{"id":1595,"date":"2026-07-15T03:49:57","date_gmt":"2026-07-15T03:49:57","guid":{"rendered":"https:\/\/gearrack.top\/product\/internal-spur-gear-custom-material-size-moq-1-unit\/"},"modified":"2026-07-15T03:50:06","modified_gmt":"2026-07-15T03:50:06","slug":"internal-spur-gear-custom-material-size-moq-1-unit","status":"publish","type":"product","link":"https:\/\/gearrack.top\/it\/product\/internal-spur-gear-custom-material-size-moq-1-unit\/","title":{"rendered":"Internal Spur Gear – Custom Material & Size, MOQ 1 Unit"},"content":{"rendered":"
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<\/p>\n

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

Internal spur gears<\/strong>, unlike external spur gears, have their teeth generated on the inner diameter of the gear blank. The mating pinion runs inside the ring, with both gears rotating in the same direction. Internal spur gears are generally more robust and more efficient than the mating pinion gear \u2014 the concave internal tooth surface produces a larger contact patch than the convex-on-convex contact of an external pair at the same module and face width, which reduces the Hertzian contact stress and distributes the load more evenly across the tooth face. The pitch diameter of the internal spur gear must be at least 1.5 times the pitch diameter of the mating pinion; if this condition is not met, interference between the tips of the teeth will occur.<\/p>\n

Korea Ever-Power manufactures and exports fully custom internal spur gears<\/a> with all parameters \u2014 tooth form, material, shape, grade, technique, pressure angle, diameter, and size \u2014 specified per the customer’s drawing or requirement. MOQ 1 unit. 14 material options covering the full spectrum from engineering plastics to tool steel. All machining services in-house from a single facility focused on CNC machining since 2007.<\/p>\n<\/p><\/div>\n<\/div>\n

Internal spur gears allow designers to achieve higher contact ratios and drive ratios than standard external spur gears at shorter centre distances. They also enable a velocity change without a directional change \u2014 something that would require an idler gear with classic external spur gears, adding an additional gear, shaft, bearing, and housing bore to the design. This simplification is why internal spur gears are specified for compact mechanism designs wherever coaxial or near-coaxial input and output shafts are required.<\/p>\n

<\/p>\n

Technical Specifications<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Internal Spur Gear \u2014 Product Specification<\/th>\n<\/tr>\n<\/thead>\n
Tooth Form<\/strong><\/td>\nAs per customer requirement (involute standard; cycloidal and other profiles on request)<\/td>\n<\/tr>\n
Material<\/strong><\/td>\nAs per customer requirement \u2014 see full materials list below<\/td>\n<\/tr>\n
Shape<\/strong><\/td>\nAs per customer requirement (standard round \/ annular; flanged, segmented, or custom profile available)<\/td>\n<\/tr>\n
Grade \/ Accuracy<\/strong><\/td>\nAs per customer requirement (DIN 6\u20139 or AGMA equivalent)<\/td>\n<\/tr>\n
Technique<\/strong><\/td>\nAs per customer requirement \u2014 see machining services list below<\/td>\n<\/tr>\n
Pressure Angle<\/strong><\/td>\nAs per customer requirement (standard 14\u00b0, 20\u00b0, 25\u00b0; non-standard on request)<\/td>\n<\/tr>\n
Diameter<\/strong><\/td>\nAs per customer requirement<\/td>\n<\/tr>\n
Size<\/strong><\/td>\nAs per customer requirement<\/td>\n<\/tr>\n
Minimum Order Quantity<\/strong><\/td>\n1 unit \u2014 prototype and single-piece production accepted<\/td>\n<\/tr>\n
Machining Services<\/strong><\/td>\nPrecision blanking, sawing, milling, drilling, tapping, broaching, finishing<\/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<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

Materials<\/h2>\n

\"Steel<\/p>\n

Korea Ever-Power can custom manufacture internal spur gears from the widest available material range \u2014 14 material families covering every standard application from food-grade plastic drives to hardened tool steel precision gearboxes:<\/p>\n

\n
\n

Steel & Alloy Grades<\/h3>\n

Steel (C45 \/ SAE1045), heat-treated steel, tool steel (D2, H13, M2 and equivalents), sintered steel (powder metallurgy). Widest strength and hardness range \u2014 induction hardening to 50\u201358 HRC, tool steel to 60\u201365 HRC. Best for:<\/strong> high-load industrial drives, machine tool gear trains, heavy-duty planetary ring gears.<\/p>\n<\/p><\/div>\n

\n

Stainless Steel<\/h3>\n

SS303, SS304, SS316L, SS420 (hardenable). Corrosion resistant without coating \u2014 tooth surface integrity maintained in food processing and medical environments where coated steel gears would lose protection. Best for:<\/strong> food processing, medical, marine, pharmaceutical.<\/p>\n<\/p><\/div>\n

\n

Cast Iron (Ductile & Gray)<\/h3>\n

Ductile iron (nodular cast iron) and gray iron. Good vibration damping, easy castability for complex flanged ring gear shapes, low cost per kg vs steel for large ring gear blanks. Best for:<\/strong> large industrial ring gears, cement mixer ring gears, heavy-duty slewing rings.<\/p>\n<\/p><\/div>\n

\n

Brass, Bronze & Copper<\/h3>\n

Brass (CuZn), bronze (CuSn, CuAl), copper. Non-sparking, self-lubricating against steel pinion, excellent corrosion resistance, best machinability for fine-pitch internal teeth. Best for:<\/strong> instrument drives, fuel system ring gears, non-sparking ATEX zone drives.<\/p>\n<\/p><\/div>\n

\n

Aluminium<\/h3>\n

Aluminium alloy (6061-T6, 7075-T6, 2024). 78% lighter than steel at the same volume. Anodising provides corrosion and wear protection. Best for:<\/strong> UAV and satellite ring gears, portable equipment planetary drives, weight-critical applications where load is moderate.<\/p>\n<\/p><\/div>\n

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Plastic & Phenolic<\/h3>\n

POM (Delrin), PA6, PA66, PEEK, phenolic (Bakelite). Self-lubricating, non-magnetic, corrosion resistant, lightweight, quiet. Best for:<\/strong> low-load consumer product drives, home appliances, toy gear trains, non-metallic electrical isolation requirements.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Internal vs External Spur Gear \u2014 Engineering Comparison<\/h2>\n

\"types<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/th>\nInternal Spur Gear \u2605<\/th>\nExternal Spur Gear<\/th>\n<\/tr>\n<\/thead>\n
Tooth Location<\/strong><\/td>\nInner bore \u2713<\/td>\nOuter OD<\/td>\n<\/tr>\n
Rotation Direction<\/strong><\/td>\nSame as pinion \u2713<\/td>\nOpposite to pinion<\/td>\n<\/tr>\n
Centre Distance<\/strong><\/td>\nRring<\/sub> \u2212 Rpinion<\/sub> (smaller) \u2713<\/td>\nRingranaggio<\/sub> + Rpinion<\/sub> (larger)<\/td>\n<\/tr>\n
Contact Ratio<\/strong><\/td>\nHigher (1.7\u20132.2) \u2713<\/td>\nLower (1.4\u20131.6)<\/td>\n<\/tr>\n
Tooth Surface Contact<\/strong><\/td>\nConforming (concave) \u2713<\/td>\nNon-conforming (convex)<\/td>\n<\/tr>\n
Load per Tooth Width<\/strong><\/td>\nHigher capacity \u2713<\/td>\nStandard capacity<\/td>\n<\/tr>\n
Idler Gear Needed for Same-Direction Output<\/strong><\/td>\nNo \u2713<\/td>\nYes<\/td>\n<\/tr>\n
Pitch Diameter Constraint<\/strong><\/td>\nPDring<\/sub> \u2265 1.5 \u00d7 PDpinion<\/sub><\/td>\nNo constraint on ratio<\/td>\n<\/tr>\n
Manufacturing Complexity<\/strong><\/td>\nHigher (internal cutting)<\/td>\nLower \u2713<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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

<\/p>\n

Applications<\/h2>\n

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

\n
\n
<\/div>\n

Rollers and Conveyor Drives<\/h3>\n

Internal spur ring gears in conveyor roller drive planetary stages and belt conveyor drive reducers. The compact, coaxial planetary arrangement enabled by the internal spur gear suits the inline drive motor-to-roller configuration standard in modern conveyor design.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

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

Internal spur gears in electric screwdriver planetary torque limiters, cordless drill two-speed planetary gearboxes, and rotary tool reduction stages. The same-direction rotation eliminates the need for a reversal stage in the tool’s planetary gearbox.<\/p>\n<\/p><\/div>\n

\n
\u26fd<\/div>\n

Pumps<\/h3>\n

Internal spur (gerotor) gears in gear pump inner rotor drives and hydraulic motor internal gear sets. The gerotor pump’s internal gear is an internal spur ring gear whose inner involute teeth mesh with a smaller external rotor \u2014 creating the variable volume chambers that pump fluid with very low pulsation.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Positioning Equipment<\/h3>\n

Internal spur gears in servo positioning table planetary drives, camera gimbal planetary stages, and telescope azimuth positioning drives. The internal gear’s higher contact ratio and shorter centre distance produce a stiffer, more accurate positioning drive than an equivalent external gear pair.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Automotive Drives<\/h3>\n

Internal spur gears in automatic transmission planetary stages, EV motor planetary reducers, electric power steering planetary gears, and seat adjuster mechanism drives. The automotive internal spur gear’s velocity change without directional change property allows the automatic transmission to select forward ratios without a direction-reversing gear in the power path.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Bicycle Components<\/h3>\n

Internal spur gears in internally geared bicycle hub transmissions (3-speed, 8-speed, 11-speed planetary hubs), e-bike mid-drive planetary stages, and pedal-assist drive unit planetary reduction sets. The internal gear hub’s coaxial input-output arrangement fits inside the rear wheel hub envelope with no external derailleur exposed to dirt and impact.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

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

How do I get a sample?<\/p>\n

Before starting your sample, Korea Ever-Power confirms the product details \u2014 specifications, material, tooth form, pressure angle, and surface treatment \u2014 with you to avoid any possible misunderstandings. Once confirmed, sample production begins. The minimum order quantity is 1 unit, so a single prototype internal spur gear can be ordered. Send the drawing or specification to begin the quotation and sample process.<\/p>\n<\/div>\n

\n
\n

Why must the internal gear’s pitch diameter be at least 1.5 times the pinion’s?<\/p>\n

The 1.5\u00d7 pitch diameter condition (approximately) is the interference avoidance condition for internal-external gear pairs at standard pressure angle and addendum. If the ring gear is too small relative to the pinion, the tips of the ring gear teeth foul the tips of the pinion teeth as they enter and leave the mesh \u2014 a condition called tip interference that prevents the gear pair from operating. Korea Ever-Power’s engineering team checks the interference condition for every custom internal spur gear design and will flag any tooth count combination that violates it before production.<\/p>\n<\/div>\n

\n
\n

What machining services are included in the internal spur gear production?<\/p>\n

Korea Ever-Power provides the complete production sequence in-house: precision blanking (cutting the ring gear blank from bar stock or plate), sawing, milling (OD, face, and flange features), drilling (mounting holes, oil holes, tapped features), tapping (thread cutting in holes), broaching (keyways and internal splines), and finishing (deburring, surface treatment, final inspection). All steps handled in one location means no sub-contractor coordination delays and no quality handoff risk between operations.<\/p>\n<\/div>\n

\n
\n

What is the delivery time for internal spur gears?<\/p>\n

Sample lead time is typically 20 business days from drawing confirmation. Bulk production lead time is 25 business days for standard materials and treatments. The computerised production system logs every step from order receipt through shipment \u2014 customers who cannot visit the factory receive weekly progress reports with digital photos and videos. If a specific delivery date is critical, contact Korea Ever-Power at the enquiry stage and the production schedule will be confirmed before order placement. Contact our team<\/a> for a lead time quote.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

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

“We needed a single prototype internal spur gear in tool steel D2 for a new positioning machine design \u2014 a very specific requirement that many suppliers could not meet at MOQ 1. Korea Ever-Power produced the single-piece sample from our DWG drawing, confirmed the tooth profile on their gear measurement machine, and delivered with a QC report. The gear measured within our tolerance on incoming inspection.”<\/p>\n

Kim Hyeon-tae<\/strong>  |  Machine Tool Design Engineer, Incheon Precision Manufacturing Co.  ·  Q1 2026<\/em><\/p>\n<\/div>\n

\n

“We manufacture gerotor hydraulic pumps and source our internal spur ring gears in ductile iron from Korea Ever-Power. The broaching service for the keyway on the inner bore is done in-house at Korea Ever-Power \u2014 eliminating the sub-contractor step our previous supplier used. Weekly photo reports showed us the gear shaping and broaching operations, which confirmed the process was correct before we committed to the production order.”<\/p>\n

Lee Dong-jun<\/strong>  |  Hydraulic Pump Design Engineer, Gyeonggi Fluid Power Co.  ·  Q4 2025<\/em><\/p>\n<\/div>\n

\n

“We supply e-bike mid-drive planetary stages and use Korea Ever-Power’s aluminium internal spur gears<\/a> for the weight-critical planetary ring gear in our 250W motor drive. Aluminium ring gear weight: 42 g vs 115 g for the equivalent steel ring gear. At 50,000 units per year, the weight saving is significant for our e-bike system weight budget. DIN 7 profile confirmed on all gears in the first production batch.”<\/p>\n

Park Sang-jun<\/strong>  |  E-Bike Drive System Engineer, Busan Electric Mobility Co.  ·  Q2 2026<\/em><\/p>\n<\/div>\n

\n

“We distribute internal spur gears in 6 materials \u2014 steel, stainless, cast iron, brass, aluminium, and POM \u2014 to industrial and consumer product manufacturers. Korea Ever-Power’s integrated single-facility production covers all six materials without separate tooling suppliers or sub-contracting, which means our customers receive a consistent quality level regardless of which material they specify.”<\/p>\n

Choi Min-seok<\/strong>  |  Industrial Gear Distribution Manager, Daejeon Parts Supply Co.  ·  Q3 2025<\/em><\/p>\n<\/div>\n

\n

“We designed an internally geared bicycle hub with a non-standard pressure angle (22.5\u00b0) for an improved interference margin at our tooth count combination. Korea Ever-Power confirmed their gear shaping tooling could cut the non-standard pressure angle, produced 20 prototype internal spur gears, and provided the gear measurement trace confirming the 22.5\u00b0 pressure angle profile. No other supplier we contacted could produce the non-standard angle at this quantity.”<\/p>\n

Yoon Cheol-hoon<\/strong>  |  Bicycle Hub Transmission Designer, Ulsan Cycling Components 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, involute, steel, industrial, automotive, flywheel, wind turbine, and more \u2014 all materials and specifications.<\/p>\n

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

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

Helical Gears<\/h3>\n

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

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

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

Ingranaggi conici<\/h3>\n

Bevel gears for right-angle drives in robot bases, differential drives, and output direction changes \u2014 the intersecting-shaft complement to internal spur 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 with internal spur ring gears \u2014 same module ensures standard interchangeability.<\/p>\n

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

\n

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

All parameters per customer requirement. MOQ 1 unit. Send drawing (DWG\/IGS\/STEP\/PDF) or specify: tooth form, material, shape, grade, technique, pressure angle, diameter, size, and quantity. Weekly production progress reports included.<\/p>\n

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

Korea Ever-Power internal spur gears are fully custom internal ring gears \u2014 tooth form, material, shape, grade, technique, pressure angle, diameter, and size all per customer requirement. MOQ 1 unit. Materials: steel, stainless steel, heat-treated steel, sintered steel, tool steel, ductile iron, gray iron, brass, bronze, copper, cast iron, aluminium, plastic, phenolic. Services: precision blanking, sawing, milling, drilling, tapping, broaching, finishing. 30 sets CNC, 15 sets CNC turning, 10 sets sheet metal fabrication \u2014 all in-house. Focus on CNC machining since 2007.<\/p>","protected":false},"featured_media":1596,"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-1595","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\/1595","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=1595"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/media\/1596"}],"wp:attachment":[{"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/media?parent=1595"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_brand?post=1595"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_cat?post=1595"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/gearrack.top\/it\/wp-json\/wp\/v2\/product_tag?post=1595"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}