Talked to a 30 year machinist and it made me rethink my speeds and feeds

I was complaining to this old timer at the shop about how my inserts kept chipping on a stainless job. He just looked at me and said 'you're running scared, run it harder.' I always thought slower speeds meant safer cuts but he showed me his setup running at 350 SFM with a .012 IPT feed on 304. Tried his numbers on a test part today and the finish was way better with no chipping. Made me realize I've been babying my tools for no reason the last 2 years. Anyone else get told they're too careful with their parameters?

2 comments

2 Comments

the_emma5h ago

Whoa hold on, I gotta push back on this a little. I've seen guys try that "crank it up" approach and end up with a cracked insert that flew across the shop and nearly took out the coolant line. There's a fine line between running hard and just being reckless with your tooling. A slower feed with a lighter depth of cut might not be the fastest way, but it gives you way more room to catch a problem before it turns into a broken part or a scrapped job. Sometimes being "too careful" is just being smart about not losing a whole shift to a crash.

wendy_carr9h ago

Yeah the whole "running scared" thing hit home. My buddy at a job shop, he was always swapping out carbide every ten parts. Creeping way under recommended speeds. Then this older programmer watched him one day and just laughed. Said he was treating the machine like it was made of glass. Told him to bump the feed up by 40% and see what happens. My buddy argued back, said it would break the tool instantly. First part came out fine, second part great, third part he had to stop because the noise was different. It was cutting better, not worse. He called me that night, blown away.