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IndustryArena Forum > GENERAL MANUFACTURING PROCESSES > MILLING > Slitting 4140 - Work hardened - How to recover
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  1. #1
    Join Date
    Mar 2007

    Slitting 4140 - Work hardened - How to recover


    I'm having trouble slitting 4140. Being a novice, I overheated the cutter by running to fast an rpm and the slot has work hardened. Hack saw skates in slot, rear of slot is discolored. I suspect I need to anneal the piece to get past this but am concerned it might damage the part..

    Any suggestions on how to complete the slot?

    Hand milling on RongFu Mill - traditional hand fed - not climb milling
    Slot 1/6" wide 3/8" deep, 5/16" long in 4140 (Initially non hardened)
    Have about .100" left to cut

    Saw was HSS 3" x 1/6 x 1" arbor no key, 30 teeth - flat tooth, on a china universal size arbor.

    Even though was to fast, It cut fine .020 per pass with a little machine oil coolant till I got to the tooth depth. Started to make some awful noise...etc.

    My current plan is to pickup a few saw blades with key, try to cut through at a very slow feed with an alternate keyed arbor which I have somewhere. If that fails anneal and use one of the spare saws.

    Any suggestions on blades, speeds, etc to complete cut would be greatly appreciated.

  2. #2
    Join Date
    Mar 2007

    Re: Slitting 4140 - Work hardened - How to recover

    Well I was able to finish the slot by hand with a diamond needle file. It appears suitable for now.
    The best suggestion I've found for the saw is 70rpm with a warning for feed calcs that not all teeth are engaged with these saws
    Sorry if I posted in the wrong Forum

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