Tried plunge roughing on a job last week and it wrecked my insert in under 10 parts

I was running a 304 stainless part at a shop in Cleveland and decided to go against the advice of the more experienced guys, used a 1/2 inch indexable with a 0.05 stepover at 3000 rpm, and the corner chipped out on part 8 because I didn't account for the chip thinning - has anyone else had luck making that work without killing tools?

2 comments

2 Comments

taylor_barnes5910h ago

...and honestly that sounds more like a tool holder or rigidity problem than the technique itself. I've run that exact setup in 304 with a 1/2 inch indexable doing plunge roughing and got over 40 parts before the insert needed flipping. You pushed too hard on the stepover for that rpm, chip thinning kills the edge contact area and concentrates the heat right at the corner. Drop to 0.03 stepover and bump the rpm up to 4000, let the insert actually shear instead of rubbing. The guys who say it can't work probably never dialed in the feed per tooth right.

fiona_nelson517h ago

pushed too hard on the stepover" is the real issue there. People blame the method when they're just running a bad combo of feeds and speeds. That thin chip at higher rpm saves the corner every time.