{"id":1591,"date":"2026-07-15T03:49:57","date_gmt":"2026-07-15T03:49:57","guid":{"rendered":"https:\/\/gearrack.top\/product\/planetary-ring-gear-42crmo-mn6-z109-din-class-7\/"},"modified":"2026-07-15T03:50:00","modified_gmt":"2026-07-15T03:50:00","slug":"planetary-ring-gear-42crmo-mn6-z109-din-class-7","status":"publish","type":"product","link":"https:\/\/gearrack.top\/ko\/product\/planetary-ring-gear-42crmo-mn6-z109-din-class-7\/","title":{"rendered":"Planetary Ring Gear – 42CrMo, Mn6 Z109, DIN Class 7"},"content":{"rendered":"
\n

<\/p>\n

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

A planetary ring gear<\/strong> is the outermost fixed (or output) element of a planetary gear transmission \u2014 the annular internal gear whose inner teeth mesh simultaneously with multiple planet gears orbiting a central sun gear. The planetary transmission is a gear transmission in which at least one gear has a collective shaft that rotates around the central shaft; the outermost ring of this transmission is the ring gear. In a standard planetary stage the ring gear is on the same axis as the planet carrier, and it is the element that makes the planetary arrangement unique: by holding the ring gear fixed and driving the sun, the planet carrier produces an output speed reduction equal to 1 + Zring<\/sub>\/Zsun<\/sub> \u2014 all within a coaxial, compact envelope no external gear train can match.<\/p>\n

Korea Ever-Power produces precision planetary ring gears<\/a> across module M3 to M12 and beyond in the full range of engineering materials \u2014 C45 steel, alloy steel, brass, stainless steel, copper, POM, aluminium. DIN 6\u20139 precision. Full surface treatment range. Sample 20 business days; bulk 25 days. T\/T or L\/C.<\/p>\n<\/p><\/div>\n<\/div>\n

The traditional method of forming inner ring gear teeth \u2014 inserting, pushing, and pulling (broaching) \u2014 has low material utilisation, long process time, high energy consumption, and produces internal ring gears with comparatively low surface hardness. Korea Ever-Power applies modern CNC internal gear shaping and hard finishing processes that overcome all four limitations: higher material yield, shorter production cycle, lower per-unit energy, and tooth surface hardness matched to the application requirement.<\/p>\n

<\/p>\n

How the Planetary Ring Gear Functions<\/h2>\n

\"types<\/p>\n

A planetary gear stage has four elements: the sun gear (input), the planet gears (idlers carried on the carrier), the planet carrier (output or fixed), and the ring gear (fixed or output). The ring gear’s role and the resulting gear ratio depend on which element is held fixed:<\/p>\n

\n\n\n\n\n\n\n\n
Fixed Element<\/th>\nInput<\/th>\nOutput<\/th>\nRatio Formula<\/th>\nCommon Use<\/th>\n<\/tr>\n<\/thead>\n
Ring gear \u2605<\/td>\nSun gear<\/td>\nPlanet carrier<\/td>\n1 + Zring<\/sub>\/Zsun<\/sub><\/td>\nSpeed reducer \u2014 most common arrangement<\/td>\n<\/tr>\n
Planet carrier<\/td>\nSun gear<\/td>\nRing gear<\/td>\nZring<\/sub>\/(Zring<\/sub>+Zsun<\/sub>)<\/td>\nSpeed increaser (ring gear output)<\/td>\n<\/tr>\n
Sun gear<\/td>\nPlanet carrier<\/td>\nRing gear<\/td>\nZring<\/sub>\/Zplanet<\/sub> + 1<\/td>\nDifferential \/ CVT applications<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

In the most common arrangement (ring gear fixed, sun input, carrier output), the ring gear carries the full reaction torque of the stage at all times \u2014 which is why the ring gear is the most structurally loaded element in the planetary assembly and why its material, heat treatment, and tooth accuracy specifications are the primary design drivers for planetary gearbox performance.<\/p>\n

\n
\n

Compact Structure \u2014 Small Size, Light Weight<\/h3>\n

Planetary transmission has the characteristics of planetary motion and power split. Multiple planet gears share the load simultaneously, and the coaxial arrangement means the ring gear and sun share the same centreline \u2014 producing a gearbox that is shorter and lighter than an equivalent-ratio external gear train. A 5:1 planetary stage is typically 40\u201360% of the volume of a 5:1 external gear pair at the same torque rating.<\/p>\n<\/p><\/div>\n

\n

Power Split \u2014 Load Sharing<\/h3>\n

A three-planet stage splits the transmitted torque equally across three planet-ring gear meshes. Each planet gear contacts the ring gear at the same time, sharing one third of the total torque at each contact. This load splitting reduces the tooth load at each mesh to one third of what a single-planet stage would require \u2014 allowing a smaller ring gear module (and lighter assembly) for the same output torque.<\/p>\n<\/p><\/div>\n

\n

High Transmission Efficiency<\/h3>\n

A single planetary stage achieves 97\u201399% power transmission efficiency \u2014 close to the efficiency of a single external spur gear pair. Multi-stage planetary gearboxes maintain high efficiency because each planet-ring gear mesh is an internal contact (conforming, lower friction than external convex-on-convex contact). This high efficiency is why planetary gearboxes are specified for servo drives, robot joints, and EV transmissions where thermal management of losses is a design constraint.<\/p>\n<\/p><\/div>\n

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Wide Ratio Range<\/h3>\n

A single planetary stage achieves ratios from approximately 3:1 to 12:1 depending on the ring-to-sun tooth count ratio. Two stages in series achieve up to 144:1 in the same coaxial form factor. Three stages reach 1,728:1. This wide ratio range \u2014 all in a compact, coaxial package \u2014 is the primary reason planetary gearboxes dominate in robot joint drives, servo actuators, wind turbine pitch and yaw drives, and aerospace actuators.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Technical Specifications<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Planetary Ring Gear \u2014 Product Specification<\/th>\n<\/tr>\n<\/thead>\n
Module Range<\/strong><\/td>\nM3, M4, M5, M8, M12 and non-standard \u2014 custom per drawing<\/td>\n<\/tr>\n
\uc7ac\ub8cc<\/strong><\/td>\nBrass, C45 steel, stainless steel, copper, POM, aluminium, alloy \u2014 per drawing<\/td>\n<\/tr>\n
Surface Treatment<\/strong><\/td>\nZinc-plated, nickel plated, passivation, oxidation, anodisation, Geomet, Dacromet, black oxide, phosphatising, powder coating, electrophoresis<\/td>\n<\/tr>\n
Standard<\/strong><\/td>\nISO, DIN, ANSI, JIS, BS, and non-standard<\/td>\n<\/tr>\n
Precision<\/strong><\/td>\nDIN 6, DIN 7, DIN 8, DIN 9<\/td>\n<\/tr>\n
Teeth Treatment<\/strong><\/td>\nHardened, milled, or ground<\/td>\n<\/tr>\n
Tolerance<\/strong><\/td>\n0.001 mm \u2013 0.01 mm \u2013 0.1 mm per accuracy grade<\/td>\n<\/tr>\n
\ub9c8\uce58\ub2e4<\/strong><\/td>\nShot\/sandblast, heat treatment, annealing, tempering, polishing, anodising, zinc-plated<\/td>\n<\/tr>\n
Packing<\/strong><\/td>\nPlastic bag + cartons, or wooden packing for large ring gears<\/td>\n<\/tr>\n
Payment Terms<\/strong><\/td>\nT\/T, L\/C<\/td>\n<\/tr>\n
Sample Lead Time<\/strong><\/td>\n20 business days; sample price USD 2\u2013100; express freight paid by customer<\/td>\n<\/tr>\n
Bulk Lead Time<\/strong><\/td>\n25 business days<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

Material Selection<\/h2>\n

\"Steel<\/p>\n

\n
\n

C45 Steel \u2014 Standard Grade<\/h3>\n

The most economical planetary ring gear material. Induction hardened to 50\u201358 HRC on the tooth surface. Suitable for general industry planetary gearboxes, conveyor drives, and servo reducer stages at moderate torque density. Surface treatment required for corrosion protection.<\/p>\n<\/p><\/div>\n

\n

Alloy Steel \u2014 High Duty<\/h3>\n

42CrMo or 20CrMnTi carburised ring gears for high-torque planetary stages \u2014 robot joints, EV final drives, wind turbine pitch actuators. Case hardness 58\u201362 HRC; tough core absorbs shock loads from sudden load application.<\/p>\n<\/p><\/div>\n

\n

Stainless Steel \u2014 Corrosive Environments<\/h3>\n

SS304 or SS316L planetary ring gears for food processing planetary drives, marine propulsion auxiliary stages, and medical robot joint actuators. Corrosion resistance maintained at the inner tooth surface without coating.<\/p>\n<\/p><\/div>\n

\n

Brass \/ Aluminium \u2014 Light Duty<\/h3>\n

Brass ring gears for instrument planetary drives and non-sparking applications. Aluminium ring gears where weight is critical \u2014 UAV actuators, portable servo drives, and precision instrument gearboxes.<\/p>\n<\/p><\/div>\n

\n

POM \/ Engineering Plastic<\/h3>\n

POM or PA planetary ring gears for low-load, low-noise plastic planetary drives in home appliances, toy drives, and light automation. Self-lubricating, non-magnetic, corrosion resistant \u2014 no surface treatment required.<\/p>\n<\/p><\/div>\n

\n

Copper \u2014 Electrical Applications<\/h3>\n

Copper ring gears in planetary drives where the gear train must conduct a continuous electrical ground path \u2014 semiconductor handling equipment and precision measurement instrument planetary drives where static charge accumulation must be prevented.<\/p>\n<\/p><\/div>\n<\/div>\n


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

<\/p>\n

\uc751\uc6a9 \ud504\ub85c\uadf8\ub7a8<\/h2>\n

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

\n
\n
<\/div>\n

Robot Joint Drives<\/h3>\n

Carburised 20CrMnTi planetary ring gears M3\u2013M5 DIN 6\u20137 in collaborative robot (cobot) and industrial robot joint planetary reducers. High torque density and compact coaxial form factor are the two properties that make planetary ring gears the universal choice for robot joint drives.<\/p>\n<\/p><\/div>\n

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

Automatic Controlling Machines<\/h3>\n

C45 or alloy steel planetary ring gears M4\u2013M8 in servo-driven positioning systems, CNC axis drives, and linear actuator planetary stages. The planetary gearbox’s coaxial arrangement makes it the natural choice for servo motor output stages where motor and load share the same axis.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Solar Energy Equipment<\/h3>\n

Alloy steel planetary ring gears M5\u2013M12 in solar tracker azimuth and elevation drive planetary gearboxes. The planetary stage’s high torque density in a sealed housing suits the outdoor solar tracker’s low maintenance, long service life requirement at moderate drive cycle frequency.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Medical Equipment<\/h3>\n

SS316L or aluminium planetary ring gears M3\u2013M5 DIN 6 in surgical robot joint reducers, infusion pump drive planetary stages, and medical imaging table positioning planetary gearboxes. Non-magnetic and autoclave-compatible stainless steel for MRI-adjacent medical drives.<\/p>\n<\/p><\/div>\n

\n
\ufe0f<\/div>\n

Parking Systems<\/h3>\n

Alloy steel planetary ring gears M5\u2013M12 with Dacromet surface treatment in automated parking system lift drives. Outdoor corrosion protection and high drive torque in a compact, sealed planetary gearbox suit this intermittent-duty, high-cycle application.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

High-Speed Rail and Aviation<\/h3>\n

Precision alloy steel planetary ring gears M5\u2013M12 DIN 6\u20137 in rail vehicle door actuators, aircraft landing gear actuator planetary stages, and airport gate drive planetary gearboxes. Full material traceability and dimensional inspection report supplied as standard for rail and aviation procurement.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Advantages of Planetary Transmission<\/h2>\n

\"measuring<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
Property<\/th>\nPlanetary (Ring Gear) \u2605<\/th>\nExternal Spur Stage<\/th>\nWorm Gear Stage<\/th>\nCycloidal Stage<\/th>\n<\/tr>\n<\/thead>\n
Shaft Arrangement<\/strong><\/td>\nCoaxial \u2713<\/td>\nParallel offset<\/td>\nRight angle<\/td>\nCoaxial<\/td>\n<\/tr>\n
Torque Density<\/strong><\/td>\nHighest \u2713<\/td>\nModerate<\/td>\nModerate<\/td>\nHigh<\/td>\n<\/tr>\n
Efficiency (%)<\/strong><\/td>\n97\u201399% \u2713<\/td>\n96\u201399%<\/td>\n50\u201390%<\/td>\n90\u201395%<\/td>\n<\/tr>\n
Ratio Per Stage<\/strong><\/td>\n3:1 \u2013 12:1<\/td>\n1.5:1 \u2013 6:1<\/td>\n5:1 \u2013 100:1<\/td>\n6:1 \u2013 87:1<\/td>\n<\/tr>\n
Backlash<\/strong><\/td>\nLow (arc-min) \u2713<\/td>\nLow<\/td>\nModerate<\/td>\nLowest \u2713<\/td>\n<\/tr>\n
Self-Locking<\/strong><\/td>\nNo<\/td>\nNo<\/td>\nYes (high ratio) \u2713<\/td>\nNo<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

Frequently Asked Questions<\/h2>\n
\n
\n

Why does a planetary ring gear need to have more teeth than the sun gear?<\/p>\n

In a valid planetary gear stage, the ring gear tooth count must equal the sum of the sun gear tooth count and twice the planet gear tooth count: Zring<\/sub> = Zsun<\/sub> + 2 \u00d7 Zplanet<\/sub>. This is the assembly condition that ensures all planet gears can be assembled into the stage simultaneously. If this condition is not met, the planets will not align with the ring gear teeth at the same angular positions on the planet carrier, and the stage cannot be assembled. Additionally, the ring gear must have sufficiently more teeth than the mating pinion to avoid interference \u2014 typically at least 12\u201315 more teeth at standard 20\u00b0 pressure angle.<\/p>\n<\/div>\n

\n
\n

Why is the inner ring gear difficult to process, and how does Korea Ever-Power overcome this?<\/p>\n

The traditional internal ring gear tooth cutting methods \u2014 broaching (pulling teeth), shaping (inserting teeth), and slotting (pushing teeth) \u2014 are constrained by the limited space inside the ring gear bore, which restricts tool size, chip clearance, and coolant access. The result is a slow process with low material utilisation and limited achievable surface hardness after heat treatment. Korea Ever-Power uses modern CNC internal gear shaping machines with profile-ground form cutters that overcome the space constraint, combined with internal bore grinding after heat treatment to achieve DIN 6\u20137 accuracy on the finished tooth surface \u2014 producing planetary ring gears with the hardness and accuracy that the traditional methods cannot achieve.<\/p>\n<\/div>\n

\n
\n

What is the difference between a planetary ring gear and a flywheel ring gear?<\/p>\n

A planetary ring gear (also called an annular ring gear or internal ring gear) has its teeth on the inner bore and meshes with an internal planet pinion running inside the ring \u2014 used in planetary gearboxes. A flywheel ring gear has its teeth on the outer rim and meshes with an external starter motor pinion \u2014 used in engine starting systems. Both are annular (ring-shaped) gears, but they differ in tooth location (inner vs outer), mesh geometry (internal vs external), and application. Korea Ever-Power produces both types; this page covers the internal planetary ring gear. The flywheel ring gear for agricultural tractor applications is a separate product in the range.<\/p>\n<\/div>\n

\n
\n

What surface treatment is recommended for planetary ring gears in outdoor or corrosive environments?<\/p>\n

For outdoor applications (solar tracker planetary drives, parking system gearboxes), Dacromet or Geomet coating on the external surfaces of the ring gear housing provides 480\u20131,000+ hours salt spray resistance without hydrogen embrittlement risk \u2014 critical for hardened ring gears where electroplating could cause hydrogen embrittlement cracking. The internal tooth surface, being a precision ground surface running in oil, does not receive a coating \u2014 the tooth surface corrosion protection relies on the gear oil during operation and preservation oil (or VCI packaging) during storage and transit. Contact our team<\/a> with the specific environment for a surface treatment recommendation.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Customer Reviews<\/h2>\n
\n
\n

“We manufacture collaborative robot joints and use 20CrMnTi carburised planetary ring gears M4 DIN 7 from Korea Ever-Power. The internal gear shaping and post-hardening grinding produces the DIN 7 tooth profile accuracy our planetary reducer requires for arc-minute backlash. Torque density confirmed to our calculations \u2014 the ring gear is the limiting element, and Korea Ever-Power’s heat treatment process hits the 58\u201362 HRC surface hardness specification consistently.”<\/p>\n

Kim Jae-hyeon<\/strong>  |  Robot Joint Drive Engineer, Incheon Robotics Co.  ·  Q1 2026<\/em><\/p>\n<\/div>\n

\n

“We supply solar tracker drive systems and source alloy steel planetary ring gears<\/a> M8 DIN 8 with Dacromet surface treatment from Korea Ever-Power. Four years of outdoor service in coastal salt air \u2014 zero ring gear failures across 240 tracker units in the field. The planetary gearbox’s sealed design with Dacromet-coated ring gear housing eliminates corrosion in this aggressive outdoor environment.”<\/p>\n

Lee Gyeong-hun<\/strong>  |  Solar Tracker Drive Systems Engineer, Gyeonggi Renewable Energy Co.  ·  Q4 2025<\/em><\/p>\n<\/div>\n

\n

“We manufacture servo planetary gearboxes for CNC machine tool axes and source C45 induction-hardened ring gears M5 DIN 7 from Korea Ever-Power. Sample confirmed in 20 business days. Tooth profile accuracy checked by our gear analyzer \u2014 within DIN 7 on all 8 sample gears. Production batch (200 pieces) delivered in 25 days as quoted. T\/T payment, no issues.”<\/p>\n

Park Cheol-min<\/strong>  |  CNC Drive Systems Engineer, Busan Machine Tool Systems Co.  ·  Q2 2026<\/em><\/p>\n<\/div>\n

\n

“We import planetary ring gears M3\u2013M12 in five materials \u2014 steel, stainless, brass, aluminium, and POM \u2014 for distribution to servo drive manufacturers. Korea Ever-Power supplies all five materials across all modules from a single facility with a single quality system. DIN 6\u20139 per material and module confirmed by dimensional report. One supplier, full range.”<\/p>\n

Choi Byeong-min<\/strong>  |  Industrial Drive Parts Import Manager, Daejeon Servo Drive Distribution Co.  ·  Q3 2025<\/em><\/p>\n<\/div>\n

\n

“We need SS316L planetary ring gears M3 DIN 6 for surgical robot joint planetary stages. Korea Ever-Power produced sample ring gears in 20 days. Feritscope non-magnetic confirmation (\u2264 1.4 Ferite number) provided with delivery. Autoclave sterilisation test passed (134\u00b0C, 50 cycles) \u2014 no dimensional change on our CMM re-measurement. Production order placed.”<\/p>\n

Yoon Seo-yeon<\/strong>  |  Medical Robot Component Engineer, Ulsan Medical Robotics Co.  ·  Q1 2025<\/em><\/p>\n<\/div>\n<\/div>\n

<\/p>\n

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

Ring Gears<\/h3>\n

Full ring gear range: aerospace, involute, internal spur, steel, industrial, automotive, flywheel, cement mixer, wind turbine, and alloy ring gears.<\/p>\n

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

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

External helical gears for lower-noise parallel shaft drives \u2014 the sun gear and planet gear complement to planetary ring gear assemblies.<\/p>\n

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

\n
\n \"\ubca0\ubca8
\n <\/a><\/p>\n
\n

\ubca0\ubca8 \uae30\uc5b4<\/h3>\n

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

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

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

Spur Gears<\/h3>\n

External spur gears for sun pinion and planet gear roles in planetary assemblies \u2014 the external gear complement to planetary ring gears across all modules and materials.<\/p>\n

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

\n

Request a Quotation for Planetary Ring Gears<\/h3>\n

Send drawing or specify: module (M3\u2013M12), tooth count, OD\/ID, face width, material, heat treatment, surface treatment, accuracy grade (DIN 6\u20139), and quantity. Sample 20 days (USD 2\u2013100); bulk 25 days. T\/T or L\/C.<\/p>\n

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

Korea Ever-Power planetary ring gears are large-format alloy steel ring gears for planetary gearbox stages \u2014 standard: 42CrMo, involute, 20\u00b0 pressure angle, DIN 3962 Class 7, Mn=6 Z=109. Internal gear capability: OD to 2,500 mm; ID min 50 mm; face width to 500 mm; module to 45 mm (grinding); DIN Class 4 by tooth grinding, Ra 0.6. Materials: carbon steel (SAE1020, SAE1045), alloy steel (20CrMnTi, 16MnCr5, 42CrMo), brass\/bronze. Module 1.0\u20138.0+. OD \u00b10.005 mm tolerance.<\/p>","protected":false},"featured_media":1592,"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-1591","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\/ko\/wp-json\/wp\/v2\/product\/1591","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/comments?post=1591"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/media\/1592"}],"wp:attachment":[{"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/media?parent=1591"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/product_brand?post=1591"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/product_cat?post=1591"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/gearrack.top\/ko\/wp-json\/wp\/v2\/product_tag?post=1591"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}