{"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":"2026-07-11T21:42:10","modified_gmt":"2026-07-11T21:42:10","slug":"bolt-tightening-torque","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/sk\/calculators\/bolt-tightening-torque\/","title":{"rendered":"User-Data Bolt Torque Sensitivity | Empirical K Model"},"content":{"rendered":"\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"User-Data Bolt Torque Sensitivity Calculator\",\"description\":\"Evaluate the empirical nut-factor relation T=KFd using user-supplied target clamp force, nominal diameter and qualified K values. No bolt class, preload or lubrication recommendation is generated.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/bolt-tightening-torque\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"dateModified\":\"2026-07-11\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\r\n\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Is T=KFd an ISO 16047 formula?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. It is an empirical nut-factor model. ISO 16047:2005 plus Amendment 1:2012 specifies torque\/clamp-force test conditions that can provide assembly-specific data.\"}},{\"@type\":\"Question\",\"name\":\"Does this calculator choose preload or K?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. Target clamp force must come from joint design and K from qualified assembly-specific test data or procedure.\"}},{\"@type\":\"Question\",\"name\":\"Does the displayed K range represent tool accuracy?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. It is only sensitivity to user-entered K values. Tool uncertainty and clamp-force scatter require a validated assembly procedure.\"}}]}<\/script>\r\n\r\n\r\n\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Bolt Torque Calculator\",\"item\":\"https:\/\/vibromera.eu\/calculators\/bolt-tightening-torque\/\"}]}<\/script>\r\n\r\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\r\n\r\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\r\n\r\n<link 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This page does not select bolt grade, preload, lubrication or tightening procedure.<\/p><div class=\"vc-badges\"><span class=\"vc-badge\">Empirical K model<\/span><span class=\"vc-badge\">ISO 16047 test context<\/span><span class=\"vc-badge\">Not VDI 2230 design<\/span><\/div><\/header>\r\n    <div class=\"vc-card\"><form class=\"vc-form\" id=\"vc-torque-form\" autocomplete=\"off\"><div class=\"vc-form-grid\"><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-force\">Target clamp force F <span class=\"vc-label-hint\">(kN; from joint design)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-force\" inputmode=\"decimal\" value=\"50\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-diameter\">Nominal diameter d <span class=\"vc-label-hint\">(mm)<\/span><\/label><input class=\"vc-input\" type=\"text\" id=\"vc-diameter\" inputmode=\"decimal\" value=\"12\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-k\">Qualified nominal nut factor K<\/label><input class=\"vc-input\" type=\"text\" id=\"vc-k\" inputmode=\"decimal\" value=\"0.16\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-k-low\">Qualified lower K<\/label><input class=\"vc-input\" type=\"text\" id=\"vc-k-low\" inputmode=\"decimal\" value=\"0.14\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-k-high\">Qualified upper K<\/label><input class=\"vc-input\" type=\"text\" id=\"vc-k-high\" inputmode=\"decimal\" value=\"0.18\"><\/div><\/div><div class=\"vc-warning-box\"><p style=\"margin:0\"><strong>Input responsibility:<\/strong> F must come from complete joint design; K bounds must represent the exact fastener, nut\/tapped hole, coating, lubricant, bearing surface, reuse state and assembly process. Generic surface-condition tables are not a substitute.<\/p><\/div><\/form><div class=\"vc-results vc-visible\" id=\"vc-results\"><div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Empirical torque sensitivity<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">Copy<\/button><\/div><div class=\"vc-result-grid\"><div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Nominal T=KFd<\/div><div class=\"vc-rcard-value\" id=\"vc-r-torque\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Torque at lower K<\/div><div class=\"vc-rcard-value\" id=\"vc-r-low\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Torque at upper K<\/div><div class=\"vc-rcard-value\" id=\"vc-r-high\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">K sensitivity span<\/div><div class=\"vc-rcard-value\" id=\"vc-r-span\">\u2014<\/div><\/div><\/div><\/div><\/div>\r\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\">Model, units and standards boundary<\/span><\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\"><h3>Empirical nut-factor arithmetic<\/h3><div class=\"vc-formula-box\">T [N\u00b7m] = K \u00b7 F [kN] \u00b7 d [mm]<\/div><p>The numerical equality follows because kN\u00b7mm equals N\u00b7m. K is dimensionless. The equation is a compact empirical correlation, not a universal ISO or VDI formula.<\/p><h3>ISO 16047 test context<\/h3><p><a href=\"https:\/\/www.iso.org\/standard\/27788.html\" target=\"_blank\" rel=\"noopener\">ISO 16047:2005<\/a> with <a href=\"https:\/\/www.iso.org\/standard\/61463.html\" target=\"_blank\" rel=\"noopener\">Amendment 1:2012<\/a> specifies conditions for torque\/clamp-force testing of threaded fasteners. It does not justify generic K values for \u201cdry\u201d, oil, PTFE or anti-seize. Use measured data representative of the actual assembly.<\/p><h3>VDI 2230 design boundary<\/h3><p><a href=\"https:\/\/www.vdi.de\/en\/home\/vdi-standards\/details\/vdi-2230-blatt-1-systematische-berechnung-hochbeanspruchter-schraubenverbindungen-zylindrische-einschraubenverbindungen\" target=\"_blank\" rel=\"noopener\">VDI 2230 Part 1:2015<\/a> covers systematic joint design including minimum clamp load, preload changes, assembly preload, torque and strength verification. This five-input sensitivity calculation does not claim VDI conformity.<\/p><div class=\"vc-info-box\"><p><strong>Not modelled:<\/strong> thread\/bearing friction separation, geometry, tightening scatter distribution, torsion during tightening, embedment, relaxation, external loading, fatigue, temperature, gasket behaviour, prevailing torque, sequence or tool calibration.<\/p><\/div><\/div><\/div><\/div>\r\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>\r\n    <footer class=\"vc-footer\"><p>\u00a9 2024\u20132026 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a><\/p><p>Empirical user-data sensitivity only; not an ISO\/VDI torque recommendation. Scientific review: July 2026.<\/p><\/footer>\r\n<\/div>\r\n<script>(function(){'use strict';function $(i){return document.getElementById(i)}function p(raw){var s=String(raw).trim().replace(\/\\s+\/g,'');if(!\/^[+]?(?:\\d+(?:[.,]\\d*)?|[.,]\\d+)$\/.test(s))return NaN;var n=Number(s.replace(',','.'));return Number.isFinite(n)&&n>0?n:NaN}function f(n){return n.toFixed(6).replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}function calc(){var F=p($('vc-force').value),d=p($('vc-diameter').value),K=p($('vc-k').value),lo=p($('vc-k-low').value),hi=p($('vc-k-high').value);if(![F,d,K,lo,hi].every(Number.isFinite)||lo>K||K>hi){$('vc-results').classList.remove('vc-visible');return}var T=K*F*d,L=lo*F*d,H=hi*F*d;$('vc-r-torque').innerHTML=f(T)+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';$('vc-r-low').innerHTML=f(L)+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';$('vc-r-high').innerHTML=f(H)+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';$('vc-r-span').innerHTML=f(H-L)+' <span class=\"vc-rcard-unit\">N\u00b7m<\/span>';$('vc-results').classList.add('vc-visible');var u=new URL(location);u.searchParams.set('clamp_force_kn',F);u.searchParams.set('nominal_diameter_mm',d);u.searchParams.set('nut_factor',K);u.searchParams.set('nut_factor_low',lo);u.searchParams.set('nut_factor_high',hi);history.replaceState(null,'',u.toString())}$('vc-torque-form').addEventListener('input',calc);$('vc-torque-form').addEventListener('change',calc);$('vc-copy-btn').addEventListener('click',function(){var t='Empirical T=KFd sensitivity\\nF='+$('vc-force').value+' kN; d='+$('vc-diameter').value+' mm\\nK='+$('vc-k').value+' ['+$('vc-k-low').value+','+$('vc-k-high').value+']\\nT='+$('vc-r-torque').textContent+'; range '+$('vc-r-low').textContent+' to '+$('vc-r-high').textContent;if(navigator.clipboard)navigator.clipboard.writeText(t)});document.querySelectorAll('.vc-section-toggle').forEach(function(b){b.addEventListener('click',function(){this.closest('.vc-section').classList.toggle('vc-open')})});var fl=$('vc-faq-list'),q=[['Is T=KFd an ISO formula?','No. It is an empirical nut-factor model.'],['Does this choose preload or K?','No. Both must come from qualified design\/test data.'],['Is the K span tool accuracy?','No. It is only sensitivity to entered K values.']];q.forEach(function(v){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\">'+v[0]+'<\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\"><p>'+v[1]+'<\/p><\/div><\/div><\/div>'});fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(b)b.closest('.vc-faq-item').classList.toggle('vc-open')});var z=new URLSearchParams(location.search),m={clamp_force_kn:'vc-force',nominal_diameter_mm:'vc-diameter',nut_factor:'vc-k',nut_factor_low:'vc-k-low',nut_factor_high:'vc-k-high'};Object.keys(m).forEach(function(k){if(z.has(k))$(m[k]).value=z.get(k)});calc()})();<\/script>\r\n","protected":false},"excerpt":{"rendered":"<p>Evaluate T=KFd using user-supplied target clamp force and qualified nut-factor bounds; no automatic grade, preload, lubrication or ISO\/VDI torque recommendation.<\/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\/sk\/wp-json\/wp\/v2\/calculator\/100043","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/calculator\/100043\/revisions"}],"predecessor-version":[{"id":102334,"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/calculator\/100043\/revisions\/102334"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/media?parent=100043"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/categories?post=100043"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/sk\/wp-json\/wp\/v2\/tags?post=100043"}],"curies":[{"name":"pracovn\u00fd list","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}