Rack gears used for rack and pinion assembly are often hardened to increase durability. In most cases a finish grinding process is necessary for correcting the distortion of racks after heat treatment. If the hardened gear racks are finished by milling instead of grinding it will increase productivity and cut production costs considerably.
The major benefits of a ground rack are long life, low noise, and low dusting, but grinding machines are expensive and the process, as well as the dressing process, takes considerable time. Also, the high running costs—the actual cost of grinding and dressing wheels, and the electrical costs for coolant and a temperature-controlled room—raise the price of ground racks. Ground racks therefore become much more expensive than hard-cut gear racks.
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