{"id":2371,"date":"2026-06-25T05:53:53","date_gmt":"2026-06-25T05:53:53","guid":{"rendered":"https:\/\/helicalcutgears.top\/?p=2371"},"modified":"2026-06-25T05:53:53","modified_gmt":"2026-06-25T05:53:53","slug":"helical-gear-standard-sizes-module-reference","status":"publish","type":"post","link":"https:\/\/helicalcutgears.top\/zh\/helical-gear-standard-sizes-module-reference\/","title":{"rendered":"\u87ba\u65cb\u9f7f\u8f6e\u6807\u51c6\u5c3a\u5bf8 \u2014 ISO\u6a21\u6570\u7cfb\u5217\u3001\u8282\u5706\u76f4\u5f84\u548c\u9f7f\u5bbd\u53c2\u8003"},"content":{"rendered":"
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\u87ba\u65cb\u9f7f\u8f6e\u6807\u51c6\u5c3a\u5bf8 \u2014 ISO\u6a21\u6570\u7cfb\u5217\u3001\u8282\u5706\u76f4\u5f84\u548c\u9f7f\u5bbd\u53c2\u8003<\/h1>\n

Selecting the correct module for a helical gear is the first sizing decision \u2014 and the one that determines all subsequent dimensions. This reference guide covers the ISO 54 preferred number series that standardises module values worldwide, how to calculate pitch diameter from module and tooth count at any helix angle, and the face width guidelines that ensure adequate overlap contact ratio for the full noise and load capacity benefit of helical gearing.<\/p>\n

Confirm Your Helical Gear Size \u2192<\/a><\/p>\n<\/div>\n<\/div>\n

The ISO 54 Preferred Number Series for Helical Gear Modules<\/h2>\n

Module Mn in a \u87ba\u65cb\u9f7f\u8f6e<\/strong> is standardised by ISO 54 into two series of preferred numbers. Using a preferred module ensures that standard hobs, grinding wheels, and inspection arbors are available for production \u2014 specifying a non-standard module (e.g. Mn = 3.7) requires custom tooling that adds lead time and cost. The ISO 54 series:<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
First Choice (mandatory for new designs)<\/th>\nSecond Choice (only when first choice does not work)<\/th>\n<\/tr>\n
\u6a21\u5757<\/th>\nTypical Application Range<\/th>\n\u6a21\u5757<\/th>\nWhere Second Choice Is Used<\/th>\n<\/tr>\n<\/thead>\n
M1<\/td>\nInstruments, precision mechanisms<\/td>\nM1.125<\/td>\nRarely; non-standard tooling required<\/td>\n<\/tr>\n
M1.25<\/td>\nSmall mechanism drives, electronics<\/td>\nM1.375<\/td>\nSpace constraints only<\/td>\n<\/tr>\n
M1.5<\/td>\nPrecision instruments, fine mechanism<\/td>\nM1.75<\/td>\nCentre distance constraints<\/td>\n<\/tr>\n
M2<\/td>\nLight automation, food machine, servo<\/td>\nM2.25<\/td>\nReplacement of imperial 10 DP gears<\/td>\n<\/tr>\n
M2.5<\/td>\nLight industrial, small gearboxes<\/td>\nM2.75<\/td>\nSpace constraints<\/td>\n<\/tr>\n
M3<\/td>\nGeneral light industrial, packaging<\/td>\nM3.5<\/td>\n\u2014<\/td>\n<\/tr>\n
M4<\/td>\nGeneral industrial, medium servo<\/td>\nM4.5<\/td>\n\u2014<\/td>\n<\/tr>\n
M5<\/td>\nStandard industrial \u2014 the most common module for enclosed gearboxes<\/td>\nM5.5<\/td>\n\u2014<\/td>\n<\/tr>\n
M6<\/td>\nMedium industrial, pump and fan drives<\/td>\nM7<\/td>\n\u2014<\/td>\n<\/tr>\n
M8<\/td>\nHeavy industrial, crane, conveyor<\/td>\nM9<\/td>\n\u2014<\/td>\n<\/tr>\n
M10<\/td>\nHeavy industrial, rolling mill auxiliaries<\/td>\nM11<\/td>\n\u2014<\/td>\n<\/tr>\n
M12<\/td>\nLarge industrial, marine enclosed gearboxes<\/td>\nM14<\/td>\n\u2014<\/td>\n<\/tr>\n
M16<\/td>\nHeavy-duty drives, kiln enclosed stages<\/td>\nM18<\/td>\n\u2014<\/td>\n<\/tr>\n
M20<\/td>\nVery heavy duty, cement mill pinions<\/td>\nM22<\/td>\n\u2014<\/td>\n<\/tr>\n
M25<\/td>\nLarge open gear drives<\/td>\nM28<\/td>\n\u2014<\/td>\n<\/tr>\n
M32, M40, M50<\/td>\nVery large open gear bull and ring gears<\/td>\nM36, M45<\/td>\n\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Pitch Diameter Reference \u2014 Module \u00d7 Tooth Count at \u03b2 = 20\u00b0<\/h2>\n

\u5bf9\u4e8e \u87ba\u65cb\u9f7f\u8f6e<\/strong> with normal module Mn at helix angle \u03b2 = 20\u00b0, pitch diameter d = Mn \u00d7 z \/ cos 20\u00b0 = Mn \u00d7 z \/ 0.9397 = Mn \u00d7 z \u00d7 1.064. The table below covers the most common module and tooth count combinations:<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
z (teeth)<\/th>\nM3 d (mm)<\/th>\nM4 d (mm)<\/th>\nM5 d (mm)<\/th>\nM6 d (mm)<\/th>\nM8 d (mm)<\/th>\nM10 d (mm)<\/th>\n<\/tr>\n<\/thead>\n
18<\/td>\n57.5<\/td>\n76.7<\/td>\n95.9<\/td>\n115.0<\/td>\n153.4<\/td>\n191.7<\/td>\n<\/tr>\n
20<\/td>\n63.9<\/td>\n85.2<\/td>\n106.5<\/td>\n127.8<\/td>\n170.3<\/td>\n212.9<\/td>\n<\/tr>\n
24<\/td>\n76.7<\/td>\n102.2<\/td>\n127.8<\/td>\n153.3<\/td>\n204.4<\/td>\n255.5<\/td>\n<\/tr>\n
30<\/td>\n95.9<\/td>\n127.8<\/td>\n159.8<\/td>\n191.7<\/td>\n255.5<\/td>\n319.4<\/td>\n<\/tr>\n
36<\/td>\n115.0<\/td>\n153.4<\/td>\n191.7<\/td>\n230.0<\/td>\n306.7<\/td>\n383.4<\/td>\n<\/tr>\n
48<\/td>\n153.4<\/td>\n204.4<\/td>\n255.5<\/td>\n306.7<\/td>\n409.0<\/td>\n511.0<\/td>\n<\/tr>\n
60<\/td>\n191.7<\/td>\n255.5<\/td>\n319.4<\/td>\n383.4<\/td>\n511.0<\/td>\n638.8<\/td>\n<\/tr>\n
80<\/td>\n255.5<\/td>\n340.7<\/td>\n425.9<\/td>\n511.0<\/td>\n681.4<\/td>\n851.7<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

d = Mn \u00d7 z \/ cos \u03b2 at \u03b2 = 20\u00b0. All values in mm.<\/p>\n

Face Width Guidelines \u2014 b\/d and b\/Mn Rules<\/h2>\n

The face width b of a \u87ba\u65cb\u9f7f\u8f6e<\/strong> must satisfy two independent requirements: (1) it must provide adequate overlap contact ratio \u03b5_\u03b2 for the full noise and load capacity benefit of the helical form; (2) it must not exceed the practical ratio b\/d\u2081 that shaft deflection and gear body stiffness can support without unacceptable edge loading.<\/p>\n

\n\n\n\n\n\n\n\n\n
Rule<\/th>\n\u516c\u5f0f<\/th>\n\u5178\u578b\u8303\u56f4<\/th>\nWhy This Limit<\/th>\n<\/tr>\n<\/thead>\n
Minimum face width for \u03b5_\u03b2 \u2265 1<\/td>\nb_min = \u03c0 \u00d7 Mn \/ sin \u03b2<\/td>\nAt \u03b2=20\u00b0: b_min \u2248 9.2 \u00d7 Mn<\/td>\nBelow this, \u03b5_\u03b2 < 1 and the full helical advantage is not realised<\/td>\n<\/tr>\n
Recommended face width<\/td>\nb = 10\u201315 \u00d7 Mn<\/td>\n\u03b5_\u03b2 = 1.1\u20131.6 at \u03b2=20\u00b0<\/td>\nComfortable margin above \u03b5_\u03b2 = 1; practical for most gearbox proportions<\/td>\n<\/tr>\n
Maximum b\/d\u2081 ratio<\/td>\nb \u2264 1.5 \u00d7 d\u2081 (soft flank); b \u2264 1.1 \u00d7 d\u2081 (hard flank)<\/td>\nb\/d\u2081 = 0.5\u20131.0 typical<\/td>\nAbove this, shaft deflection and gear body twist cause severe edge loading even with crowning<\/td>\n<\/tr>\n
Maximum face width for standard housing<\/td>\nb \u2264 0.6 \u00d7 a (centre distance) typically<\/td>\nSet by housing width and shaft bearing span<\/td>\nWider face width requires longer shaft span with proportionally more shaft deflection<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Example: M5, z\u2081=24, \u03b2=20\u00b0 \u2192 d\u2081 = 127.8 mm
\nb_min (\u03b5_\u03b2 \u2265 1) = \u03c0 \u00d7 5 \/ sin 20\u00b0 = 46.1 mm
\nRecommended b = 12 \u00d7 Mn = 60 mm (\u03b5_\u03b2 = 1.30)
\nMax b = 1.1 \u00d7 d\u2081 = 140.6 mm (hard flank, with crowning)
\nPractical standard: b = 60\u201380 mm for this gear<\/p>\n

Standard Bore Diameter Guidelines for Helical Gear Blanks<\/h2>\n

The bore diameter of a \u87ba\u65cb\u9f7f\u8f6e<\/strong> is determined by the transmitted torque and the shaft material strength. A practical starting point for steel shafts transmitting the full rated torque:<\/p>\n

d_bore_min \u2248 4.5 \u00d7 \u221bT \u00a0\u00a0[mm, where T is in N\u00b7m, for standard alloy steel shaft]<\/p>\n

The bore must also be large enough to maintain adequate wall thickness between bore and root circle of the gear teeth. Korea Ever-Power requires a minimum wall thickness of 2.5 \u00d7 Mn between the bore and the root circle for structural integrity \u2014 ensuring the gear blank does not crack at the root-to-bore junction during heat treatment or under service loading. The bore tolerance for keyed connections is H7; for interference-fit connections, H7 or H6 depending on the required fit.<\/p>\n

Korea Ever-Power Supply Range \u2014 M1 to M50<\/h2>\n

\"Korea<\/p>\n

Korea Ever-Power’s production range covers Mn = M1 to M50, OD 20 mm to 2500 mm \u2014 from fine-pitch instrument \u87ba\u65cb\u9f7f\u8f6e<\/strong> to large-module open drive components. All sizes use ISO 54 preferred modules as standard; non-standard modules accepted with custom tooling lead time.<\/p>\n

\u97e9\u56fd\u6c38\u52a8\u529b\u5236\u9020 \u659c\u9f7f\u8f6e<\/a> from Mn = M1 through M50, OD 20\u20132500 mm, DIN Class 3\u20139, in all standard materials from 45# QT through 17CrNiMo6 carburized and SS316L stainless. All modules from the ISO 54 first-choice series are standard production items with available tooling; second-choice modules and non-standard modules (e.g. converted imperial DP sizes) are available with a tooling lead time of 2\u20134 weeks. As a direct \u87ba\u65cb\u9f7f\u8f6e\u5236\u9020\u5546<\/a>, Korea Ever-Power holds master hobs and grinding dressing profiles for all first-choice ISO 54 modules from M1 to M32 on permanent tooling stock.<\/p>\n

\"\u87ba\u65cb\u9f7f\u8f6e\u7684\u5e94\u7528<\/p>\n

\u5e38\u89c1\u95ee\u9898\u89e3\u7b54<\/h2>\n
What is the relationship between diametral pitch (DP) used in the USA and module used internationally?<\/strong><\/p>\n

Module Mn and diametral pitch DP (US\/imperial) are inversely proportional: Mn = 25.4 \/ DP. Common equivalents: DP 8 = Mn 3.175 (close to M3); DP 6 = Mn 4.233 (close to M4); DP 5 = Mn 5.08 (close to M5); DP 4 = Mn 6.35 (close to M6); DP 3 = Mn 8.47 (close to M8). For replacement \u87ba\u65cb\u9f7f\u8f6e<\/strong> from US-designed machinery, Korea Ever-Power can produce to the exact imperial DP module (e.g. DP 6 exactly, not M4.233 rounded) using custom tooling, or can produce the nearest standard ISO module (M4) with a small centre distance or profile shift adjustment. Korea Ever-Power confirms which approach is correct after reviewing the housing centre distance and mating gear specification.<\/p>\n<\/div>\n

Why must the face width exceed 9.2 \u00d7 Mn at \u03b2 = 20\u00b0 for full helical gear performance?<\/strong><\/p>\n

The overlap contact ratio \u03b5_\u03b2 = b \u00d7 sin \u03b2 \/ (\u03c0 \u00d7 Mn) must be \u2265 1.0 for the full helical advantage to be realised \u2014 meaning at least one additional full tooth pitch is simultaneously in contact at all times. Solving for b_min at \u03b5_\u03b2 = 1.0: b_min = \u03c0 \u00d7 Mn \/ sin \u03b2. At \u03b2 = 20\u00b0: b_min = \u03c0 \u00d7 Mn \/ 0.342 = 9.19 \u00d7 Mn. Below this face width, there are instants in the mesh cycle when a single tooth pair carries the full transmitted load \u2014 the same condition as a spur gear. All the noise and load capacity benefits of the helical form depend on \u03b5_\u03b2 \u2265 1. This is the most frequently violated face width rule in preliminary gear designs where the face width is set by packaging constraints without checking \u03b5_\u03b2.<\/p>\n<\/div>\n

Is there a maximum module for hobbing and grinding on standard CNC gear machines?<\/strong><\/p>\n

Standard CNC gear hobbing machines handle Mn = M1\u2013M50+ without a fundamental limitation \u2014 the hob dimensions and machine power scale with module. CNC gear grinding (H\u00d6FLER-type generating grinding) is practically limited to approximately Mn = M32\u2013M40 by grinding wheel size and profile stiffness; very large modules (M40\u2013M50) are typically finish-ground using single-point grinding or profile milling rather than generating grinding. Korea Ever-Power’s in-house grinding capability covers Mn = M1 to M36 in generating grinding and M36 to M50 in form grinding, covering the full module range for enclosed gearbox \u87ba\u65cb\u9f7f\u8f6e<\/strong>.<\/p>\n<\/div>\n

When is a non-standard module necessary, and how does Korea Ever-Power handle it?<\/strong><\/p>\n

Non-standard modules are necessary in two situations: (1) replacement of an existing \u87ba\u65cb\u9f7f\u8f6e<\/strong> that was originally designed to an imperial DP (common in US and UK machinery), or to a non-ISO module specification from older equipment; (2) a very specific centre distance constraint that cannot be met with standard modules and profile shift. Korea Ever-Power handles non-standard modules by producing a custom hob (2\u20134 week additional lead time and tooling cost of 800\u20133000 USD depending on module) or by using profile shift on the nearest standard module to achieve the required centre distance. For the second option, Korea Ever-Power calculates the required profile shift coefficient and confirms that tooth undercut and tip narrowing remain within acceptable limits.<\/p>\n<\/div>\n

\n

Confirm Your Helical Gear Module and Size<\/h2>\n

Provide your power, speed, centre distance, and ratio. Korea Ever-Power selects the correct ISO 54 module, calculates pitch diameter and face width, checks \u03b5_\u03b2 \u2265 1 compliance, and confirms tooling availability \u2014 at the quotation stage before any production commitment.<\/p>\n

Request Module Selection Support<\/a>
\n\u87ba\u65cb\u9f7f\u8f6e\u4ea7\u54c1\u7cfb\u5217<\/a><\/div>\n

M1\u2013M50 \u00b7 ISO 54 preferred series \u00b7 \u03b5_\u03b2 verification \u00b7 Face width calculation \u00b7 DP-to-module conversion \u00b7 MOQ 1 piece<\/p>\n<\/div>\n

\u7f16\u8f91\uff1aCxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Helical Gear Standard Sizes \u2014 ISO Module Series, Pitch Diameter and Face Width Reference Selecting the correct module for a helical gear is the first sizing decision \u2014 and the one that determines all subsequent dimensions. This reference guide covers the ISO 54 preferred number series that standardises module values worldwide, how to calculate pitch […]<\/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-2371","post","type-post","status-publish","format-standard","hentry","category-helical-gears"],"_links":{"self":[{"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/posts\/2371","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/comments?post=2371"}],"version-history":[{"count":2,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/posts\/2371\/revisions"}],"predecessor-version":[{"id":2375,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/posts\/2371\/revisions\/2375"}],"wp:attachment":[{"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/media?parent=2371"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/categories?post=2371"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helicalcutgears.top\/zh\/wp-json\/wp\/v2\/tags?post=2371"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}