Spur & Helical Gears

Geyontech high precision ground spur and helical gears. DIN 3 grinding, module M0.5~M20, up to Φ800mm.

Specifications#

Carburized Ground Precision Gears: Specs, Apps, Failure Prevention#

Carburized and ground precision gears are Geyon Transmission’s core product line, used in reducers, excavator slewing drives, wind turbine gearboxes and robot joints. Geyon’s engineering team has 13 years of gear-making experience (company established in 2020). Batch delivery holds DIN/ISO grade 4-5, single pieces reach DIN 3 by grinding, and tooth surface roughness lands at Ra 0.2-0.4 μm. 20CrMnTi parts carburized and hardened reach 58-62 HRC surface hardness, with effective case depth held at 0.5-3.0 mm per GB/T 9450. Every lot is fully checked for pitch, profile and lead before shipping; reports travel with the goods and parameters are traceable.

1. Four Ways Gears Fail, and Most Trace Back to Heat Treatment and Accuracy#

When a gear fails, it fails one of four ways: pitting, tooth breakage, wear, scuffing.

• Pitting: contact fatigue. When surface hardness is low or the case is too shallow, the tooth face develops micropits under cyclic contact stress, and they grow into cavities. Most common in heavily loaded gearboxes.
• Tooth breakage: bending fatigue. Stress concentrates at the tooth root, the core lacks toughness, and the tooth snaps at the base. Common under impact loads — construction and mining equipment are the usual victims.
• Wear: low surface hardness and rough surfaces speed up both abrasive and adhesive wear.
• Scuffing: at high speed and heavy load the oil film breaks, metal touches metal, and the tooth face is torn into grooves.

Pitting and breakage account for most failures, and both tie directly to material, heat treatment and grinding accuracy. A real case: a 20-ton excavator’s slewing drive pinion, originally hobbed to GB grade 7 with 52-55 HRC surface hardness and a 0.6 mm case, pitted after 800-1200 hours of operation. After switching to grinding (GB grade 4 / DIN 5) and holding the case at 0.8-1.2 mm, the slewing system life went from 1,800 hours to over 5,800 hours. Figures are from Geyon’s customer case archive.

The conclusion is plain: whether a gear survives depends on surface hardness, case depth, profile accuracy and surface roughness — hard numbers, not claims.

2. Specifications: Size Range, Materials and Inspection#

Cylindrical gear (spur and helical) machining and inspection envelope:

Materials and heat treatment follow the application:

Before shipping, each lot is checked against the items below in a 20 ± 1 °C temperature-controlled room. Reports travel with the goods:

The full inspection list and equipment are on the gear inspection report page.

3. Where Carburized Ground Gears Are Used#

• Reducer and gearbox makers: planet gears, sun gears and gear shafts. High contact stress on the tooth face makes carburize-plus-grind the standard route.
• Construction machinery: excavator slewing drives and travel reducer gears. Impact loads and frequent start-stop cycles call for protection against breakage and pitting. DIN/ISO 4-5 is the suggested grade.
• Wind turbine gearboxes: planet-stage gears carry most of the transmitted power, with a 20-year design life. Tooth-face fatigue is the key criterion; case depth and flaw detection are held to tight limits.
• Robotics and automation: small-module joint reducer gears (M0.5-2) where backlash and noise matter most.
• High-end equipment OEMs: custom parts per drawing. We review machinability on receipt of the drawing, then propose a solution and price.

4. How We Keep Failures Out Before They Leave the Factory#

1. Material and heat treatment come first. 20CrMnTi is carburized at 920-940 °C, boost carbon potential 1.0-1.2 %C and diffuse 0.8-0.9 %C, for 4-8 hours; quenched at 820-850 °C in hot oil, tempered at 180-200 °C for at least 2 hours. The result is a 58-63 HRC surface over a 30-42 HRC core — hard on the outside, tough inside, each aimed at a specific failure mode. Case depth is measured to GB/T 9450 and printed in the inspection report.

2. Grinding runs in two passes. Carburizing and hardening distort the tooth face, so a rough grind first recovers the distortion, then a finish grind produces final accuracy. Surface roughness lands at Ra 0.2-0.4 μm, and grinding burn is checked by acid etch so grinding heat does not soften the surface layer.

3. Profile modification on demand. Tip relief and lead crowning are calculated in KISSsoft to even out load distribution and cut stress concentration at the tooth ends — a common starting point for breakage and edge pitting. Modification values go on the drawing and are repeated in production.

4. Inspection covers the whole flow. Critical parts are 100% inspected: a gear measuring center checks pitch, profile and lead; hardness testers check surface and core; metallography checks tempered martensite and retained austenite (≤ 20%); magnetic particle and ultrasonic testing look for internal cracks. Outgoing lots are sampled to AQL and reports ship with the goods. All inspection equipment is within calibration. The processes are described on the precision gear grinding and gear customization service pages.

5. Send the Drawing, Get the Quote First#

Reducer makers, OEMs and traders are all welcome to contact us. Send a drawing (PDF, DWG or Solidworks), or simply module, tooth count and accuracy grade — we usually reply with price and lead time within 1-2 working days. Prototype runs and volume production are both fine.

How to inquire: send drawing → technical review → quotation → sampling or production. Email sales@geyontech.com with “carburized gear inquiry” in the subject line. More products are on the product center page.

Manufacturing processes#

• Gear hobbing (accuracy GB class 6~7)
• Gear shaping (internal gears, stepped gears)
• Gear shaving (accuracy GB class 5~6)
• Gear grinding (up to DIN class 3)

Features#

• Stable batch accuracy, GB class 4~5
• Ground teeth up to DIN class 3
• Module range M0.5~M20
• Max. outer diameter Φ800mm

Applications#

• Industrial machinery drive systems
• Precision drives for automation equipment
• Automotive transmission gears
• Power transmission for construction machinery