material transfer guide bushings
Problem Description Material transfer on guide bushings happens when workpiece material bonds to the carbide bearing surface during deep hole drilling. I’ve seen this most often when running 304 stainless steel and Inconel at spindle speeds above 4,000 RPM. The transfer builds up progressively, scoring the bushing bore and eventually marking the drill shank. Once the transfer exceeds 0.05 mm in height, it creates a hot spot that accelerates further adhesion. The bushing clearance closes up and the drill starts to bind. I’ve had jobs where a single bushing went from clean to scrap in under 200 parts because I didn’t catch the early signs. ...