Steel Internal Gear – Mild Steel, 100mm OD, 45HRC, Custom

Steel internal gears are annular ring gears with teeth cut on the inner bore, manufactured in mild steel with additional grades available per specification. The standard configuration — 100 mm outer diameter, round shape, powder-coated surface, 45 HRC tooth hardness — serves the broadest range of industrial internal gear applications: planetary gearboxes, machine tool drives, conveyor system reducers, and general industrial gear stages where mild steel's combination of machinability, weldability, and moderate strength provides the optimum cost-performance balance. All specifications are customisable per the customer's drawing, including material grade, diameter, face width, tooth count, module, pressure angle, bore dimensions, and surface treatment.

Korea Ever-Power holds ISO 9001 and CQC certification. OEM production accepted with customer authorisation. Steel internal gears are delivered by express, air, sea, or train depending on destination and urgency. Payment: T/T, L/C, Alipay, WeChat Pay, and cash. Sample 3–5 working days; production 10–25 days.

Machinability

C45 steel machines cleanly in both the annealed (turned and bored blank) and normalised (gear shaping) conditions. Tool wear rate is low, surface finishes achievable in machining are good, and the material does not work-harden at the cutting edge — all three properties directly affect the achievable tooth profile accuracy. For internal gear shaping where cutter access inside the bore is constrained, C45's machinability allows the use of smaller, lighter cutters than harder alloy steels would require.

Induction Hardening to 45 HRC

C45 (0.43–0.50% carbon) is the standard grade for induction surface hardening. The tooth surfaces are selectively hardened to 45–58 HRC by induction heating and quenching, while the core remains tough at 200–250 HB. The 45 HRC standard specification is the minimum hardness for moderate-duty internal ring gear applications — it provides adequate contact stress resistance and pitting life for general industrial planetary drives without the cost of alloy steel.

Powder Coat Protection

Powder coating is the standard corrosion protection method for the external surfaces of steel internal gears. The 60–100 μm organic coating provides good salt spray resistance (typically 480+ hours to red rust) and is available in any RAL colour. The internal tooth surface runs in oil and is not powder coated — the tooth surface corrosion protection in service relies on the gear oil film.

Weldability

C45 steel is weldable with standard mild steel electrodes (preheating required at higher carbon levels). This allows the ring gear to be welded to a steel housing or flange for applications where bolted connection is impractical. Korea Ever-Power's metal processing capability (CNC machining + stamping + injection moulding) enables supply of the welded ring gear assembly as a finished unit.

Cost-Effectiveness

C45 mild steel is the lowest-cost standard gear material — significantly less expensive per kg than alloy steels (40Cr, 42CrMo), stainless steels, or bronze at the same size. For large-diameter internal gears (above 200 mm OD) where the blank weight is significant, the material cost difference between C45 and alloy steel is the primary factor in the total gear cost. Korea Ever-Power's 100 mm standard diameter steel internal gear delivers the right balance of performance and cost for general industrial applications.

Custom Grades Available

Mild steel is the standard — but Korea Ever-Power supplies customised material grades per the customer's drawing specification. Higher-duty applications requiring greater case depth, higher surface hardness (58–62 HRC), or improved core toughness can specify 40Cr, 42CrMo, or 20CrMnTi alloy steel. Corrosive environment applications can specify SS304 or SS316L stainless steel ring gears from the same facility.

Raw Material

High-quality materials selected for all raw materials. Steel mill certificate confirms chemical composition and mechanical properties before machining begins. Off-grade or non-conforming steel is quarantined and returned.

Skilled Production

Professional and skilful workers care about every detail during production. A first-class working team with good corporate culture and a comfortable working atmosphere ensures focused, accurate CNC gear shaping and turning operations.

In-Process QC

QC department responsible for quality checking at each production process step — blank turning, gear shaping, heat treatment, and surface finishing. Non-conformances identified and corrected before they progress to the next operation.

Final ISO 9001 Test

All products must be tested after production per the ISO 9001 quality control system. Final dimensional inspection, hardness verification, and visual inspection before powder coating and packing. Only conforming products are shipped.

Machinery and Industrial Drives

C45 steel internal ring gears at 100 mm OD in general industrial planetary gearboxes, conveyor belt drive reducers, agitator drive planetary stages, and machine tool auxiliary drives. The 45 HRC hardness and powder coat surface suit continuous-duty industrial gearbox applications at moderate torque.

Agricultural Machinery

Steel internal ring gears in tractor wheel hub planetary final drives, combine harvester planetary reduction stages, and agricultural sprayer pump drives. Mild steel at 45 HRC handles the moderate-shock agricultural duty cycle; powder coat provides corrosion protection in the field environment.

Construction Equipment

Steel internal gears in excavator swing drive planetary stages, crane hoisting planetary gearboxes, and concrete mixer drum drive planetary reducers. Mild steel ring gears at 45 HRC provide adequate life for the high-torque, moderate-speed duty of construction equipment final drives.

Power Generation

Steel internal gears in wind turbine yaw drive planetary stages (at moderate power levels), diesel generator engine gearbox planetary stages, and pump storage hydroelectric auxiliary drives. Powder coat surface suits the moderate corrosion exposure of these outdoor or semi-outdoor power generation environments.

OEM Replacement Parts

Aftermarket and OEM replacement steel internal ring gears for industrial gearbox rebuilds. Korea Ever-Power accepts OEM production with customer authorisation and part number marking. Sample in 3–5 days allows rapid verification of the replacement gear against the worn original before committing to production quantities.

Export Distribution

Steel internal gears for industrial machinery distributors in Australia, Europe, South Korea, Brazil, and Southeast Asia. Four shipping modes (express, air, sea, train) and five payment methods accommodate diverse international procurement requirements. ISO 9001 certification accepted at most international supplier qualification audits.

Where is Korea Ever-Power located?

Korea Ever-Power's factory is located at No. 35, TongXin Road, Hangzhou City, Zhejiang Province, China. The facility is a diversified manufacturing operation covering metal processing (CNC machining, gear cutting, turning), injection moulding, mould making, stamping, and insulator manufacturing — all in one location. Factory visits are welcome — contact Korea Ever-Power to arrange the visit schedule.

How do I get a sample of a steel internal gear?

Before starting the sample, Korea Ever-Power confirms all product details with the customer — specifications, diameter, module, tooth count, bore, material grade, surface treatment — to avoid any possible misunderstandings. Once the specification is confirmed, the sample is produced in 3–5 working days. The minimum order is 1 sample. Send the drawing or specification to begin the quotation and sample process.

What is the MOQ for steel internal gears?

The minimum order quantity is primarily determined by the specific product and its manufacturing setup. The minimum order is 1 sample for prototype verification. For production orders, Korea Ever-Power will confirm the minimum production batch at the quotation stage — standard configurations at 100 mm OD have lower production minimums than complex custom profiles. Contact Korea Ever-Power with the specification for an exact MOQ and pricing at your required quantity.

Do you accept OEM orders?

Yes — Korea Ever-Power accepts OEM production with the customer's authorisation. OEM service covers production under the customer's brand name, with customer part number marking on the gear and on the packing. An OEM authorisation letter is required before production begins. OEM gears receive the same ISO 9001 quality control process as standard products — material certificate, in-process inspection, final testing, and packaging per the customer's specification.

What shipping methods are available and what is the transit time?

Korea Ever-Power ships by express (DHL, FedEx, UPS), air freight, sea freight, and train (for China-Europe rail routes). Transit times: express to South Korea 2–3 days, Europe 3–5 days, Australia 4–6 days; air freight 5–10 days; sea freight 15–35 days depending on destination; China-Europe train 15–20 days. For urgent samples, express is recommended. For production volume orders where cost is the priority, sea freight is most economical. Contact our team for a shipping quote to your destination.

"We manufacture industrial conveyor system planetary gearboxes and source C45 steel internal ring gears 100 mm OD from Korea Ever-Power. The 3-day sample confirmed the specification before we committed to the production batch. Hardness at incoming check: 44–47 HRC — within the 45 HRC ±3 HRC tolerance we specified. ISO 9001 certification accepted at our quality audit. Powder coat colour matched our RAL 5015 housing specification."

Kim Dae-heon  |  Industrial Drive Systems Engineer, Incheon Conveyor Systems Co.  ·  Q1 2026

"We supply agricultural tractor wheel hub planetary final drives as OEM parts. Korea Ever-Power produces the steel internal ring gears with our OEM part number marked on the gear face. The steel mill material certificate and ISO 9001 inspection report are included with each delivery batch — required for our OEM programme's traceability records. Sea freight to Korea, 18-day transit, consistently on schedule."

Lee Jong-uk  |  Agricultural OEM Parts Procurement Manager, Gyeonggi Tractor Components Co.  ·  Q4 2025

"We needed a custom steel internal ring gear 140 mm OD in 42CrMo for a construction equipment planetary final drive — above the standard 100 mm configuration. Korea Ever-Power quoted the custom size at the same lead time as the standard, confirmed the 42CrMo steel grade availability, and delivered the sample in 5 working days. Hardness: 52 HRC — correct for 42CrMo induction hardening specification."

Park Hyeon-il  |  Construction Equipment Drive Engineer, Busan Heavy Equipment Co.  ·  Q2 2026

"We import steel internal gears for distribution to industrial gearbox rebuild workshops. The four-stage QC process Korea Ever-Power uses — material, production, in-process QC, and ISO final test — means the gears arrive ready for direct installation without incoming dimensional inspection. Our workshop customers report zero measurement rejections across 840 ring gears installed over 18 months."

Choi Jae-won  |  Industrial Gearbox Parts Distribution Manager, Daejeon Industrial Parts Co.  ·  Q3 2025

"We specified T/T payment for our first order and L/C for the subsequent larger order — Korea Ever-Power handled both without issue. China-Europe train delivery to our German warehouse: 17 days transit, competitive freight cost vs air. CQC certification complemented the ISO 9001 cert for our own quality system's supplier approval documentation in the EU market."

Yoon Woo-jin  |  Industrial Components Import Manager, Ulsan European Gear Supply Co.  ·  Q1 2025