Feb 28, 2017 | Tool Time
Not all hobs are created equal. Many hobs must be designed before production, and gear manufacturers who seek the most from their cutting tools choose suppliers that not only design but also engineer their hobs. An engineered hob considers the entire hobbing...
Nov 10, 2016 | Processes
An introduction to the hard finishing of gears. In Part 1 of the Hard Finishing of Gears, we introduced the concept and a brief history of processes used to achieve non-hardened finished parts. Continuing, consider a gear that has been pre- or semi-finished, meaning...
Jun 22, 2016 | Processes
An introduction to the hard finishing of gears. Generally, many “hardened” gears in the United States before the 1970s were a through-hardened part, but this changed to contemporary case-hardening processes that were considered relatively new technology at the time....
Jan 14, 2016 | Tool Time
An introduction to coatings and their use for gear cutting tools. In this issue, we will discuss one of the most important aspects of gear cutting tools aside from the tool itself: tool coatings. The most common process through which coatings adhere to...
Dec 18, 2015 | Tool Time
The effects and causes of hob flute lead error. In previous issues, we looked at several types of hob errors: flute spacing error, rake error, and runout. Another important type of error can be found in the lead of the flute, also known as the gash. Flute lead error...
Nov 9, 2015 | News
A look at the first K160 Repowered CNC gear hobbing machine Koepfer America has completed the next step in its K-Repowered CNC re-control program with the first K160 Repowered CNC Gear Hobbing Machine, which was displayed at Gear Expo 2015 in Detroit, MI. New,...
Sep 29, 2015 | Processes
The benefits and use of automation during the hobbing process. For this discussion, we will categorize parts into three groups: large, medium, and small. Large parts above 400 mm (~16 in) are typically not automated. As a general rule, parts that are 200–400 mm (~8–16...
Jun 4, 2015 | Tool Time
A detailed look at gear tool resharpening. In Issue 13, we discussed the importance of tool quality and the proper maintenance of a tool that shows signs of wear. In this issue, we will cover the basics of the process used to sharpen the hob. The types of wear on a...
Apr 15, 2015 | Tech Tips
Hobs mounted without precision. Consider the following two gear tooth profile inspection charts (these have been simplified for illustrative purposes from what one would see in practice): Inspection charts such as these plot the geometric variance normal...
Mar 17, 2015 | Tool Time
The importance of tool quality. The achievable quality of a gear is greatly affected by the quality of the cutting tool used. “Quality” in this context means geometric accuracy (as opposed to metallurgical quality or surface finish, for example). A gear’s geometry can...
