By retooling all milling operations on the line, especially the overheated straddle milling step, USM has more than tripled edge life and pocketed more than $200,000 a year in machining cost savings.
The longer ear requires milling on both sides, thus the difficult straddle milling operation.
"In straddle milling narrow unsupported sections like these yoke ears, there are several problems to overcome besides the heat," says Ingersoll's Tilton.
The old cutters used zero-rake, square, fiat, coated carbide inserts, four edges per insert and the straddle milling operation required very heavy cuts.
The new straddle milling cutters, 8 1/2" and 9" effective diameter respectively, have a finer pitch than before.
Arbor changeout time runs about ten minutes for the one-side milling operation and 15 to 20 minutes for straddle milling. Toolsetting time, done off line, runs about the same as before even though the new cutters have twice as many inserts each.