Threading Issue heat treated 4140 with Fanuc 10t control
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    Jun 2011
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    Default Threading Issue heat treated 4140 with Fanuc 10t control

    Running some 1.25-7 double end studs and am having some trouble getting a quality surface finish on the thread, although they do gage 2A just fine.
    It looks as though the material is ripping instead of cutting.
    Using some full-profile 7 pitch inserts from ToolFlo. I got the cutting data of .0213 depth and 125 SFM.

    1.25" bar about 3" hanging out chuck, no live center.
    the material is ASTM A-193 B7 (4140 heat treated to about 275 BHN/102 HRB)

    After fooling around with the speeds and feeds I ended up going with the suggestion on the website
    so I've been running the G76 cycle at 300 rpm (about 125 SFM) with an initial infeed depth of .0213
    Now, the Fanuc control has 4 options for infeed, the best result I got was with option 4 which is
    constant depth alternating side cutting (this was what the ToolFlo website recommended for superior finish).
    It runs the cycle in about 6-7 passes which makes for HUGE curls (7 pitch)

    Here's my code line:

    Also, I have a second G76 immediately after to clean up.

    Anyways, I can't figure out why the finish is coming out poor. Is my SFM way to high? Not high enough? Is my infeed Depth too much? Is it better do use an infeed option that only uses one side of the tool? do I need to get a center on there?

    I greatly appreciate any help from you guys, this is my first threading job on the CNC lathe and really want to understand what's going on so that I don't develop bad habits. If you need any more info about the cutting data
    just let me know. I don't have the details about the inserts here at home, but I can get that at work tomorrow.


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