All machines Machines Large Gear Grinding and Hobbing
Precision
Large Gear Grinding and Hobbing
4:16 A gear hobbing machine cutting a very large gear. Filmed and published by Liebherr. Plays from YouTube, nothing here is re-hosted.
What it does
Gears are how torque changes speed and direction, and a gear is only as good as the shape of its tooth flank. Gear machines cut and then grind those flanks to a form accurate enough that the gear runs quietly, shares load evenly across the face, and survives decades under reversing loads.
How it works
Hobbing is a generating process. A hob, which is essentially a worm-shaped cutter with rows of cutting teeth, rotates in a fixed ratio with the gear blank. Neither part has the shape of a gear tooth; the tooth appears because of the relationship between the two rotations, which is why one hob can cut any number of teeth of the same module. After hobbing the gear is usually heat treated, and heat treatment distorts it. Grinding then restores the geometry: a profile grinding wheel dressed to the exact tooth form, or a threaded grinding wheel used in a generating motion, removes a few hundredths of a millimetre and brings profile, lead and pitch back into tolerance. Bevel gears, which carry torque around a corner, need dedicated machines because their flank geometry is a spiral on a cone rather than a shape on a cylinder.
The numbers
Large gear machines handle workpieces measured in meters. Ground gears are routinely held to DIN or AGMA quality grades where the allowable profile deviation is a few microns. Polish grinding as a final step improves the surface finish enough to measurably change friction losses and pitting life in the finished gearbox.
Who uses one
Wind turbine gearbox makers, mining and cement mill drive builders, marine and rail gearbox plants, aerospace transmission suppliers and heavy vehicle drivetrain manufacturers.
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Looking for one of these?
Gear hobbers, shapers, grinders and heavy machine tools. APE sources, buys and sells them. Start a request.
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