What is grinding burn?

Local overheating of the gear surface during grinding, which softens or cracks the hardened layer. Correct wheel, coolant and feed avoid it; etch tests reveal it.

Is gear grinding the same as gear honing?

No. Grinding removes the hardening distortion and sets the accuracy. Honing is a lighter finishing step that improves finish and noise.

Which gears need grinding?

Hardened gears for gearboxes, machine tools, high speed or quiet running, usually where quality better than about class 7 is needed.

Gear grinding machine: types, accuracy, uses

A gear grinding machine finishes the teeth of hardened gears with an abrasive wheel. Generating grinders use a threaded wheel that rolls with the gear, much like hobbing; profile grinders use a wheel dressed to the tooth space and grind one gap at a time. Both correct the distortion left by hardening and give high gear quality.

Quick facts

Main types: Generating (threaded wheel), profile (form wheel)
Typical module range: About 0.5–10 on general machines; larger on big profile grinders
Accuracy: About DIN 4–6 / ISO 1328 class 4–6
Wheel dressing: Diamond rolls or dressers on the machine
Gears: Spur and helical; internal on special machines
Checking: On the machine with probes, or on a gear tester

Main parts

Workpiece spindle with a precise indexing (C) axis
Grinding spindle with threaded or form wheel
Dressing unit that keeps the wheel profile true
In-process probe to find the teeth and measure
Coolant (often grinding oil) and filtration
CNC with gear data and flank modifications

Generating or profile machine?

	Generating	Profile
Speed	Fast	Slower
Best for	Batch production, small and medium modules	Large gears, small batches, special profiles
Wheel	Threaded, CBN or vitrified	Form wheel per module

Good to know

Gears are ground from the same datum as they will run on
Tip and root relief and crowning are ground in to make gears quieter
Grinding burn must be avoided; nital etch or Barkhausen tests check for it
Gear testers check profile, lead and pitch against the quality class

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Questions

What is grinding burn?: Local overheating of the gear surface during grinding, which softens or cracks the hardened layer. Correct wheel, coolant and feed avoid it; etch tests reveal it.
Is gear grinding the same as gear honing?: No. Grinding removes the hardening distortion and sets the accuracy. Honing is a lighter finishing step that improves finish and noise.
Which gears need grinding?: Hardened gears for gearboxes, machine tools, high speed or quiet running, usually where quality better than about class 7 is needed.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 22 October 2026.