Master Gears

Master Gear Design

Working of Master Gears

Manufacturing Master Gears

Master gears are primarily used for checking the accuracy of work gears. Work gears and master gears are generally rolled together on a rolling fixture. The centers may be either fixed or adjustable. The dimensional variations may then be precisely ascertained. This is done by using indicators, charts, or other proper indicating devices. Master gears are used for the following types of gears.

• Spur Gears (with/without profile and flank corrections)
• Helical gears (with/without profile and flank corrections)
• Internal Gears

Master Gear Design
Some of the standard Master Gear Blanks are shown here. Master Gears are specifically designed to check the individual components. Further, using one master gear for several other components is also possible. In the image size 1 is recommended for use in fine pitch (20 DP and finer). While Size 2 - 5 is recommended for use in coarse pitch (20 DP and coarser)

Working of Master Gears
As already stated the main function for which the Master gears are used is for checking work gears. The Master Gear flank checks the work parts by rotating in contact with the work gear teeth. It primarily checks the following. Meshing, run out and centre distance, detection of nicks etc. Two master gears of varied design an for different applications can inspect the same workpiece correctly. To give an illustration, two master gears with different limitations with respect to centre distance may show different profile deviations, but can correctly check the entire active profile of the work gear teeth.

Manufacturing Master Gears
Though Master Gears can be made from a variety of materials. Good option is the high speed steel or bearing steel. However the type of steel to be used depends on the individual needs and requirements. Other option are normal and hardened tool steel typically for shorter production runs. For increasing resistance against wear and corrosion, specialist coatings can also be applied by the sophisticated process of chemical vapour disposition.

The Master Gears are produced according to applications. For example Master Gears that checks collision-type deformation can be manufactured to the specification of DIN 3962 class 5. Master Gears used for checking meshing quality can be specified to DIN 3962 class 3-4 while setting masters are manufactures to DIN 3962 class 3.

The following table shows through illustrations, the manufacturing process of Master Gears