{"id":1593,"date":"2026-07-15T03:49:57","date_gmt":"2026-07-15T03:49:57","guid":{"rendered":"https:\/\/gearrack.top\/product\/involute-internal-gear-42crmo-din-cl-7-per-drawing\/"},"modified":"2026-07-15T03:50:03","modified_gmt":"2026-07-15T03:50:03","slug":"involute-internal-gear-42crmo-din-cl-7-per-drawing","status":"publish","type":"product","link":"https:\/\/gearrack.top\/it\/product\/involute-internal-gear-42crmo-din-cl-7-per-drawing\/","title":{"rendered":"Involute Internal Gear – 42CrMo, DIN Cl.7, Per Drawing"},"content":{"rendered":"
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<\/p>\n

Product Overview<\/h2>\n
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\n \"Involute\n <\/div>\n
\n

Involute internal gears<\/strong> \u2014 also called ring gears or annular gears \u2014 are circular gears in which the teeth are cut on the inner cylindrical surface following a standard involute tooth profile. The gears on the ring gear are internal: the mating external pinion runs inside the ring, with both gears rotating in the same direction. The involute tooth form is the universal standard for precision gears because the involute profile guarantees a constant velocity ratio throughout the mesh cycle regardless of small variations in centre distance \u2014 a property no other tooth form can match. Korea Ever-Power’s involute internal gears in alloy steel and stainless steel to module M4.0 and inner diameter 30 mm serve the most demanding precision applications: planetary gearboxes and automotive drives where the accuracy and load capacity of the ring gear directly determine the system’s performance.<\/p>\n

Korea Ever-Power has focused on CNC machining since 2007. All steps are handled in one location \u2014 CNC machining, turning, and sheet metal fabrication \u2014 making the process speedy, cost-efficient, and well-controlled. Every production order for involute internal gears<\/a> is logged into a computerised system and can be followed closely from order receipt to shipment. MOQ 50 pieces.<\/p>\n<\/p><\/div>\n<\/div>\n

The involute tooth profile has a defining geometric property: the normal to the tooth surface at any contact point always passes through the pitch point \u2014 the point on the line of centres that divides the centre distance in the ratio of the two pitch radii. This property, known as the law of gearing, means that the instantaneous transmission ratio at every contact position throughout the mesh cycle is identical to the ratio of the tooth counts. No other tooth profile provides this constant velocity ratio; the involute is the only profile that guarantees it geometrically, regardless of centre distance variation.<\/p>\n

<\/p>\n

Product Specifications<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Involute Internal Gear \u2014 Product Specification<\/th>\n<\/tr>\n<\/thead>\n
Tooth Form<\/strong><\/td>\nInvolute (standard full-depth)<\/td>\n<\/tr>\n
Material<\/strong><\/td>\nAlloy steel, stainless steel \u2014 customised grades per drawing<\/td>\n<\/tr>\n
Shape<\/strong><\/td>\nRound (annular \/ ring form)<\/td>\n<\/tr>\n
Module<\/strong><\/td>\nMaximum up to M4.0 (metric); inch DP equivalent available<\/td>\n<\/tr>\n
Inner Diameter<\/strong><\/td>\nMaximum 30 mm<\/td>\n<\/tr>\n
Application<\/strong><\/td>\nPlanetary gearboxes, automotive drives<\/td>\n<\/tr>\n
Minimum Order Quantity<\/strong><\/td>\n50 pieces<\/td>\n<\/tr>\n
Quotation Elements<\/strong><\/td>\nProduct drawing (DWG, IGS, STEP, UG, PDF, SolidWorks), material, quantity, surface treatment<\/td>\n<\/tr>\n
Production Equipment<\/strong><\/td>\n30 sets CNC, 15 sets CNC turning, 10 sets sheet metal fabrication \u2014 all in-house<\/td>\n<\/tr>\n
Manufacturing Experience<\/strong><\/td>\nCNC machining focused since 2007<\/td>\n<\/tr>\n
Progress Reporting<\/strong><\/td>\nWeekly digital photo and video reports available without factory visit<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

The Involute Profile \u2014 Why It Is the Universal Standard<\/h2>\n

\"types<\/p>\n

The involute of a circle is the curve traced by the end of a taut string unwinding from a cylinder \u2014 a naturally occurring curve with the unique property that its tangent at every point is perpendicular to the radius drawn from the circle’s centre to that point. When an involute gear tooth meshes with a mating involute tooth, the contact point moves along the line of action (a straight line tangent to both base circles) throughout the mesh cycle. The key consequences for precision gear design:<\/p>\n

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Constant Velocity Ratio<\/h3>\n

The instantaneous angular velocity ratio is constant throughout the mesh cycle \u2014 exactly equal to the inverse ratio of the tooth counts. This is the law of gearing, and the involute profile is the only profile that satisfies it inherently. For a planetary gearbox or automotive transmission where the ring gear’s transmission ratio must be accurate, the involute profile guarantees this accuracy by geometry, not by manufacturing perfection.<\/p>\n<\/p><\/div>\n

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Centre Distance Insensitivity<\/h3>\n

Small variations in the centre distance between the ring gear and its mating pinion (from manufacturing tolerance, thermal expansion, or bearing deflection) do not affect the transmission ratio \u2014 the involute pair maintains the same velocity ratio across a range of centre distances. This makes the involute ring gear tolerant of the dimensional variations that are unavoidable in production gearboxes, where achieving exact theoretical centre distance is not practical.<\/p>\n<\/p><\/div>\n

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Conjugate Action<\/h3>\n

Two mating involute gears act as conjugate pairs \u2014 the shape of one tooth uniquely determines the shape of the mating tooth that produces smooth, constant-ratio transmission. This conjugate property means that any external involute gear (pinion) will mesh correctly with any internal involute ring gear of the same module and pressure angle, provided the interference and minimum tooth count difference conditions are met.<\/p>\n<\/p><\/div>\n

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Interchangeability<\/h3>\n

Involute gears of the same module, pressure angle, and standard (ISO\/DIN\/ANSI\/JIS) are interchangeable regardless of tooth count. A Korea Ever-Power M2 DIN involute internal ring gear will mesh with any M2 DIN external pinion from any manufacturer worldwide. This interchangeability is the industrial standard that makes the involute system the universal gear tooth form \u2014 and it is why Korea Ever-Power’s involute internal gears are specified by designers who need global supply chain flexibility.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Manufacturing and Quality<\/h2>\n

\"Ever-Power<\/p>\n

Korea Ever-Power has focused on CNC machining since 2007, with rich experience in precision internal gear production. The facility handles all steps in one location \u2014 CNC internal gear shaping, CNC turning of the bore and OD, sheet metal fabrication of housings and flanges, heat treatment, and final inspection \u2014 making the process speedy, cost-efficient, and well-controlled without the communication delays of multi-supplier production chains.<\/p>\n

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30 Sets CNC Gear Shaping<\/h3>\n

Internal gear teeth are cut by CNC gear shaping machines using profile-ground form cutters \u2014 the standard process for internal involute gears. The shaping machine’s cutter reciprocates axially while rotating in synchrony with the ring gear blank, generating the involute tooth profile on the inner bore. Korea Ever-Power’s 30-set CNC fleet provides the capacity for both prototype quantities and production batches without scheduling conflicts.<\/p>\n<\/p><\/div>\n

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Computerised Production Tracking<\/h3>\n

The entire production process is logged into a computerised management system. Every step \u2014 from receiving the order, material procurement, CNC setup, gear cutting, heat treatment, inspection, and shipment \u2014 can be tracked in real time. Customers who cannot visit the factory receive weekly digital photo and video reports showing the processing progress. This transparency eliminates uncertainty about delivery schedule.<\/p>\n<\/p><\/div>\n

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QC Department \u2014 Start to Finish<\/h3>\n

Korea Ever-Power’s QC department controls quality from the start of production to the completion of goods. Incoming material inspection, in-process dimensional checks at each CNC operation, post-heat-treatment hardness verification, final gear profile measurement, and visual inspection are all performed in-house. In the event of any quality issue, the QC records allow rapid identification and isolation of the non-conforming production step.<\/p>\n<\/p><\/div>\n

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Quality Non-Conformance Resolution<\/h3>\n

In the rare event of a non-conformance in delivered involute internal gears, Korea Ever-Power will not risk producing inferior products and will rework or re-manufacture to the correct specification. The QC inspection record from the original production batch is the baseline for root-cause analysis. The cost of re-manufacture and re-shipment for confirmed quality non-conformances is borne by Korea Ever-Power.<\/p>\n<\/p><\/div>\n<\/div>\n

\"measuring<\/p>\n

<\/p>\n

Applications<\/h2>\n
\n
\n
\u2699\ufe0f<\/div>\n

Planetary Gearboxes<\/h3>\n

Alloy steel involute internal ring gears M2\u2013M4 as the fixed annulus in servo planetary gearboxes, robot joint planetary reducers, and industrial servo drive planetary stages. The involute tooth form’s centre-distance insensitivity is particularly valuable in planetary stages where the ring gear bore must accommodate the planet gear bearing tolerance stack.<\/p>\n<\/p><\/div>\n

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<\/div>\n

Automotive Drives<\/h3>\n

Alloy or stainless involute internal ring gears M1\u2013M3 in automatic transmission planetary stages, EV motor planetary reduction drives, and seat adjustment mechanism planetary gear sets. The standard involute form ensures interchangeability with OEM planet and sun gears from any standard source.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Medical Instrument Drives<\/h3>\n

Stainless steel involute internal gears M0.5\u2013M2, ID \u2264 30 mm in surgical tool planetary drives and infusion pump planetary stages. Stainless material meets the corrosion resistance and sterilisation compatibility requirements; involute profile meets the transmission ratio accuracy requirement at the inner diameter and module range.<\/p>\n<\/p><\/div>\n

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<\/div>\n

Electric Screwdrivers and Power Tools<\/h3>\n

Alloy steel or POM involute internal ring gears M1\u2013M2 in electric screwdriver planetary torque limiters, cordless drill planetary speed reduction stages, and rotary tool planetary drives. The compact inner diameter (\u2264 30 mm) suits the small-body power tool housing envelope.<\/p>\n<\/p><\/div>\n

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<\/div>\n

Bicycle Components<\/h3>\n

Stainless or alloy involute internal ring gears M1\u2013M2 in internally geared bicycle hub transmission planetary stages (e.g. Shimano Nexus equivalent designs) and e-bike mid-drive planetary reduction gear sets. Small OD, precise involute profile, and high material efficiency suit the compact bicycle hub envelope.<\/p>\n<\/p><\/div>\n

\n
\u26fd<\/div>\n

Pumps and Positioning Equipment<\/h3>\n

Involute internal ring gears in gear pump internal rotors (gerotor pump ring gear), positioning equipment planetary drives, and fluid metering system drives. The involute gerotor ring gear’s inner tooth profile is the critical accuracy element determining the pump’s volumetric efficiency and flow uniformity.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Frequently Asked Questions<\/h2>\n
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Is Korea Ever-Power a trading company or a manufacturer?<\/p>\n

Korea Ever-Power is a manufacturer. All machining steps \u2014 CNC internal gear shaping, CNC turning, sheet metal fabrication, heat treatment, and final inspection \u2014 are handled in one location. This integrated single-facility production makes the process speedy, cost-efficient, and quality-controlled, eliminating the communication delays and quality handoff risks of multi-supplier production chains. The facility has focused on CNC machining since 2007.<\/p>\n<\/div>\n

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What information is needed for a quotation?<\/p>\n

Korea Ever-Power needs four elements to provide an accurate quotation: the product drawing (DWG, IGS, STEP, UG, PDF, or SolidWorks format preferred), the material specification, the required quantity, and the surface treatment requirement. If no drawing is available, Korea Ever-Power can design the involute internal ring gear from the application requirements \u2014 provide the required module, inner diameter, tooth count, material preference, and operating conditions, and the design team will produce a drawing for approval.<\/p>\n<\/div>\n

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Can I understand production progress without visiting the factory?<\/p>\n

Yes \u2014 Korea Ever-Power provides a detailed production plan at the start of the order and sends weekly reports with digital pictures and videos showing the processing progress at each stage. The computerised production management system logs every step from order receipt through shipment. Customers who cannot make a factory visit receive the same production visibility as those who can. If a specific production milestone needs confirmation (e.g. heat treatment completion, final inspection pass), Korea Ever-Power will provide the relevant documentation or photo evidence.<\/p>\n<\/div>\n

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\n

What is the internal gear tooth cutting process and why does the ID limit matter?<\/p>\n

Internal involute gear teeth are cut by CNC gear shaping \u2014 a form cutter reciprocates axially inside the ring gear bore while synchronously rotating with the workpiece to generate the involute tooth profile. The minimum inner diameter that can be gear-shaped is limited by the cutter size: the cutter must fit inside the bore and have enough clearance to reciprocate without fouling the bore wall. The maximum inner diameter (ID \u2264 30 mm) for this product series reflects the smallest bore size at which Korea Ever-Power’s gear shaping capability produces the required involute profile accuracy. For larger inner diameters, see Korea Ever-Power’s broader ring gear range. Contact our team<\/a> with your specification.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Customer Reviews<\/h2>\n
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\n

“We manufacture servo planetary gearboxes and source M2 alloy steel involute internal ring gears from Korea Ever-Power. The weekly production photo reports confirmed heat treatment and gear shaping completion on schedule. Profile accuracy confirmed at our incoming gear analyzer \u2014 within our DIN 7 tolerance on all 50 pieces in the first batch. Single-facility production eliminates the quality handoff risk we had with our previous multi-supplier chain.”<\/p>\n

Kim Sang-min<\/strong>  |  Servo Gearbox Design Engineer, Incheon Precision Drives Co.  ·  Q1 2026<\/em><\/p>\n<\/div>\n

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“We design e-bike mid-drive planetary stages and specified stainless steel involute internal ring gears<\/a> M1.5, ID 28 mm from Korea Ever-Power. The involute profile’s centre-distance insensitivity compensates for our housing tolerance at the planet pin locations. Product drawing submitted as PDF \u2014 Korea Ever-Power produced a DWG confirmation drawing for approval before production. MOQ 50 pieces matched our first production run quantity.”<\/p>\n

Lee Hyun-seok<\/strong>  |  E-Bike Drivetrain Engineer, Gyeonggi Electric Bicycle Systems Co.  ·  Q4 2025<\/em><\/p>\n<\/div>\n

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“We make electric screwdriver planetary gear sets and needed M1 alloy involute ring gears ID 18 mm \u2014 at the fine pitch\/small bore boundary. Korea Ever-Power confirmed their shaping cutter capability for this combination, produced 50 sample pieces on schedule, and provided a QC inspection report with tooth profile measurement. All gears assembled into our planetary carrier without dimensional adjustment.”<\/p>\n

Park Jun-ho<\/strong>  |  Power Tool Gear Design Engineer, Busan Precision Tool Co.  ·  Q2 2026<\/em><\/p>\n<\/div>\n

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“We distribute involute internal gears to automotive and medical equipment manufacturers. Korea Ever-Power’s computerised production tracking means we can give our customers an accurate delivery date \u2014 not an estimate. Weekly photo reports passed directly to our customers who specify Korea Ever-Power as approved supplier after seeing the production visibility. No quality non-conformances in 12 months of supply.”<\/p>\n

Choi Sang-jun<\/strong>  |  Industrial Gear Distribution Manager, Daejeon Components Co.  ·  Q3 2025<\/em><\/p>\n<\/div>\n

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“We had a quality concern on a non-conforming delivery from a previous supplier. Korea Ever-Power’s QC department provided a root-cause analysis report identifying the non-conformance as a heat treatment temperature deviation, corrected the process, and re-manufactured the affected batch within 2 weeks. Replacement gears confirmed to specification on our incoming inspection.”<\/p>\n

Yoon Byeong-jun<\/strong>  |  Planetary Gear Procurement Manager, Ulsan Automation Systems Co.  ·  Q1 2025<\/em><\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Related Products<\/h2>\n
\n
\n
\n \"Planetary
\n <\/a><\/p>\n
\n

Ring Gears<\/h3>\n

Full ring gear range: planetary, aerospace, steel, automotive, industrial, wind turbine, flywheel, and cement mixer ring gears \u2014 all modules and materials.<\/p>\n

Browse Ring Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n

\n
\n \"Internal
\n <\/a><\/p>\n
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Helical Gears<\/h3>\n

Internal helical ring gears and external helical gears for lower noise parallel shaft and planetary drives \u2014 the helical complement to involute internal spur ring gears.<\/p>\n

Browse Helical Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n

\n
\n \"Industrial
\n <\/a><\/p>\n
\n

Ingranaggi conici<\/h3>\n

Bevel gears for right-angle drives in robot bases, differential drives, and output stage direction changes \u2014 the intersecting-shaft complement to involute internal gear planetary assemblies.<\/p>\n

Browse Bevel Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n

\n
\n \"Spur
\n <\/a><\/p>\n
\n

Spur Gears<\/h3>\n

External spur gears for sun pinion and planet gear roles in planetary assemblies with involute ring gears \u2014 same module and pressure angle ensures standard interchangeability.<\/p>\n

Browse Spur Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n<\/div>\n

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Request a Quotation for Involute Internal Gears<\/h3>\n

Send drawing (DWG\/IGS\/STEP\/PDF\/SolidWorks) or specify: module (up to M4.0), inner diameter (up to 30 mm), tooth count, material (alloy or stainless), surface treatment, and quantity (MOQ 50). Weekly production progress reports. QC inspection report included.<\/p>\n

Get a Quote Now<\/a>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

Korea Ever-Power involute internal gears are precision ring gears with standard involute tooth profile \u2014 42CrMo alloy steel, 20\u00b0 pressure angle, DIN 3962 Class 7. Size per drawing. Internal gear manufacturing capability: OD to 2,500 mm; ID min 50 mm (shaping) \/ 100 mm (grinding); face width to 500 mm; module to 45 mm (grinding); DIN Class 4 by tooth grinding; Ra 0.6 tooth finish. All materials and specifications customisable.<\/p>","protected":false},"featured_media":1594,"comment_status":"closed","ping_status":"open","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[4560],"product_tag":[],"class_list":["post-1593","product","type-product","status-publish","has-post-thumbnail","product_cat-ring-gear","pa_editor-cxm","first","instock","product-type-simple"],"_links":{"self":[{"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product\/1593","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/comments?post=1593"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/media\/1594"}],"wp:attachment":[{"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/media?parent=1593"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_brand?post=1593"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_cat?post=1593"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_tag?post=1593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}