Improving the quality of spur and helical gears is critical in production, and there are many methods to accomplish that. Rotary gear shaving and roll-finishing are done in the green or soft state prior to heat treatment. These processes have the ability to modify the gear geometry in order to compensate for the distortions that occur during heat treatment.
Gear honing is a particularly effective method of removing nicks and burrs from the active profiles of the teeth after heat treatment. Combined with its ability to improve surface finish and make minor form corrections, the honing process is rapidly being accepted as a technique for surface finishing of gears after the heat treatment process.
Benefits of gear honing gear honing:
- Corrects dimensional errors
- Corrects distortions caused by heat treatment
- Removes nicks caused by handling
- Improves surface finishing
Gear honing is characterized by leaving fine grinding marks due to grinding at an angle. Grinding uses a gear honing wheel in the shape of an internal-tooth gear that meshes with the workpiece to grind the tooth surface. While it is a form of grinding in a way, as it uses a gear honing wheel, it is called “honing” to differentiate it from the normal grinding process. Typical surface finishes for ground tooth surfaces are in the range of 0.8 to 1.6 micron CLA (32 to 63 microinch). Honing is done to improve the surface finish to the 0.4 to 0.8 micron CLA (16 to 32 microinch) range.
Increasingly, most gears used in high-load applications are miniaturizing to save weight and space. Improving the surface finish and dimensional accuracy of the gear teeth and bore allow for smaller, more lightweight gears to carry the same load as a lower quality, larger design.
In many of the gear manufacturing shops, grinding is the final processing step for both faces and bores. This post is an effort to expose manufacturing engineers (especially in shops specializing in small and medium production runs) to the idea of cup wheel finishing and honing technology as a potential alternative to grinding.
Economically, gear honing has become an essential part in the production of high-speed transmissions. Gears that have been honed instead of ground offer excellent wear characteristics and are extremely quiet.
Although gear honing is a universal technology, it is mostly used in automotive, aerospace, truck, and heavy equipment industries. This method is suitable for any application where quiet, robust, and reliable gearing is required. As hybrid and electric technology has evolved in the automotive industry, gear noise has become an issue to be addressed. In gears developed using the honing process, engine noise is greatly reduced and people will not be able to hear any gear noise. OEMs are becoming aware of this and have increased the use of noise-eliminating gear honing in these applications. Additionally, in applications such as heavy truck transmissions, where robustness and durability are necessary, honing is the preferred method of gear finishing.
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