{"id":2396,"date":"2026-06-26T05:06:01","date_gmt":"2026-06-26T05:06:01","guid":{"rendered":"https:\/\/helicalcutgears.top\/?p=2396"},"modified":"2026-06-26T05:06:01","modified_gmt":"2026-06-26T05:06:01","slug":"helical-gear-selection-guide-7-questions","status":"publish","type":"post","link":"https:\/\/helicalcutgears.top\/bs\/helical-gear-selection-guide-7-questions\/","title":{"rendered":"Vodi\u010d za prethodni odabir spiralnog zup\u010danika \u2014 7 pitanja za odabir pravog zup\u010danika prilikom prvog odabira"},"content":{"rendered":"
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Vodi\u010d za prethodni odabir spiralnog zup\u010danika \u2014 7 pitanja za odabir pravog zup\u010danika prilikom prvog odabira<\/h1>\n

Potpuno spiralni zup\u010danik<\/strong> specification requires seven engineering answers \u2014 in the right order. Answering them out of sequence \u2014 specifying material before the required spiralni zup\u010danik<\/strong> module; setting DIN class before knowing the pitch-line velocity) leads to over-specified expensive gears or under-specified premature failures. This guide walks through the seven questions in their correct dependency sequence, with the decision criteria and typical answers for each, so that a first-time specification produces a correct, cost-effective spiralni zup\u010danik<\/strong> without multiple revision cycles.<\/p>\n

Get Expert Helical Gear Specification \u2192<\/a><\/p>\n<\/div>\n<\/div>\n

Why the Sequence Matters \u2014 Dependencies Between the Seven Questions<\/h2>\n

The seven questions in this guide are not independent \u2014 later questions depend on the answers to earlier ones. The correct dependency chain is: shaft geometry \u2192 power and ratio \u2192 service factor \u2192 module\/size \u2192 environment and material \u2192 accuracy class \u2192 documentation. Skipping steps or working out of sequence produces specifications that are internally inconsistent \u2014 for example, specifying DIN Class 5 for a slow-running M12 gear (unnecessarily expensive) or DIN Class 7 for a 30 m\/s pitch-line velocity gear (unachievable without grinding). Work through the questions in order for every new spiralni zup\u010danik<\/strong> nabavka.<\/p>\n

\n
Prvi kvartal
\nShaft
\ngeometry<\/div>\n
Drugi kvartal
\nPower &
\nratio<\/div>\n
Tre\u0107i kvartal
\nService
\nfactor<\/div>\n
\u010cetvrti kvartal
\nModul
\n& size<\/div>\n
Peto tromjese\u010dje
\nEnviron\u00adment
\n& material<\/div>\n
Q6
\nBuka
\n& DIN<\/div>\n
Q7
\nDocumen\u00adtation<\/div>\n<\/div>\n

Question 1 \u2014 What Is the Shaft Arrangement?<\/h2>\n

Parallel shafts \u2192 confirmed spiralni zup\u010danik<\/strong> application \u2192 spiralni zup\u010danik<\/a> (proceed to Q2).<\/strong> Non-parallel, non-intersecting \u2192 crossed helical or worm gear. Intersecting at 90\u00b0 \u2192 bevel gear. The vast majority of industrial drives use parallel shafts \u2014 the spiralni zup\u010danik<\/strong> the default starting point for any drive specification exercise. If the shaft arrangement is genuinely fixed at 90\u00b0 by machine layout, confirm whether a bevel gear (intersecting shafts) or a worm gear (non-intersecting) is the correct solution before proceeding with the spiralni zup\u010danik<\/strong> selection process.<\/p>\n

Question 2 \u2014 What Are the Power, Speed, and Required Gear Ratio?<\/h2>\n

The three fundamental drive parameters determine the transmitted force magnitude and the pitch-line velocity \u2014 the two quantities that govern all subsequent specification choices:<\/p>\n

Step 2a: Transmitted torque T\u2081 = 9550 \u00d7 P [kW] \/ n\u2081 [RPM] [N\u00b7m]
\nStep 2b: Gear ratio i = z\u2082\/z\u2081 = n\u2081\/n\u2082
\nStep 2c: Tangential force (estimated, before module is known):
\nF_t_est \u2248 2T\u2081 \/ d\u2081_estimate (use d\u2081 \u2248 60\u2013120 mm as first estimate)
\nStep 2d: Pitch-line velocity v_est = \u03c0 \u00d7 d\u2081_est \u00d7 n\u2081 \/ 60,000 [m\/s]<\/p>\n

The pitch-line velocity estimate from Step 2d immediately constrains the DIN accuracy class (Q6) \u2014 if v_est > 15 m\/s, DIN Class 5 grinding will be required regardless of noise requirements. Record this early, as it affects cost before the module is known.<\/p>\n

Question 3 \u2014 What Is the Application Service Factor (KA)?<\/h2>\n

The service factor KA amplifies the transmitted force through the entire specification \u2014 a higher KA requires a larger module, wider face width, or harder material. Determine KA from the AGMA 2101 power source and driven machine classifications (see the dedicated service factor guide, Art49):<\/p>\n

\n\n\n\n\n\n\n\n\n
Application Category<\/th>\nTypical KA Range<\/th>\nKey Driver<\/th>\nGoverning Specification Risk<\/th>\n<\/tr>\n<\/thead>\n
VFD-driven centrifugal pump\/fan (smooth)<\/td>\n1.00\u20131.25<\/td>\nVFD limits start torque; uniform load<\/td>\nEasy to underestimate if DOL motor used instead<\/td>\n<\/tr>\n
Conveyor, compressor, machine tool<\/td>\n1,25\u20131,50<\/td>\nDOL motor start; moderate load variation<\/td>\nVerify motor start method before fixing KA<\/td>\n<\/tr>\n
Mining, crane, heavy press<\/td>\n1.75\u20132.50<\/td>\nShock loading; frequent heavy start<\/td>\nBoth fatigue KA and static peak check required<\/td>\n<\/tr>\n
Rubber mixer, crusher (impact)<\/td>\n2.50\u20134.00<\/td>\nFrozen charge; tramp iron impact<\/td>\nStatic bending check at T_peak governs module<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Question 4 \u2014 What Module and Face Width Are Needed?<\/h2>\n

With T\u2081, KA, and the gear ratio i, the required module Mn can be estimated from the ISO 6336 contact stress formula simplified to a preliminary sizing equation:<\/p>\n

Preliminary module estimate (contact stress governs, carburized 20CrMnTi material, S_H = 1.1):
\nMn_est \u2248 1.5 \u00d7 (T\u2081 \u00d7 KA \u00d7 (i+1) \/ (i \u00d7 b_ratio \u00d7 z\u2081\u00b2 \u00d7 \u03c3_H_lim\u00b2))^(1\/3)
\nwhere b_ratio = b\/d\u2081 \u2248 0.8 (typical industrial)
\nz\u2081 = 20\u201324 (assumed pinion tooth count)
\n\u03c3_H_lim = 1500\u20131600 MPa (carburized)<\/p>\n

Simpler field formula (\u00b130% accuracy):
\nMn_est \u2248 (T\u2081 \u00d7 KA)^0.33 \/ 10 [mm, for T\u2081 in N\u00b7m]<\/p>\n

Examples:
\nT\u2081 = 500 N\u00b7m, KA = 1.25 \u2192 Mn_est \u2248 (625)^0.33 \/ 10 \u2248 8.5\/10 \u2248 0.85 \u2192 try M1 or M1.5 (small drive)
\nT\u2081 = 5,000 N\u00b7m, KA = 1.5 \u2192 Mn_est \u2248 (7500)^0.33 \/ 10 \u2248 19.6\/10 \u2248 2.0 \u2192 try M2\u2013M3
\nT\u2081 = 50,000 N\u00b7m, KA = 2.0 \u2192 Mn_est \u2248 (100,000)^0.33 \/ 10 \u2248 46\/10 \u2248 4.6 \u2192 try M5<\/p>\n

Always round to the nearest ISO 54 preferred module<\/strong> (M1, M1.25, M1.5, M2, M2.5, M3, M4, M5, M6, M8, M10, M12, M16, M20, M25, M32, M40, M50). Non-preferred modules require custom tooling \u2014 add 2\u20134 weeks lead time and 800\u20133,000 USD tooling cost. The preliminary formula gives a starting point; confirm with full ISO 6336-2 and ISO 6336-3 calculation (see Art52) before finalising.<\/div>\n

Question 5 \u2014 What Is the Operating Environment and Required Material?<\/h2>\n

\"helical<\/p>\n

Material selection for a spiralni zup\u010danik<\/strong> is driven by the operating environment as much as by load \u2014 the same module M5 gear may require 20CrMnTi carburized in a standard industrial application, SS316L in a food-processing or chemical environment, or 17CrNiMo6 with Charpy \u221240\u00b0C certification in a cold-climate marine or offshore installation<\/p>\n

\n\n\n\n\n\n\n\n\n\n
Environment<\/th>\nMaterial Requirement<\/th>\n\u03c3_H lim Range<\/th>\nSpecial Considerations<\/th>\n<\/tr>\n<\/thead>\n
Standard industrial (enclosed, clean, ambient)<\/td>\n20CrMnTi carburized (preferred) or 42CrMo QT<\/td>\n490\u20131650 MPa depending on treatment<\/td>\nMaterial tier matched to required \u03c3_H; ISO 6336 MQ grade standard<\/td>\n<\/tr>\n
Food contact or pharmaceutical (wet, hygienic)<\/td>\nSS316L stainless steel, or FDA-grade POM\/PEEK polymer<\/td>\n200\u2013450 MPa (SS316L); 20\u201390 MPa (polymer)<\/td>\nFDA 21 CFR compliance; NSF H1 lubricant; no EP additives near food<\/td>\n<\/tr>\n
Marine or offshore (salt air, intermittent immersion)<\/td>\n17CrNiMo6 carburized; Charpy \u221240\u00b0C certification for cold climates<\/td>\n1600\u20131800 MPa<\/td>\nEN 10204 3.2 material certificate; class society survey (DNV, LR)<\/td>\n<\/tr>\n
Chemical (acid, alkali, solvent exposure)<\/td>\nSS316L or Duplex SS (2205); hard coating on request<\/td>\n180\u2013420 MPa (SS316L)<\/td>\nConfirm chemical compatibility of coating or base material with process fluid<\/td>\n<\/tr>\n
High temperature (>120\u00b0C continuous)<\/td>\nH13 tool steel or 17-4PH stainless for high-temp applications<\/td>\n800\u20131200 MPa at 120\u00b0C<\/td>\nOil viscosity selection critical: VG 220+ synthetic oil at high ambient temperature<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Question 6 \u2014 What Are the Noise, Vibration, and Precision Requirements?<\/h2>\n

The pitch-line velocity from Q2 and the noise\/precision target together determine the DIN accuracy class for the spiralni zup\u010danik<\/strong>:<\/p>\n

\n
Industrial standard (v < 5 m\/s, noise < 80 dB(A))<\/strong><\/p>\n

DIN Class 7\u20138 (as-hobbed) is adequate. No tip relief required. This covers most slow industrial conveyors, mixers, and pump drives. The spiralni zup\u010danik<\/strong> can be left in the as-hobbed condition after heat treatment \u2014 saving the grinding step.<\/p>\n<\/div>\n

General industrial (5\u201315 m\/s, noise < 75 dB(A))<\/strong><\/p>\n

DIN Class 5\u20136 (ground). Tip relief recommended. K_V at 15 m\/s for Class 7 is 1.35\u20131.5 \u2014 marginal for the gear strength calculation. Most enclosed industrial gearboxes with carburized spiralni zup\u010danici<\/strong> fall in this category.<\/p>\n<\/div>\n

High-speed or precision (>15 m\/s, noise < 70 dB(A), or servo)<\/strong><\/p>\n

DIN Class 4\u20135 mandatory. Parabolic tip relief required. At v > 15 m\/s, K_V for Class 7\u20138 exceeds acceptable limits. This covers EV reducers, compressor gearboxes, printing presses, and all high-precision servo spiralni zup\u010danik<\/strong> aplikacije.<\/p>\n<\/div>\n

Ultra-precision (NVH critical, < 60 dB(A), or register-sensitive)<\/strong><\/p>\n

DIN Class 3\u20134 with isotropic superfinishing (Ra \u2264 0.05 \u00b5m). Tip relief and lead crowning both required. Applies to EV final stage (top NVH tier), security printing, aerospace instrument gears. Korea Ever-Power achieves DIN Class 3 with TE < 2 \u00b5m.<\/p>\n<\/div>\n<\/div>\n

Question 7 \u2014 What Documentation and Certification Is Required?<\/h2>\n

Documentation requirements determine the inspection scope and supplier qualification level. Specifying more documentation than is genuinely needed adds cost and lead time; specifying too little creates risk at incoming inspection and installation. The correct documentation scope for each spiralni zup\u010danik<\/strong> application category:<\/p>\n

\n\n\n\n\n\n\n\n\n\n
Primjena<\/th>\nRequired Documentation<\/th>\nCertificate Type<\/th>\n<\/tr>\n<\/thead>\n
Standard industrial replacement<\/td>\nGear analyser report (profile + lead + pitch); hardness survey; dimensional check<\/td>\nEN 10204 2.2 (test report by manufacturer)<\/td>\n<\/tr>\n
Critical industrial or OEM supply<\/td>\nAll above + EN 10204 3.1 material certificate + OES spectrometer + case depth traverse<\/td>\nEN 10204 3.1 (authorised inspector signature)<\/td>\n<\/tr>\n
Marine \/ offshore \/ power generation<\/td>\nAll above + class society 3.2 certificate (DNV, LR, BV, KR) with witness survey<\/td>\nEN 10204 3.2 (independent inspector; class society)<\/td>\n<\/tr>\n
Automotive OEM (EV, passenger vehicle)<\/td>\nIATF 16949 supplier; PPAP Level 3; dimensional CMM report; TE curve from analyser; FMEA<\/td>\nPPAP (production part approval process) per AIAG manual<\/td>\n<\/tr>\n
Food \/ pharmaceutical<\/td>\nFDA 21 CFR material compliance letter + EN 10204 3.1 + NSF H1 lubricant certificate<\/td>\nFDA material compliance; NSF H1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

The Complete 7-Question Specification Summary<\/h2>\n

\"Korea<\/p>\n

Korea Ever-Power’s engineering team reviews every spiralni zup\u010danik<\/strong> order against the seven-question specification checklist before confirming the order \u2014 ensuring that shaft geometry, power, service factor, module, material, DIN class, and documentation are all consistent and complete before production begins<\/p>\n

A correctly completed specification for a spiralni zup\u010danik<\/strong> order to Korea Ever-Power answers all seven questions explicitly:<\/p>\n

Q1 Shaft: Parallel shafts \u2192 helical gear confirmed
\nQ2 Drive: 75 kW, 1500 RPM input, i = 3:1 \u2192 T\u2081 = 477 N\u00b7m, v_est = 10 m\/s
\nQ3 Service: Loaded conveyor, DOL start \u2192 KA = 1.50
\nQ4 Module: Mn_est = (716)^0.33\/10 \u2248 0.89 \u2192 select M2 \u2192 confirm ISO 6336 at M5, z\u2081=24
\nQ5 Material: Standard industrial, no food\/marine \u2192 20CrMnTi carburized HRC 58\u201362
\nQ6 Accuracy: 10 m\/s, noise < 75 dB(A) \u2192 DIN Class 5\u20136, tip relief C_\u03b1 = 12 \u00b5m
\nQ7 Documents: Critical OEM pump drive \u2192 EN 10204 3.1 + gear analyser + hardness survey<\/p>\n

Korea Ever-Power’s engineering review confirms the ISO 6336 strength calculation for both pitting (S_H = 2.8) and bending (S_F = 4.6), and issues the order confirmation with all seven parameters locked before production begins. As a direct proizvo\u0111a\u010d spiralnih zup\u010danika<\/a>, Korea Ever-Power requests the answers to all seven questions at the enquiry stage \u2014 not just module and material. Browse the complete Asortiman proizvoda sa spiralnim zup\u010danicima<\/a> for standard and custom specifications.<\/p>\n

\u010cesto postavljana pitanja<\/h2>\n
What is the single most common helical gear specification error in industrial procurement?<\/strong><\/p>\n

Underestimating the service factor KA for a spiralni zup\u010danik<\/strong> \u2014 particularly treating a DOL motor drive as KA = 1.0 without checking the motor’s starting torque method. A direct-on-line (DOL) started induction motor applies 250\u2013350% of rated torque at each startup. For a drive that starts 5 times per day under moderate load, this gives an effective AGMA “light shock” source classification \u2014 requiring KA \u2265 1.25. Using KA = 1.0 for this drive produces a spiralni zup\u010danik<\/strong> that is undersized by approximately 20\u201330% for the actual loading history, leading to premature pitting or tooth root fatigue at 40\u201360% of the calculated design life. The fix \u2014 confirming the motor starting method and daily start count before fixing KA \u2014 takes 5 minutes and prevents a gear failure.<\/p>\n<\/div>\n

When is it acceptable to use a standard catalogue helical gear rather than a custom specified gear?<\/strong><\/p>\n

A standard catalogue spiralni zup\u010danik<\/strong> (typically DIN Class 7\u20138, QT material, standard module and bore from stock) is acceptable when: Q1\u2013Q6 answers produce a specification that falls within a standard catalogue size; the application is not safety-critical (failure would cause production loss, not injury or environmental damage); the pitch-line velocity is below 5 m\/s; and the service factor is below 1.5. When any of these conditions is not met, a custom-specified spiralni zup\u010danik<\/strong> \u2014 with ISO 6336 calculation, gear analyser verification, and EN 10204 3.1 certificate \u2014 is the correct choice. Korea Ever-Power offers standard stock gears for the first condition and custom production for all others.<\/p>\n<\/div>\n

How long does it take to go from answering the 7 questions to receiving a finished helical gear?<\/strong><\/p>\n

With all seven questions answered at the time of enquiry, Korea Ever-Power’s standard lead times are: DIN Class 7\u20138 QT spiralni zup\u010danik<\/strong> (as-hobbed, no grinding): 2\u20133 weeks. DIN Class 5\u20136 carburized and ground: 4\u20136 weeks. DIN Class 4\u20135 with tip relief, marine documentation: 6\u20138 weeks. PPAP automotive: 10\u201314 weeks (PPAP process in addition to production). These lead times assume complete specification \u2014 questions that require engineering clarification (ambiguous shaft arrangement, missing KA information, unspecified centre distance) each add 1\u20132 weeks. The seven-question spiralni zup\u010danik<\/strong> framework is designed to eliminate these clarification cycles before production starts.<\/p>\n<\/div>\n

Can Korea Ever-Power recommend the answers to the seven questions if only the application type and power are known?<\/strong><\/p>\n

Yes \u2014 this is Korea Ever-Power’s standard pre-sales engineering service. Provide the application type (conveyor, mixer, pump, printing press, EV, etc.), rated power, input speed, and the driven machine (or its output speed\/torque requirements). Korea Ever-Power’s engineering team completes the seven questions using the application-specific standards and field experience data, performs the ISO 6336 strength calculation for the selected module, and returns a complete specification recommendation \u2014 module, material, DIN class, tip relief, documentation scope, and indicative price \u2014 within 2\u20133 business days. This specification recommendation is non-binding and is provided free of charge before any order commitment.<\/p>\n<\/div>\n

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Get Your Helical Gear Specification Reviewed<\/h2>\n

Send Korea Ever-Power your answers to the seven questions for your spiralni zup\u010danik<\/strong> \u2014 or just the application type, power, and speed. Korea Ever-Power’s engineering team completes the specification, performs ISO 6336 calculations, and returns a module, material, DIN class, and documentation recommendation within 2\u20133 business days. Free of charge, no obligation to order.<\/p>\n

Start Free Specification Review<\/a>
\nAsortiman proizvoda sa spiralnim zup\u010danicima<\/a><\/div>\n

7-question framework \u00b7 ISO 6336 calculation \u00b7 Module + DIN class + material recommendation \u00b7 2\u20133 business days \u00b7 No obligation<\/p>\n<\/div>\n

Urednik: Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Helical Gear Pre-Selection Guide \u2014 7 Questions to Specify the Right Gear First Time A complete helical gear specification requires seven engineering answers \u2014 in the right order. Answering them out of sequence \u2014 specifying material before the required helical gear module; setting DIN class before knowing the pitch-line velocity) leads to over-specified expensive gears […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[3082],"tags":[],"class_list":["post-2396","post","type-post","status-publish","format-standard","hentry","category-helical-gears"],"_links":{"self":[{"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/posts\/2396","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/comments?post=2396"}],"version-history":[{"count":2,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/posts\/2396\/revisions"}],"predecessor-version":[{"id":2398,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/posts\/2396\/revisions\/2398"}],"wp:attachment":[{"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/media?parent=2396"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/categories?post=2396"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helicalcutgears.top\/bs\/wp-json\/wp\/v2\/tags?post=2396"}],"curies":[{"name":"radni list","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}