)<\/option><option value=\"wax\">Wax patch (K \u2248 0.10)<\/option><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-preload\">Target Preload <span class=\"vc-label-hint\">(% of <span id=\"vc-preload-basis-hint\">Rp<\/span>)<\/span><\/label><select class=\"vc-select\" id=\"vc-preload\"><option value=\"50\">50% \u2014 Light duty \/ vibration<\/option><option value=\"65\">65% \u2014 Moderate duty<\/option><option value=\"75\" selected>75% \u2014 Standard (recommended)<\/option><option value=\"85\">85% \u2014 High performance<\/option><option value=\"90\">90% \u2014 Maximum (critical joints)<\/option><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-joint-type\">Joint Type <span class=\"vc-label-hint\">(informational)<\/span><\/label><select class=\"vc-select\" id=\"vc-joint-type\"><option value=\"hard\" selected>Hard joint (metal to metal)<\/option><option value=\"soft\">Soft joint (with gasket)<\/option><option value=\"tapped\">Tapped hole (blind)<\/option><option value=\"through\">Through hole with nut<\/option><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-method\">Tightening Method <span class=\"vc-label-hint\">(affects range)<\/span><\/label><select class=\"vc-select\" id=\"vc-method\"><option value=\"manual\" selected>Torque wrench (\u00b15%)<\/option><option value=\"digital\">Digital wrench (\u00b12%)<\/option><option value=\"pneumatic\">Pneumatic tool (\u00b120%)<\/option><option value=\"electric\">Electric tool (\u00b110%)<\/option><option value=\"hydraulic\">Hydraulic tensioner (\u00b15%)<\/option><\/select><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-bolt-count\">Number of Bolts <span class=\"vc-label-hint\">(for pattern)<\/span><\/label><select class=\"vc-select\" id=\"vc-bolt-count\"><option value=\"1\">1 bolt<\/option><option value=\"2\">2 bolts<\/option><option value=\"4\" selected>4 bolts<\/option><option value=\"6\">6 bolts<\/option><option value=\"8\">8 bolts<\/option><option value=\"12\">12 bolts<\/option><option value=\"16\">16 bolts<\/option><\/select><\/div>\n        <\/div><\/form>\n        <div class=\"vc-results\" id=\"vc-results\">\n            <div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Results<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\" title=\"Copy results\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy<\/button><\/div>\n            <p class=\"vc-strength-note\" id=\"vc-strength-note\"><\/p>\n            <div class=\"vc-result-grid\">\n                <div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Recommended Torque<\/div><div class=\"vc-rcard-value\" id=\"vc-r-torque\">\u2014<\/div><\/div>\n                <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Preload Force<\/div><div class=\"vc-rcard-value\" id=\"vc-r-preload\">\u2014<\/div><\/div>\n                <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">K-Factor<\/div><div class=\"vc-rcard-value\" id=\"vc-r-kfactor\">\u2014<\/div><\/div>\n                <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Stress Area<\/div><div class=\"vc-rcard-value\" id=\"vc-r-area\">\u2014<\/div><\/div>\n            <\/div>\n            <div class=\"vc-torque-bar\"><div class=\"vc-torque-bar-label\">Torque Range (based on tightening method accuracy)<\/div><div class=\"vc-bar-track\"><div class=\"vc-bar-zone vc-bar-nom\" id=\"vc-bar-nom\"><\/div><\/div><div class=\"vc-bar-labels\"><span id=\"vc-bar-min\">\u2014<\/span><span id=\"vc-bar-mid\">\u2014<\/span><span id=\"vc-bar-max\">\u2014<\/span><\/div><\/div>\n            <div class=\"vc-sequence\"><div class=\"vc-sequence-header\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2\"\/><rect x=\"9\" y=\"3\" width=\"6\" height=\"4\" rx=\"1\"\/><\/svg> Tightening Sequence<\/div><ul class=\"vc-step-list\"><li class=\"vc-step-item vc-step-1\"><span class=\"vc-step-num\">1<\/span><span class=\"vc-step-text\">Hand-tighten all bolts until <strong>snug<\/strong><\/span><\/li><li class=\"vc-step-item vc-step-2\"><span class=\"vc-step-num\">2<\/span><span class=\"vc-step-text\">Tighten to <strong id=\"vc-s30\">\u2014<\/strong> (30% torque) in pattern<\/span><\/li><li class=\"vc-step-item vc-step-3\"><span class=\"vc-step-num\">3<\/span><span class=\"vc-step-text\">Tighten to <strong id=\"vc-s70\">\u2014<\/strong> (70% torque) in pattern<\/span><\/li><li class=\"vc-step-item vc-step-4\"><span class=\"vc-step-num\">4<\/span><span class=\"vc-step-text\">Tighten to <strong id=\"vc-s100\">\u2014<\/strong> (100% torque) \u2014 smooth motion<\/span><\/li><\/ul><\/div>\n            <div class=\"vc-patterns\" id=\"vc-patterns-section\"><div class=\"vc-patterns-title\">Recommended Tightening Pattern<\/div><div id=\"vc-pattern-display\"><\/div><\/div>\n        <\/div>\n    <\/div>\n    <div class=\"vc-section vc-open\" id=\"vc-sec-theory\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Reference Data<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\">\n        <h3>Torque Calculation Formula<\/h3><p>The required tightening torque is calculated using the simplified VDI 2230 nut-factor method:<\/p><div class=\"vc-formula-box\">T = K \u00d7 F \u00d7 d<\/div><ul><li><strong>T<\/strong> \u2014 tightening torque (N\u00b7m)<\/li><li><strong>K<\/strong> \u2014 torque coefficient \/ nut factor (0.10\u20130.25)<\/li><li><strong>F<\/strong> \u2014 target preload force (N)<\/li><li><strong>d<\/strong> \u2014 nominal bolt diameter (m)<\/li><\/ul>\n        <h3>Preload Force<\/h3><div class=\"vc-formula-box\">F = S \u00d7 A<sub>s<\/sub> \u00d7 \u03b7<\/div><ul><li><strong>S<\/strong> \u2014 strength basis: <strong>Rp<\/strong> (yield) or <strong>Sp<\/strong> (proof stress)<\/li><li><strong>A<sub>s<\/sub><\/strong> \u2014 tensile stress area (mm\u00b2)<\/li><li><strong>\u03b7<\/strong> \u2014 utilization factor (0.50\u20130.90)<\/li><\/ul>\n        <h3>Kellermann-Klein Equation<\/h3><div class=\"vc-formula-box\">T = F \u00d7 [ P\/(2\u03c0) + 1.154\u00b7\u03bc<sub>th<\/sub>\u00b7d\u2082 + \u03bc<sub>b<\/sub>\u00b7(D<sub>o<\/sub>+d<sub>h<\/sub>)\/4 ]<\/div>\n        <h3>K-Factor Reference<\/h3><table class=\"vc-table\"><thead><tr><th>Surface Condition<\/th><th>K-factor<\/th><th>Notes<\/th><\/tr><\/thead><tbody><tr><td>Dry<\/td><td>0.20\u20130.25<\/td><td>High scatter<\/td><\/tr><tr><td>Light oil<\/td><td>0.14\u20130.18<\/td><td>Most common<\/td><\/tr><tr><td>MoS\u2082<\/td><td>0.10\u20130.12<\/td><td>High loads, stainless<\/td><\/tr><tr><td>PTFE<\/td><td>0.08\u20130.10<\/td><td>Caution: over-torque<\/td><\/tr><tr><td>Zinc plated<\/td><td>0.17\u20130.20<\/td><td>Depends on coating<\/td><\/tr><tr><td>Anti-seize<\/td><td>0.11\u20130.13<\/td><td>High-temperature<\/td><\/tr><tr><td>Wax patch<\/td><td>0.09\u20130.11<\/td><td>Automotive OEM<\/td><\/tr><\/tbody><\/table>\n        <h3>Bolt Property Classes (ISO 898-1)<\/h3><table class=\"vc-table\"><thead><tr><th>Class<\/th><th>R<sub>m<\/sub><\/th><th>R<sub>p<\/sub><\/th><th>S<sub>p<\/sub><\/th><th>Application<\/th><\/tr><\/thead><tbody><tr><td>4.6<\/td><td>400<\/td><td>240<\/td><td>225<\/td><td>Non-critical<\/td><\/tr><tr><td>5.6<\/td><td>500<\/td><td>300<\/td><td>280<\/td><td>General<\/td><\/tr><tr><td>8.8<\/td><td>800<\/td><td>640<\/td><td>580\/600<\/td><td>Standard structural<\/td><\/tr><tr><td>10.9<\/td><td>1040<\/td><td>940<\/td><td>830<\/td><td>High-strength<\/td><\/tr><tr><td>12.9<\/td><td>1220<\/td><td>1100<\/td><td>970<\/td><td>Critical, max load<\/td><\/tr><\/tbody><\/table>\n        <h3>Practical Examples<\/h3><div class=\"vc-example-box\"><div class=\"vc-example-title\">Pump Flange \u2014 M12 \u00d7 1.75, class 8.8, oiled<\/div><p>K=0.16, F=640\u00d784.3\u00d70.75=40,464 N \u2192 T=0.16\u00d740464\u00d70.012=<strong>77.7 N\u00b7m<\/strong><\/p><\/div><div class=\"vc-example-box\"><div class=\"vc-example-title\">Gearbox \u2014 M20 \u00d7 2.5, class 10.9, anti-seize<\/div><p>K=0.12, F=900\u00d7245\u00d70.75=165,375 N \u2192 T=0.12\u00d7165375\u00d70.020=<strong>397 N\u00b7m<\/strong><\/p><\/div>\n        <div class=\"vc-warning-box\"><ul><li><strong>Over-torquing<\/strong> strips threads or fractures bolt<\/li><li><strong>Under-torquing<\/strong> \u2192 loosening, leaks, fatigue failure<\/li><li>Calibrate torque wrenches annually<\/li><li>Clean threads before assembly<\/li><li>Do not reuse class 10.9+ bolts<\/li><li>This is an engineering estimate \u2014 test per ISO 16047 for critical joints<\/li><\/ul><\/div>\n    <\/div><\/div><\/div>\n    <div class=\"vc-section\" id=\"vc-sec-faq\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div><\/div>\n    <footer class=\"vc-footer\"><p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p><p style=\"font-size:12px;margin-top:4px;\">Based on ISO 16047:2005, VDI 2230:2015, ISO 898-1<\/p><div class=\"vc-footer-links\"><a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a><a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a><\/div><\/footer>\n<\/div>\n<script>\n(function(){\n'use strict';\nvar boltData={'M3':{d:3,As:5.03,P:0.5},'M4':{d:4,As:8.78,P:0.7},'M5':{d:5,As:14.2,P:0.8},'M6':{d:6,As:20.1,P:1.0},'M8':{d:8,As:36.6,P:1.25},'M10':{d:10,As:58.0,P:1.5},'M12':{d:12,As:84.3,P:1.75},'M14':{d:14,As:115,P:2.0},'M16':{d:16,As:157,P:2.0},'M20':{d:20,As:245,P:2.5},'M24':{d:24,As:353,P:3.0},'M30':{d:30,As:561,P:3.5},'M36':{d:36,As:817,P:4.0},'M42':{d:42,As:1120,P:4.5},'M48':{d:48,As:1470,P:5.0},'M8x1':{d:8,As:39.2,P:1.0},'M10x1':{d:10,As:64.5,P:1.0},'M10x1.25':{d:10,As:61.2,P:1.25},'M12x1.25':{d:12,As:92.1,P:1.25},'M12x1.5':{d:12,As:88.1,P:1.5},'M14x1.5':{d:14,As:125,P:1.5},'M16x1.5':{d:16,As:167,P:1.5},'M20x1.5':{d:20,As:272,P:1.5},'M20x2':{d:20,As:258,P:2.0},'M24x2':{d:24,As:384,P:2.0},'M30x2':{d:30,As:621,P:2.0},'M36x3':{d:36,As:865,P:3.0},'1\/4-UNC':{d:6.35,As:20.5,P:1.27},'5\/16-UNC':{d:7.94,As:33.8,P:1.41},'3\/8-UNC':{d:9.53,As:50.0,P:1.59},'7\/16-UNC':{d:11.11,As:68.6,P:1.81},'1\/2-UNC':{d:12.7,As:91.5,P:1.95},'9\/16-UNC':{d:14.29,As:117.4,P:2.12},'5\/8-UNC':{d:15.88,As:145.8,P:2.31},'3\/4-UNC':{d:19.05,As:215.8,P:2.54},'7\/8-UNC':{d:22.23,As:297.9,P:2.82},'1-UNC':{d:25.4,As:390.8,P:3.18},'1-1\/8-UNC':{d:28.58,As:492.4,P:3.63},'1-1\/4-UNC':{d:31.75,As:625.2,P:3.63}};\nvar gradeRp={'4.6':240,'5.6':300,'8.8':640,'10.9':900,'12.9':1080,'SAE2':390,'SAE5':635,'SAE8':895};\nvar gradeSp={'4.6':225,'5.6':280,'8.8':{le16:580,gt16:600},'10.9':830,'12.9':970};\nvar kFactors={'dry':0.22,'oil':0.16,'moly':0.11,'ptfe':0.09,'zinc':0.18,'cadmium':0.17,'antiseize':0.12,'wax':0.10};\nvar methodScatter={'manual':0.05,'digital':0.02,'pneumatic':0.20,'electric':0.10,'hydraulic':0.05};\nvar unitSystem='metric';\nfunction $(id){return document.getElementById(id)}\nfunction fmt(n,d){if(d===undefined)d=2;if(isNaN(n))return'\u2014';var f=n.toFixed(d);return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}\nfunction getSp(grade,diam){var sp=gradeSp[grade];if(!sp)return null;if(typeof sp==='number')return sp;if(grade==='8.8')return diam>16?sp.gt16:sp.le16;return null}\nfunction calculate(){var bolt=boltData[$('vc-bolt-size').value];var grade=$('vc-bolt-grade').value;var rp=gradeRp[grade];if(!bolt||!rp)return;var basis=$('vc-strength-basis').value;var eta=parseFloat($('vc-preload').value)\/100;var lub=$('vc-lubrication').value;var method=$('vc-method').value;var S=rp,label='Rp',note='';if(basis==='proof'){var sp=getSp(grade,bolt.d);if(sp){S=sp;label='Sp';note='Using proof stress Sp per ISO 898-1.';}else{note='Sp not defined \u2014 using Rp.';}}var F=S*bolt.As*eta;var K=kFactors[lub]||0.16;var T=K*F*(bolt.d\/1000);var scatter=methodScatter[method]||0.05;var Tmin=T*(1-scatter);var Tmax=T*(1+scatter);displayResults(T,F,K,Tmin,Tmax,bolt.As,S,label,note)}\nfunction displayResults(T,F,K,Tmin,Tmax,As,S,label,note){var ts,ps,rMin,rMid,rMax,s30,s70,s100;if(unitSystem==='metric'){ts=(T>=1000?fmt(T,0):fmt(T,1))+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';ps=(F>=1000?fmt(F\/1000,1)+' <span class=\"vc-rcard-unit\">kN<\/span>':fmt(F,0)+' <span class=\"vc-rcard-unit\">N<\/span>');rMin=fmt(Tmin,1);rMid=fmt(T,1);rMax=fmt(Tmax,1);s30=fmt(T*0.3,1)+' N\u00b7m';s70=fmt(T*0.7,1)+' N\u00b7m';s100=fmt(T,1)+' N\u00b7m'}else{var Tl=T*0.737562,Fl=F*0.224809;ts=(Tl<10?fmt(Tl,2):fmt(Tl,1))+' <span class=\"vc-rcard-unit\">lb\u00b7ft<\/span>';ps=fmt(Fl,0)+' <span class=\"vc-rcard-unit\">lbf<\/span>';rMin=fmt(Tmin*0.737562,1);rMid=fmt(Tl,1);rMax=fmt(Tmax*0.737562,1);s30=fmt(Tl*0.3,1)+' lb\u00b7ft';s70=fmt(Tl*0.7,1)+' lb\u00b7ft';s100=fmt(Tl,1)+' lb\u00b7ft'}$('vc-r-torque').innerHTML=ts;$('vc-r-preload').innerHTML=ps;$('vc-r-kfactor').textContent=fmt(K,3);$('vc-r-area').innerHTML=fmt(As,1)+' <span class=\"vc-rcard-unit\">mm\u00b2<\/span>';$('vc-strength-note').innerHTML='<strong>'+label+'<\/strong> = '+fmt(S,0)+' MPa'+(note?' \u00b7 '+note:'');$('vc-bar-nom').style.left='30%';$('vc-bar-nom').style.width='40%';var u=unitSystem==='metric'?' N\u00b7m':' lb\u00b7ft';$('vc-bar-min').textContent=rMin+u;$('vc-bar-mid').textContent=rMid+u;$('vc-bar-max').textContent=rMax+u;$('vc-s30').textContent=s30;$('vc-s70').textContent=s70;$('vc-s100').textContent=s100;renderPattern(parseInt($('vc-bolt-count').value)||4);$('vc-results').classList.add('vc-visible')}\nfunction renderPattern(n){var c=$('vc-pattern-display');if(n<=1){c.innerHTML='<p style=\"font-size:13px;color:var(--vc-ink-muted)\">Single bolt \u2014 no pattern needed.<\/p>';return}var pats={2:{order:[1,2],name:'Alternate'},4:{order:[1,3,2,4],name:'Cross'},6:{order:[1,4,2,5,3,6],name:'Star'},8:{order:[1,5,3,7,2,6,4,8],name:'Opposite pairs'},12:{order:[1,7,4,10,2,8,5,11,3,9,6,12],name:'Star'},16:{order:[1,9,5,13,3,11,7,15,2,10,6,14,4,12,8,16],name:'Star'}};var pat=pats[n]||pats[4];var sz=160,cx=sz\/2,cy=sz\/2,r=52;var svg='<svg viewBox=\"0 0 '+sz+' '+sz+'\" style=\"width:100%;max-width:180px;\">';svg+='<circle cx=\"'+cx+'\" cy=\"'+cy+'\" r=\"'+(r+14)+'\" fill=\"none\" stroke=\"#d9d4cc\" stroke-width=\"1.5\" stroke-dasharray=\"4 3\"\/>';svg+='<circle cx=\"'+cx+'\" cy=\"'+cy+'\" r=\"20\" fill=\"none\" stroke=\"#d9d4cc\" stroke-width=\"1\"\/>';var bp=[];for(var i=0;i<n;i++){var a=(2*Math.PI*i\/n)-Math.PI\/2;bp.push({x:cx+r*Math.cos(a),y:cy+r*Math.sin(a)})}for(var j=0;j<pat.order.length-1;j++){var fi=pat.order[j]-1,ti=pat.order[j+1]-1;if(fi<bp.length&&ti<bp.length){var fr=bp[fi],to=bp[ti],dx=to.x-fr.x,dy=to.y-fr.y,ln=Math.sqrt(dx*dx+dy*dy);if(ln>0){var nx=dx\/ln,ny=dy\/ln,pd=10;svg+='<line x1=\"'+(fr.x+nx*pd).toFixed(1)+'\" y1=\"'+(fr.y+ny*pd).toFixed(1)+'\" x2=\"'+(to.x-nx*pd).toFixed(1)+'\" y2=\"'+(to.y-ny*pd).toFixed(1)+'\" stroke=\"#b0a89e\" stroke-width=\"0.8\" stroke-dasharray=\"3 2\"\/>'}}}for(var k=0;k<bp.length;k++){var p=bp[k],pn=k+1,to2=pat.order.indexOf(pn)+1;var col=to2<=Math.ceil(n\/2)?'#c85a2a':'#2a5c8c';svg+='<circle cx=\"'+p.x.toFixed(1)+'\" cy=\"'+p.y.toFixed(1)+'\" r=\"9\" fill=\"'+col+'\" opacity=\"0.12\"\/>';svg+='<circle cx=\"'+p.x.toFixed(1)+'\" cy=\"'+p.y.toFixed(1)+'\" r=\"9\" fill=\"none\" stroke=\"'+col+'\" stroke-width=\"1.5\"\/>';svg+='<text x=\"'+p.x.toFixed(1)+'\" y=\"'+(p.y+3.5).toFixed(1)+'\" text-anchor=\"middle\" font-family=\"monospace\" font-size=\"9\" font-weight=\"600\" fill=\"'+col+'\">'+pn+'<\/text>'}svg+='<\/svg>';c.innerHTML='<div style=\"text-align:center\">'+svg+'<div class=\"vc-pattern-label\" style=\"margin-top:8px;font-weight:600\">'+n+' bolts \u2014 '+pat.name+'<\/div><div class=\"vc-pattern-label\" style=\"margin-top:2px\">Sequence: '+pat.order.join(' \u2192 ')+'<\/div><\/div>'}\nfunction copyResults(){var t='Bolt Torque: '+$('vc-r-torque').textContent+'\\nPreload: '+$('vc-r-preload').textContent+'\\nK-factor: '+$('vc-r-kfactor').textContent+'\\nvibromera.eu\/calculators\/bolt-tightening-torque\/';if(navigator.clipboard){navigator.clipboard.writeText(t).then(function(){var b=$('vc-copy-btn');b.classList.add('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';setTimeout(function(){b.classList.remove('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy'},2000)})}}\nvar faqData=[{q:'What is the formula for calculating bolt tightening torque?',a:'<p><strong>T = K \u00d7 F \u00d7 d<\/strong>, where K is the torque coefficient (0.10\u20130.25), F is preload force (N), d is nominal diameter (m).<\/p><p>For detailed analysis: Kellermann-Klein equation separates thread and bearing friction.<\/p>'},{q:'What is K-factor in bolt tightening?',a:'<p>K-factor combines thread and bearing friction. Determined per ISO 16047 at 75% proof load.<\/p><ul><li>Dry: 0.20\u20130.25<\/li><li>Oil: 0.14\u20130.18<\/li><li>MoS\u2082: 0.10\u20130.12<\/li><li>PTFE: 0.08\u20130.10<\/li><\/ul>'},{q:'What is the recommended preload percentage?',a:'<p>Standard: <strong>75% of Rp<\/strong>. Range: 50% (light duty) to 90% (critical). For strict design, use Sp instead of Rp.<\/p>'},{q:'How does lubrication affect bolt torque?',a:'<p>Lubrication dramatically reduces K-factor. Dry K\u22480.22 vs PTFE K\u22480.09. Using dry torque on lubricated bolt = <strong>severe over-tightening<\/strong>.<\/p>'},{q:'What is the correct tightening sequence?',a:'<p>Multiple passes with cross\/star pattern: snug \u2192 30% \u2192 70% \u2192 100%. Re-check after 24h operation.<\/p>'},{q:'What is the Kellermann-Klein equation?',a:'<p>T = F \u00d7 [P\/(2\u03c0) + 1.154\u00b7\u03bc<sub>th<\/sub>\u00b7d\u2082 + \u03bc<sub>b<\/sub>\u00b7(D<sub>o<\/sub>+d<sub>h<\/sub>)\/4]. Separates thread friction from bearing friction.<\/p>'},{q:'Coarse vs fine pitch threads?',a:'<p>Fine pitch = larger stress area, higher preload, better vibration resistance, but higher strip risk. Used in automotive, aerospace.<\/p>'},{q:'Can I reuse high-strength bolts?',a:'<p>Class 10.9+ should not be reused after design preload. Torque-to-yield bolts are single-use. Class 8.8 may be reused if undamaged.<\/p>'},{q:'How accurate is torque wrench tightening?',a:'<p>Tool: click \u00b15%, digital \u00b12%. But friction variation causes \u00b125-30% preload scatter. For critical joints: torque-angle or hydraulic tensioning.<\/p>'},{q:'ISO 16047 vs VDI 2230?',a:'<p>ISO 16047 = <em>testing<\/em> (measure K-factor on real fasteners). VDI 2230 = <em>design<\/em> (calculate required bolt, preload, torque). Complementary.<\/p>'}];\nfunction renderFAQ(){var l=$('vc-faq-list'),h='';faqData.forEach(function(f,i){h+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});l.innerHTML=h;l.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(b)b.closest('.vc-faq-item').classList.toggle('vc-open')})}\nfunction init(){var form=$('vc-torque-form');form.querySelectorAll('select').forEach(function(s){s.addEventListener('change',calculate)});$('vc-strength-basis').addEventListener('change',function(){$('vc-preload-basis-hint').textContent=this.value==='proof'?'Sp':'Rp'});document.querySelectorAll('.vc-unit-btn').forEach(function(b){b.addEventListener('click',function(){document.querySelectorAll('.vc-unit-btn').forEach(function(x){x.classList.remove('vc-active')});this.classList.add('vc-active');unitSystem=this.getAttribute('data-system');if($('vc-results').classList.contains('vc-visible'))calculate()})});$('vc-copy-btn').addEventListener('click',copyResults);document.querySelectorAll('.vc-section-toggle').forEach(function(b){b.addEventListener('click',function(){var s=this.closest('.vc-section');s.classList.toggle('vc-open');this.setAttribute('aria-expanded',s.classList.contains('vc-open'))})});renderFAQ();calculate()}\nif(document.readyState==='loading')document.addEventListener('DOMContentLoaded',init);else init();\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis online boltmomentkalkulator basert p\u00e5 ISO 16047 og VDI 2230 standarder. Beregn tiltrekkingsmoment, forspenningskraft og K-faktor for metriske M3-M48 (grov og fin stigning) og tommerbolter. Inkluderer friksjonskoeffisienter, egenskapsklasser 4,6-12,9 og trinnvise tiltrekkingssekvenser.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100043","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100043","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":1,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100043\/revisions"}],"predecessor-version":[{"id":100354,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100043\/revisions\/100354"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/media?parent=100043"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/categories?post=100043"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/tags?post=100043"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}