내부 스퍼 기어 - 맞춤형 재질 및 크기, 최소 주문 수량 1개

Internal spur gears, 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 — 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.

Korea Ever-Power manufactures and exports fully custom internal spur gears with all parameters — tooth form, material, shape, grade, technique, pressure angle, diameter, and size — 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.

Steel & Alloy Grades

Steel (C45 / SAE1045), heat-treated steel, tool steel (D2, H13, M2 and equivalents), sintered steel (powder metallurgy). Widest strength and hardness range — induction hardening to 50–58 HRC, tool steel to 60–65 HRC. Best for: high-load industrial drives, machine tool gear trains, heavy-duty planetary ring gears.

Stainless Steel

SS303, SS304, SS316L, SS420 (hardenable). Corrosion resistant without coating — tooth surface integrity maintained in food processing and medical environments where coated steel gears would lose protection. Best for: food processing, medical, marine, pharmaceutical.

Cast Iron (Ductile & Gray)

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: large industrial ring gears, cement mixer ring gears, heavy-duty slewing rings.

Brass, Bronze & Copper

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: instrument drives, fuel system ring gears, non-sparking ATEX zone drives.

Aluminium

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

Plastic & Phenolic

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

Rollers and Conveyor Drives

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.

Electric Screwdrivers and Power Tools

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.

Pumps

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 — creating the variable volume chambers that pump fluid with very low pulsation.

Positioning Equipment

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.

Automotive Drives

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.

Bicycle Components

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.

How do I get a sample?

Before starting your sample, Korea Ever-Power confirms the product details — specifications, material, tooth form, pressure angle, and surface treatment — 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.

Why must the internal gear's pitch diameter be at least 1.5 times the pinion's?

The 1.5× 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 — 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.

What machining services are included in the internal spur gear production?

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.

What is the delivery time for internal spur gears?

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 — 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 for a lead time quote.

"We needed a single prototype internal spur gear in tool steel D2 for a new positioning machine design — 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."

Kim Hyeon-tae  |  Machine Tool Design Engineer, Incheon Precision Manufacturing Co.  ·  Q1 2026

"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 — 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."

Lee Dong-jun  |  Hydraulic Pump Design Engineer, Gyeonggi Fluid Power Co.  ·  Q4 2025

"We supply e-bike mid-drive planetary stages and use Korea Ever-Power's aluminium internal spur gears 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."

Park Sang-jun  |  E-Bike Drive System Engineer, Busan Electric Mobility Co.  ·  Q2 2026

"We distribute internal spur gears in 6 materials — steel, stainless, cast iron, brass, aluminium, and POM — 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."

Choi Min-seok  |  Industrial Gear Distribution Manager, Daejeon Parts Supply Co.  ·  Q3 2025

"We designed an internally geared bicycle hub with a non-standard pressure angle (22.5°) 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° pressure angle profile. No other supplier we contacted could produce the non-standard angle at this quantity."

Yoon Cheol-hoon  |  Bicycle Hub Transmission Designer, Ulsan Cycling Components Co.  ·  Q1 2025