Big Machining for a Big Gear

Here’s an example in which MAG demonstrates it knows how to use machine tools as well as build them.


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I’m well aware of the large-scale machining capability that MAG offers. I write about one shop doing big work with one of its G&L machine horizontal boring mills in this article.
But here’s an example in which MAG demonstrates that it knows how to use machine tools as well as build them. It created a machining process using an HBM and special cutters to create 588 teeth in the 62.5-feet-diameter gear assembly shown below.
The 60-ton, two-piece gear assembly (made of ASTM A290 steel) consists of a 24-section track that serves as the base and a 12-section upper gear rack. The MAG team designed dedicated fixtures for each operation and special tooling for cutting and finishing the gear teeth on an HBM. In most cases, the tooth involute profile would be generated by the machine itself, notes Mark Huhn, project manager at MAG Fond du Lac. However, he points out that they used a tool with the form of the involute tooth ground into a cutter.
The gear teeth were manufactured to American Gear Manufacturers Association Gear Quality No. 6, and the gear was assembled to a pitch diameter concentricity of 0.031 inch. The track also required a special cutter to produce a 2.127-degree surface angle. That angle was created on one of MAG’s gantry-type machines via circular interpolation.