3M Gear Grinding Application Guide

Gear Grinding. At the highest level.

As a machine element, the gear wheel is an elementary component of almost all modern machines.

This "wheel equipped with teeth evenly distributed along the circumference" is primarily installed in all types of gearboxes and is needed to make transfers between two rotations or between one rotation and a linear movement (pairing of a gear wheel with a rack). Gear drives represent the largest group among gear boxes. They are positive-locking and are consequently slip-free.

Gear grinding requires high precision throughout the process, and it is important to use the right grinding wheel for the application. The selection of abrasive material and wheel configuration depends on the base alloy, tooth geometry, and size of the production run, among other factors. 3M's recently expanded abrasives portfolio can help you meet the growing demand for tighter dimensional tolerances and shorter production schedules, even with difficult-to-grind materials.

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A solution for every application.

Threaded gear grinding

In threaded gear grinding a number of motions occur simultaneously. The worm grinding wheel rotates on its axis while meshing with the gear workpiece which is rotating on its axis. The radial infeed to engage the gear being ground with the wheel is in the x direction. The infeed across the thickness of the gear is up and down in the z direction while the shift travel moves the gear across the full width of the worm wheel in the y direction.

Diagram Description: A diagram illustrating threaded gear grinding shows a grinding worm and a workpiece. Arrows indicate the grinding stroke (axial feed rate) in the z direction, shift travel in the y direction, and infeed in the x direction.

Bevel gear grinding

In bevel gear machining one distinguishes between two types of grinding:

• Generation grinding (discontinuous)

Generation grinding in bevel gear machining is a discontinuous grinding process in which machining is done tooth by tooth. The generating movement of grinding wheel and workpiece is coupled. Infeed is done through the grinding wheel before entering the flank. During generation grinding all axes are moved; however, the grinding wheel is not infed in the sense of grinding stock.

Diagram Description: An image shows a close-up of a blue grinding wheel engaging with a gear component.

• Plunge grinding

Diagram Description: A diagram illustrates plunge grinding. It shows a grinding wheel and a workpiece with labels for grinding spindle axis, eccentric spindle axis, cutting travel, infeed travel, and eccentric travel.

Plunge grinding is also a discontinuous grinding process, in which machining is performed tooth by tooth. Both tooth flanks are machined simultaneously. There is a surface contact between tooth flank and grinding wheel. Due to the plunge movement of the grinding wheel in the axis direction, the grit path runs in parallel to the tooth base and the surface structure runs in the tooth width direction. Grinding grooves running in parallel to the tooth base emerge. The grinding direction is from the ring gear toe at the inner diameter to the ring gear heel at the outer diameter, or vice versa. Only ring gears can be produced by means of plunge grinding. Pinions cannot be ground with this process due to their geometry.

• Additional oscillating movement besides main rotation of the grinding wheel
• Grinding spindle is positioned in an eccentric bushing, separately driven
• Eccentric value between 0.1 mm and 0.3 mm
• Eccentric speed approx. 200 – 500/min; slower than the rotational speed of the grinding wheel (value approx. 2,000/min)
• Improved surface in pinion grinding

When grinding ring gears, the oscillation causes an interruption of the grinding contact, which means better cooling, lower power consumption.

• Single rib gear grinding

Gear profile grinding is a discontinuous grinding process. Contrary to generation grinding, profile grinding is machined gap by gap. The grinding wheel profile is absolutely identical with the finished gear profile. Compared to generation grinding, where the profile is "produced” by the generating movement, in profile grinding the profile is generated by the profile form that is integrated in the grinding wheel. Thus a higher profile accuracy can be achieved compared to generation grinding.

Diagram Description: A diagram shows a grinding wheel with a specific profile moving downwards onto a gear tooth, indicating profile grinding.

Gear Grinding Product Selection

Typical workpieces

Planet gears

Diagram Description: An image displays three interconnected planet gears of varying sizes.

Cylindrical gears

Diagram Description: An image shows two cylindrical gears, one larger than the other, meshed together.

Bevel pinion gears

Diagram Description: An image shows a single bevel pinion gear.

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