Steel Spur Gear – C45, M1-M12, OEM Custom, DIN 6-9

Steel spur gears are the most widely used gear type in mechanical power transmission — and the most widely used material for spur gears is steel. The straight involute tooth profile, combined with the strength, hardness, and machinability of steel, produces the most cost-effective gear for the broadest range of industrial, commercial, and precision applications. Korea Ever-Power manufactures customised steel spur gears in C45 carbon steel, alloy steel, stainless steel, brass, copper, aluminium, and POM across module M1 through M12 and larger, to any standard (ISO, DIN, ANSI, JIS, BS, or non-standard), in DIN 6–9 accuracy grades.

Steel spur gear transmission is the primary mechanical transmission mode for parallel shafts, with advantages of large bearing capacity, high accuracy, and constant transmission ratio. It has been widely used across every industry: peripheral speed can reach 300 m/s, transmission power up to 10⁵ kW, and gear diameter ranges from under 1 mm to over 150 m. Korea Ever-Power's OEM manufacturer service covers the full custom production cycle from drawing review through to final inspection and delivery.

Constant Transmission Ratio

The involute tooth profile guarantees a constant velocity ratio between the pinion and wheel throughout the mesh cycle — a property called the law of gearing. This constant ratio property holds even with small variations in centre distance, making steel spur gears forgiving of thermal expansion and shaft deflection in service without the velocity ratio error that would result if the contact law were violated.

Very High Peripheral Speed

Precision-ground steel spur gears at DIN 5–6 accuracy can operate at peripheral speeds up to 20–25 m/s before noise becomes the limiting factor. With careful housing design and tooth profile modification (tip relief), high-accuracy ground steel spur gears in turbine auxiliaries and high-speed compressors can operate at 50+ m/s. At extreme speeds, helical gears are preferred, but for medium-speed drives up to 15–20 m/s, precision steel spur gears are entirely adequate.

High Transmission Power

Gear transmission is the most powerful mechanical transmission type in common use — spur gear pairs in industrial applications regularly transmit 100–5,000 kW of continuous power. The practical power limit of a steel spur gear pair at a given module and face width is set by the tooth surface fatigue (pitting) strength and the tooth root bending fatigue strength, both of which scale with the cube of module and directly with face width and material hardness.

Long Service Life

Steel spur gears operating within their rated load and speed, with adequate lubrication, routinely achieve 20,000–50,000 hours of service life (equivalent to 10–25 years of single-shift industrial operation). Correct material selection, heat treatment to the specified hardness, and accurate tooth profile (DIN 7 or better) are the three requirements for achieving this service life. Korea Ever-Power's production process addresses all three.

Rack and Pinion Compatibility

The straight tooth profile of the spur gear is the natural companion to the linear rack — the rack profile is a straight-sided tooth form (the limiting case of an involute at infinite radius). Korea Ever-Power produces both the spur pinion and the matching steel rack at the same module and pressure angle, ensuring correct backlash and pitch accuracy across the full rack length for CNC machine tool and linear automation applications.

OEM Custom Production

Korea Ever-Power functions as an OEM manufacturer — customer brand name, part number marking, and custom packaging are available. The production facility has been making customised steel spur gears for over ten years with hundreds of qualified personnel. This experience base covers non-standard modules, unconventional bore profiles, face widths outside the standard range, and combined surface treatment sequences for specific customer specifications.

General Industry Machinery

C45 spur gears M2–M8 in speed reducers, conveyors, agitators, fans, blowers, and compressor drives. The widest application range — C45 steel at DIN 8 is the standard specification for general industrial spur gears where no special corrosion or high-temperature requirement exists.

Machine Tools

C45 or 40Cr hardened spur gears M2–M6 DIN 7 in lathe headstocks, milling machine spindle gearboxes, and grinding machine table drives. Machine tools require the sliding gear-shift mechanism that only spur gears can accommodate — a significant application driver that makes spur gears the mandatory choice over helical gears in speed-selectable spindle drives.

Medical Equipment

SS304 or SS316L spur gears M1–M3 DIN 6–7 in surgical robot joint drives, hospital bed positioning systems, and imaging equipment gantry drives. Stainless steel eliminates the corrosion risk in sterilisation environments and meets the non-magnetic requirement for MRI-adjacent drives.

Semiconductor Industry

SS316L or special alloy spur gears M1–M3 DIN 6 in wafer handling robots and cleanroom automation. Zero outgassing, no magnetic interference, and no corrosion in the semiconductor process atmosphere are simultaneous requirements that stainless steel spur gears satisfy.

Parking Systems and Solar Energy

C45 steel spur gears M6–M12 with Dacromet or powder coating in outdoor automated parking system lift drives and solar tracker rack-and-pinion drives. Corrosion protection coating and moderate module suit the intermittent-duty, moderate-load outdoor application.

High-Speed Rail and Aviation

Alloy steel spur gears M4–M12 DIN 6–7 in rail vehicle auxiliary drives and aircraft ground support equipment. Full material traceability, heat treatment certification, and DIN inspection report are standard deliverables for rail and aviation supplier qualification.

What is the rack and pinion transmission and how does it relate to spur gears?

A rack is a linear gear with straight-sided teeth — the limiting case of a spur gear with an infinite pitch circle radius. When a spur pinion meshes with a rack, the rotary motion of the pinion is converted to linear motion of the rack (or vice versa). The linear travel per pinion revolution equals module × tooth count × π. Rack-and-pinion transmission is used in CNC machine tool table drives, linear actuators, gate operators, and steering systems. Korea Ever-Power produces the matching spur pinion and steel rack at the same module and pressure angle — ensuring correct backlash and contact across the full rack length.

What tooth profile angle do Korea Ever-Power steel spur gears use?

Standard steel spur gears use a 20° pressure angle — the ISO/DIN/JIS standard. Since the rack tooth profile is straight, each point on the rack tooth profile has the same pressure angle equal to the inclination angle of the tooth profile: 20° for standard full-depth teeth. The 14.5° pressure angle standard (older AGMA and JIS standard) is also available for replacement or legacy system applications. The 20° standard provides higher tooth root thickness and load capacity than 14.5° at the same module, which is why it replaced 14.5° as the world standard.

Can Korea Ever-Power produce steel spur gears from customer samples without drawings?

Yes — Korea Ever-Power measures the customer sample and produces the drawing for approval before production. Required measurements for a steel spur gear are: outer diameter (OD = (z + 2) × m), root diameter, face width, bore diameter, keyway dimensions, tooth count, and any hub dimensions. The module is calculated as OD / (z + 2). Send the sample and Korea Ever-Power will confirm the module and drawing within the agreed lead time. For samples from multiple national standards (AGMA, JIS, DIN), the same measurement process applies regardless of the standard of origin.

How do I get a quotation as quickly as possible?

Korea Ever-Power quotes within 24 hours of receiving an enquiry for standard configurations. If you need an urgent quotation, state this at the start of the enquiry and we will treat it as priority. To receive the fastest quotation, provide: module, tooth count, bore diameter, face width, material, heat treatment, surface treatment, accuracy grade, quantity, and delivery requirement. If a drawing is available, send it directly — a complete drawing eliminates the back-and-forth on dimension confirmation and is the fastest path to a correct quotation and production schedule.

What surface treatment is recommended for steel spur gears in outdoor or humid environments?

For outdoor applications (parking systems, solar trackers, agricultural machinery), Dacromet or Geomet coating is recommended: water-based inorganic zinc flake coatings that achieve 480–1,000+ hours salt spray resistance without hydrogen embrittlement risk (critical for hardened steel gears, where conventional electroplating can induce hydrogen embrittlement). For indoor humid environments, zinc-plated + clear chromate passivation (8–12 μm zinc) provides adequate protection at lower cost. For severely corrosive chemical environments, stainless steel is recommended over surface-treated carbon steel — coating integrity cannot be guaranteed at tooth flanks subject to wear. Contact our team with the specific environment for a surface treatment recommendation.

"We manufacture CNC router rack-and-pinion drives and source M4 C45 spur pinions from Korea Ever-Power to match our standard module M4 racks. The pitch accuracy across the pinion was confirmed at DIN 7 on our gear measurement machine. 24-hour quotation response from drawing submission. Two years of continuous production supply with no quality rejection."

<pstyle="margin:0; font-size:clamp(13px,1.8vw+8px,15px);">Kim Jong-hyeon  |  CNC Drive Systems Engineer, Incheon Machine Tool Co.  ·  Q1 2026

"We supply SS316L steel spur gears M2 DIN 6 for medical imaging equipment drives. Korea Ever-Power produced to our drawing with non-magnetic confirmation (Feritscope ≤ 2 Ferite number) and surface finish Ra 0.4 on the tooth flanks. 24-hour quotation confirmed; sample within 20 business days. Each gear individually bagged with our part number on the label."

Lee Hye-jin  |  Medical Equipment Component Buyer, Seoul Medical Systems Co.  ·  Q4 2025

"We import M3 C45 steel spur gears in bulk for distribution to general machinery builders in South Korea. Korea Ever-Power's DIN 8 tolerance is confirmed by the dimensional inspection report included with each batch. Black oxide surface treatment specified — corrosion protection adequate for our customers' indoor industrial environment. L/C payment accepted with no issues over 3 years of orders."

Park Sang-uk  |  Mechanical Parts Import Manager, Busan Industrial Distribution Co.  ·  Q2 2026

"We needed M5 42CrMo spur gears induction hardened to 52 HRC for a machine tool headstock. Korea Ever-Power confirmed the steel grade, heat treatment specification, and DIN 7 accuracy from our drawing within 24 hours. Hardness test report confirmed 51–54 HRC across all teeth at our incoming check. Dimensional inspection report within DIN 7 tolerance on all gears in the batch."

Choi Jin-seok  |  Machine Tool Design Engineer, Gyeonggi Precision Machine Co.  ·  Q3 2025

"We design solar tracker azimuth drives and use Korea Ever-Power M8 C45 steel spur pinions with Dacromet coating. Four years of outdoor operation in coastal salt air — no coating failure, no corrosion at the tooth flanks or bore. Dacromet was more cost-effective than stainless steel at this module and gave equivalent corrosion performance in our accelerated salt spray test."

Yoon Cheol-min  |  Solar Tracker Drive Engineer, Daejeon Renewable Energy Systems  ·  Q1 2025