{"id":100040,"date":"2026-02-15T20:07:51","date_gmt":"2026-02-15T20:07:51","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100040"},"modified":"2026-02-15T20:07:51","modified_gmt":"2026-02-15T20:07:51","slug":"bolt-preload-calculator","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bn\/calculators\/bolt-preload-calculator\/","title":{"rendered":"\u09ac\u09cb\u09b2\u09cd\u099f \u09aa\u09cd\u09b0\u09bf\u09b2\u09cb\u09a1 \u09ab\u09cb\u09b0\u09cd\u09b8 \u0995\u09cd\u09af\u09be\u09b2\u0995\u09c1\u09b2\u09c7\u099f\u09b0 | ISO 898-1 | \u09ac\u09bf\u09a8\u09be\u09ae\u09c2\u09b2\u09cd\u09af\u09c7 \u0985\u09a8\u09b2\u09be\u0987\u09a8 \u099f\u09c1\u09b2"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Bolt Preload Force Calculator\",\"alternateName\":[\"Bolt Clamping Force Calculator\",\"Assembly Preload Calculator\"],\"description\":\"Free online engineering calculator for bolt preload force. Enter bolt size, property class, and utilization percentage to get assembly preload per ISO 898-1.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/bolt-preload-calculator\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2025-01-01\",\"dateModified\":\"2026-02-15\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"Metric bolt sizes M3\u2013M64\",\"Property classes 4.6 to 12.9\",\"Adjustable utilization factor\",\"Torque estimation\",\"Auto-calculation\"],\"keywords\":\"bolt preload, clamping force, utilization factor, assembly tension, ISO 898-1\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What is bolt preload force?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Bolt preload (also called clamping force or initial tension) is the tensile force induced in a bolt during tightening. It creates the clamping force that holds the joint together and is essential for joint integrity, preventing loosening and fatigue failure.\"}},\n{\"@type\":\"Question\",\"name\":\"What utilization factor should I use?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Typical utilization factors (\u03b7) are 0.7 to 0.9 of the yield strength. For controlled tightening (torque wrench), 0.7\u20130.75 is common. For precision methods (stretch measurement, hydraulic tensioner), 0.85\u20130.9 can be used. Never exceed 0.9 for static applications.\"}},\n{\"@type\":\"Question\",\"name\":\"How is bolt preload related to torque?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The approximate relationship is T = K \u00d7 d \u00d7 F, where K is the nut factor (typically 0.2 for dry steel, 0.15 for lubricated), d is the nominal bolt diameter, and F is the preload force. This is an approximation with \u00b125% uncertainty.\"}},\n{\"@type\":\"Question\",\"name\":\"Why is preload important in bolted joints?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Preload is critical because it: (1) prevents joint separation under external loads, (2) reduces bolt fatigue by minimizing load fluctuations, (3) creates friction that resists shear loads, (4) prevents bolt loosening from vibration, and (5) provides gasket seating force in sealed joints.\"}},\n{\"@type\":\"Question\",\"name\":\"What happens if bolt preload is too high?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Excessive preload can cause bolt yield or fracture during tightening, thread stripping, gasket crushing, flange distortion, or joint member damage. This is why utilization factors are used to keep preload safely below the yield point.\"}}\n]}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[\n{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},\n{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},\n{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Bolt Preload Calculator\",\"item\":\"https:\/\/vibromera.eu\/calculators\/bolt-preload-calculator\/\"}\n]}\n<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link 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20px;font-size:13px;font-weight:700;color:#fff;background:var(--vc-accent);border-radius:var(--vc-radius);text-decoration:none;white-space:nowrap;transition:background 0.15s;}\n.vc-promo-link:hover{background:var(--vc-accent-hover);}\n.vc-footer{text-align:center;padding:32px 16px;font-size:13px;color:var(--vc-ink-muted);}\n.vc-footer a{color:var(--vc-accent);text-decoration:none;}.vc-footer a:hover{text-decoration:underline;}\n.vc-footer-links{margin-top:8px;font-size:12px;}.vc-footer-links a{margin:0 8px;}\n@media print{.vc-section-body{max-height:none!important;}.vc-faq-a{max-height:none!important;}.vc-results{max-height:none!important;padding:24px!important;}.vc-copy-btn,.vc-section-chevron,.vc-faq-chevron,.vc-presets,.vc-promo{display:none!important;}}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-bolt-preload\">\n\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool<\/p>\n    <h1 class=\"vc-header-title\">Bolt Preload Force Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Calculate the assembly preload force in a metric bolt from utilization factor, yield strength, and tensile stress area. F = \u03b7 \u00d7 Rp \u00d7 As.<\/p>\n    <div class=\"vc-badges\">\n        <span class=\"vc-badge\">ISO 898-1<\/span>\n        <span class=\"vc-badge\">VDI 2230<\/span>\n        <span class=\"vc-badge\">M3 \u2013 M64<\/span>\n    <\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-size\">Bolt Size<\/label>\n                <select class=\"vc-select\" id=\"vc-size\">\n                    <option value=\"M6\" data-d=\"6\" data-as=\"20.1\">M6<\/option>\n                    <option value=\"M8\" data-d=\"8\" data-as=\"36.6\">M8<\/option>\n                    <option value=\"M10\" data-d=\"10\" data-as=\"58.0\" selected>M10<\/option>\n                    <option value=\"M12\" data-d=\"12\" data-as=\"84.3\">M12<\/option>\n                    <option value=\"M14\" data-d=\"14\" data-as=\"115\">M14<\/option>\n                    <option value=\"M16\" data-d=\"16\" data-as=\"157\">M16<\/option>\n                    <option value=\"M18\" data-d=\"18\" data-as=\"192\">M18<\/option>\n                    <option value=\"M20\" data-d=\"20\" data-as=\"245\">M20<\/option>\n                    <option value=\"M22\" data-d=\"22\" data-as=\"303\">M22<\/option>\n                    <option value=\"M24\" data-d=\"24\" data-as=\"353\">M24<\/option>\n                    <option value=\"M27\" data-d=\"27\" data-as=\"459\">M27<\/option>\n                    <option value=\"M30\" data-d=\"30\" data-as=\"561\">M30<\/option>\n                    <option value=\"M36\" data-d=\"36\" data-as=\"817\">M36<\/option>\n                    <option value=\"M42\" data-d=\"42\" data-as=\"1121\">M42<\/option>\n                    <option value=\"M48\" data-d=\"48\" data-as=\"1473\">M48<\/option>\n                    <option value=\"M56\" data-d=\"56\" data-as=\"2030\">M56<\/option>\n                    <option value=\"M64\" data-d=\"64\" data-as=\"2676\">M64<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-class\">Property Class<\/label>\n                <select class=\"vc-select\" id=\"vc-class\">\n                    <option value=\"4.6\" data-rm=\"400\" data-rp=\"240\">4.6 \u2014 Rp 240 MPa<\/option>\n                    <option value=\"5.8\" data-rm=\"520\" data-rp=\"420\">5.8 \u2014 Rp 420 MPa<\/option>\n                    <option value=\"8.8\" data-rm=\"800\" data-rp=\"640\" selected>8.8 \u2014 Rp 640 MPa<\/option>\n                    <option value=\"9.8\" data-rm=\"900\" data-rp=\"720\">9.8 \u2014 Rp 720 MPa<\/option>\n                    <option value=\"10.9\" data-rm=\"1040\" data-rp=\"940\">10.9 \u2014 Rp 940 MPa<\/option>\n                    <option value=\"12.9\" data-rm=\"1220\" data-rp=\"1100\">12.9 \u2014 Rp 1100 MPa<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-eta\">Utilization Factor \u03b7 <span class=\"vc-label-hint\">(%)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-eta\" inputmode=\"decimal\" step=\"1\" min=\"10\" max=\"100\" value=\"70\" placeholder=\"e.g. 70\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-kfactor\">Nut Factor K <span class=\"vc-label-hint\">(for torque est.)<\/span><\/label>\n                <select class=\"vc-select\" id=\"vc-kfactor\">\n                    <option value=\"0.20\" selected>0.20 \u2014 Dry \/ as-received<\/option>\n                    <option value=\"0.18\">0.18 \u2014 Lightly oiled<\/option>\n                    <option value=\"0.15\">0.15 \u2014 MoS\u2082 or wax<\/option>\n                    <option value=\"0.12\">0.12 \u2014 Anti-seize paste<\/option>\n                    <option value=\"0.10\">0.10 \u2014 Cadmium plated<\/option>\n                <\/select>\n            <\/div>\n        <\/div>\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-size=\"M10\" data-cls=\"8.8\" data-eta=\"70\">M10 \u00d7 8.8 @ 70%<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-size=\"M16\" data-cls=\"10.9\" data-eta=\"75\">M16 \u00d7 10.9 @ 75%<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-size=\"M20\" data-cls=\"8.8\" data-eta=\"70\">M20 \u00d7 8.8 @ 70%<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-size=\"M24\" data-cls=\"10.9\" data-eta=\"80\">M24 \u00d7 10.9 @ 80%<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">\n                <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\n            <\/button>\n        <\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\">\n                <div class=\"vc-rcard-label\">Assembly Preload Force (F)<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-preload\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Estimated Tightening Torque<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-torque\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Yield Load (100%)<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-yield\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Tensile Stress Area<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-as\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Utilization<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-eta\">\u2014<\/div>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\">\n        <span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Formulas<\/span><\/span>\n        <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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner vc-theory\">\n            <h3>Preload Force<\/h3>\n            <p>The assembly preload force is the target bolt tension during tightening:<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n            <ul>\n                <li><strong>\u03b7<\/strong> \u2014 utilization factor (0.7\u20130.9 typical)<\/li>\n                <li><strong>R<sub>p<\/sub><\/strong> \u2014 proof \/ yield strength (MPa)<\/li>\n                <li><strong>A<sub>s<\/sub><\/strong> \u2014 tensile stress area (mm\u00b2)<\/li>\n            <\/ul>\n            <h3>Torque Estimation<\/h3>\n            <p>Approximate tightening torque (short-form equation):<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n            <ul>\n                <li><strong>K<\/strong> \u2014 nut factor (friction-dependent, typically 0.15\u20130.20)<\/li>\n                <li><strong>d<\/strong> \u2014 nominal bolt diameter (mm)<\/li>\n            <\/ul>\n            <h3>Practical Example<\/h3>\n            <div class=\"vc-example-box\">\n                <div class=\"vc-example-title\">Example \u2014 M10 \u00d7 8.8 @ 70%<\/div>\n                <p><strong>Given:<\/strong> M10, class 8.8 (Rp = 640 MPa), As = 58.0 mm\u00b2, \u03b7 = 70%<\/p>\n                <p>F = 0.70 \u00d7 640 \u00d7 58.0 = <strong>25,984 N \u2248 26.0 kN<\/strong><\/p>\n                <p>T = 0.20 \u00d7 10 \u00d7 25,984 \/ 1000 = <strong>52.0 N\u00b7m<\/strong><\/p>\n            <\/div>\n            <div class=\"vc-warning-box\">\n                <p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Note:<\/strong> Torque-based tightening has \u00b125% uncertainty. For critical joints, use stretch measurement or hydraulic tensioning for greater accuracy.<\/p>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udd17<\/span><span class=\"vc-section-title\">Related Calculators<\/span><\/span>\n        <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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-related\">\n                <a class=\"vc-related-link\" href=\"\/calculators\/bolt-strength-calculator\/\">Bolt Strength Calculator<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/flange-bolt-calculator\/\">Flange Bolt Calculator<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/stud-bolt-torque\/\">Stud Bolt Torque<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/hydraulic-wrench-torque\/\">Hydraulic Wrench Torque<\/a>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span>\n        <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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-promo\">\n    <div class=\"vc-promo-text\"><strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>Professional field balancing instruments and software. Used in 50+ countries.<\/div>\n    <a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a>\n<\/div>\n\n<footer class=\"vc-footer\">\n    <p>\u00a9 2024\u20132026 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p>\n    <p style=\"font-size:12px;margin-top:4px;\">Based on ISO 898-1 \/ VDI 2230. Last updated: February 2026<\/p>\n    <div class=\"vc-footer-links\"><a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a><a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a><\/div>\n<\/footer>\n<\/div>\n\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function(){\n    'use strict';\n    var SLUG='bolt-preload-calculator';\n    function $(id){return document.getElementById(id);}\n    function fmt(n,d){if(isNaN(n)||!isFinite(n))return '\u2014';var f=n.toFixed(d===undefined?2:d);return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'');}\n\n    function calculate(){\n        var sOpt=$('vc-size').selectedOptions[0];\n        var cOpt=$('vc-class').selectedOptions[0];\n        var As=parseFloat(sOpt.getAttribute('data-as'));\n        var d=parseFloat(sOpt.getAttribute('data-d'));\n        var Rp=parseFloat(cOpt.getAttribute('data-rp'));\n        var eta=parseFloat($('vc-eta').value)\/100;\n        var K=parseFloat($('vc-kfactor').value);\n        if(!eta||eta<=0||eta>1){$('vc-results').classList.remove('vc-visible');return;}\n        var F=eta*Rp*As; \/\/ N\n        var Fy=Rp*As;\n        var T=K*d*F\/1000; \/\/ N\u00b7m\n        $('vc-r-preload').innerHTML=fmt(F\/1000,1)+' <span class=\"vc-rcard-unit\">kN<\/span> <span class=\"vc-rcard-unit\">('+fmt(F,0)+' N)<\/span>';\n        $('vc-r-torque').innerHTML=fmt(T,1)+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';\n        $('vc-r-yield').innerHTML=fmt(Fy\/1000,1)+' <span class=\"vc-rcard-unit\">kN<\/span>';\n        $('vc-r-as').innerHTML=fmt(As,1)+' <span class=\"vc-rcard-unit\">mm\u00b2<\/span>';\n        $('vc-r-eta').innerHTML=fmt(eta*100,0)+' <span class=\"vc-rcard-unit\">%<\/span>';\n        $('vc-results').classList.add('vc-visible');\n        saveHistory({size:sOpt.value,class:cOpt.value,eta:$('vc-eta').value,_summary:sOpt.value+' '+cOpt.value+' \u03b7='+$('vc-eta').value+'%'});\n    }\n\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn){\n        btn.addEventListener('click',function(e){e.preventDefault();$('vc-size').value=this.getAttribute('data-size');$('vc-class').value=this.getAttribute('data-cls');$('vc-eta').value=this.getAttribute('data-eta');calculate();});\n    });\n    $('vc-form').addEventListener('input',calculate);\n    $('vc-form').addEventListener('change',calculate);\n\n    $('vc-copy-btn').addEventListener('click',function(){\n        var text='Bolt Preload Calculation\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nBolt: '+$('vc-size').value+', Class: '+$('vc-class').value+'\\nUtilization: '+$('vc-eta').value+'%\\nPreload: '+$('vc-r-preload').textContent+'\\nTorque: '+$('vc-r-torque').textContent+'\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nvibromera.eu';\n        if(navigator.clipboard){navigator.clipboard.writeText(text).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);});}\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn){btn.addEventListener('click',function(){var s=this.closest('.vc-section');s.classList.toggle('vc-open');this.setAttribute('aria-expanded',s.classList.contains('vc-open'));});});\n\n    var faqData=[\n        {q:'What is bolt preload force?',a:'<p>Bolt preload is the tensile force induced in a bolt during tightening. It creates the clamping force that holds the joint together and is essential for joint integrity, preventing loosening and fatigue failure.<\/p>'},\n        {q:'What utilization factor should I use?',a:'<p>Typical values: 0.7 for torque wrench tightening, 0.75 for calibrated torque, 0.85\u20130.9 for hydraulic tensioning or stretch measurement. Never exceed 0.9 for static applications.<\/p>'},\n        {q:'How is bolt preload related to torque?',a:'<p>The approximate relation is T = K \u00d7 d \u00d7 F, where K is the nut factor (typically 0.20 for dry steel). This has \u00b125% uncertainty because ~90% of applied torque is consumed by friction.<\/p>'},\n        {q:'Why is preload important in bolted joints?',a:'<p>Preload prevents joint separation, reduces bolt fatigue, creates friction to resist shear, prevents loosening from vibration, and provides gasket seating force in sealed joints.<\/p>'},\n        {q:'What happens if bolt preload is too high?',a:'<p>Excessive preload can cause bolt yield\/fracture, thread stripping, gasket crushing, flange distortion, or joint member damage. Utilization factors keep preload safely below yield.<\/p>'}\n    ];\n    var fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<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>';});\n    fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(b)b.closest('.vc-faq-item').classList.toggle('vc-open');});\n\n    function saveHistory(entry){var key='vc_history_'+SLUG;var arr=[];try{arr=JSON.parse(localStorage.getItem(key))||[];}catch(e){}entry._ts=new Date().toISOString();arr.unshift(entry);if(arr.length>10)arr=arr.slice(0,10);try{localStorage.setItem(key,JSON.stringify(arr));}catch(e){}}\n\n    function renderFormulas(){try{\n        katex.render('F = \\\\eta \\\\times R_p \\\\times A_s \\\\quad [\\\\text{N}]',$('vc-katex-1'),{displayMode:true,throwOnError:false});\n        katex.render('T = K \\\\times d \\\\times F \\\\quad [\\\\text{N\u00b7mm}]',$('vc-katex-2'),{displayMode:true,throwOnError:false});\n    }catch(e){}}\n\n    function init(){renderFormulas();calculate();}\n    if(document.readyState==='loading'){document.addEventListener('DOMContentLoaded',init);}else{init();}\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>\u09ac\u09cb\u09b2\u09cd\u099f \u09aa\u09cd\u09b0\u09bf\u09b2\u09cb\u09a1 \u09ab\u09cb\u09b0\u09cd\u09b8\u09c7\u09b0 \u099c\u09a8\u09cd\u09af \u09ac\u09bf\u09a8\u09be\u09ae\u09c2\u09b2\u09cd\u09af\u09c7 \u0985\u09a8\u09b2\u09be\u0987\u09a8 \u0995\u09cd\u09af\u09be\u09b2\u0995\u09c1\u09b2\u09c7\u099f\u09b0\u0964 \u09ac\u09cb\u09b2\u09cd\u099f \u09b8\u09be\u0987\u099c, \u09aa\u09cd\u09b0\u09aa\u09be\u09b0\u09cd\u099f\u09bf \u0995\u09cd\u09b2\u09be\u09b8 \u098f\u09ac\u0982 \u0987\u0989\u099f\u09bf\u09b2\u09be\u0987\u099c\u09c7\u09b6\u09a8 \u09ab\u09cd\u09af\u09be\u0995\u09cd\u099f\u09b0 \u09aa\u09cd\u09b0\u09ac\u09c7\u09b6 \u0995\u09b0\u09c1\u09a8 \u098f\u09ac\u0982 \u0985\u09cd\u09af\u09be\u09b8\u09c7\u09ae\u09cd\u09ac\u09b2\u09bf \u09aa\u09cd\u09b0\u09bf\u09b2\u09cb\u09a1 F = \u03b7 \u00d7 Rp \u00d7 As \u0997\u09a3\u09a8\u09be \u0995\u09b0\u09c1\u09a8\u0964<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100040","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100040","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":1,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100040\/revisions"}],"predecessor-version":[{"id":100351,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100040\/revisions\/100351"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=100040"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=100040"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=100040"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}