Nerdlinger
Stainless
- Joined
- Aug 10, 2013
- Location
- Chicago, IL
So there's this part we turn, face drill with axial-facing live tooling and cut off in a Hardinge T42. We spec 3/4" round cold drawn annealed 4340. All is well. From time to time we get ground material in...probably just because thats all the supplier had in stock. Then my operators claim when we get the "shiny" material none of the tooling holds up. I thought they were crazy and making up stuff in their mind just because the OD of the material looked "different", but sure enough the drill and cut-off go to shit very quickly...the drill is the worst - like less than 10 parts (.140" X .5" deep hole). We use a general purpose Guhring 730 series drill (150SFM, .003IRP). We tried going both ways on the speed and feed but no dice, so we put in a high speed drill, slow it down and it works okay. This has happened several times over the past couple years - "cold drawn" (i.e. gray) finish = good, "ground" (i.e shiny) finish = bad.
I got my hands on the chemistry report and attached it. Does anyone see anything out of the ordinary that would make the material unusually "tough" that I can maybe try to spec out moving forward?
Thank you!
I got my hands on the chemistry report and attached it. Does anyone see anything out of the ordinary that would make the material unusually "tough" that I can maybe try to spec out moving forward?
Thank you!