I found out the real cost of a bad collet while running a job on our old Haas

I was finishing up a run of 500 aluminum brackets yesterday and noticed a weird finish on the last 50 pieces. Took me a while to figure it out, but I pulled the tool and the collet had a tiny bit of gunk in the taper. Cleaned it out and the finish went back to perfect. Got curious and looked up what that kind of rework would cost if it was a full batch of scrap. Saw a post on Practical Machinist where a guy said a single bad collet cost his shop over $8,000 in material and machine time on a titanium aerospace part. That blew my mind. I always check tools, but I guess I got lazy on the collets because they seem so simple. Now I'm putting a note on the board to clean and check them every tool change. Has anyone else had a small part like a collet cause a huge mess?

3 comments

3 Comments

betty_white392mo ago

That "tiny bit of gunk" line is the whole story right there. It's always the simple stuff that gets you. I lost a whole run of delrin spacers once from a collet I thought was fine.

craig.tessa2mo ago

But come on, a whole run of parts lost over some gunk? That seems a bit much. Delrin is pretty forgiving stuff. A tiny bit of buildup might throw off a cut by a few thou, but it shouldn't scrap everything. Maybe the collet had a bigger problem, or the setup was off from the start. Blaming just a little dirt feels like an easy excuse, lmao.

nelson.cameron1mo ago

Dirt in the taper acts like a wedge and changes the runout way more than you'd think. A few tenths at the holder turns into mils at the tip on a long tool. Cheap insurance to just wipe the taper clean every time you swap tools.