L. Midla, Low Country Heat Treat, North Charleston, SC
Dimensional change in carburized gears is inherent in the thermal expansion, contraction, and microstructual transformation that is part of the process. When non symmentrical shapes are involved these normal dimensional changes can be undesirable because the dimensional changes are not symmetrical and are described as distortion.
As large OEM, original equipment manufacturers, outsource component manufacturing and heat treatment, the historic knowledge of the distortion and the manufacturing methods to minimize the impact on the specified gear dimensions can be lost.
This paper will present empirical data on several common non symmetrical shapes that will relate before and after carburized results:
- The actual dimensional changes the gear
- Effects of the gross dimensional changes on gear tooth specifications such as lead error.
- Changes in the machining and heat treatment process that can minimize the impact of these dimensional changes.
Summary: Dimensional change in carburized gears is inherent in the thermal expansion, contraction, and microstructual transformation that is part of the process. When non symmentrical shapes are involved these normal dimensional changes can be undesirable because the dimensional changes are not symmetrical and are described as distortion. Emperical data on several common non symmetrical shapes provides directional data on changes in the gear manufacturing and heat treatment process that can minimize the undesirable impact of the dimensional changes. Both directional and quantitative data can be helpful to gear designers, process engineers, and commercial heat treaters.
