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Use of 1.5 Sigma Shift and 3.4 PPM

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  • #183625

    Kaare
    Participant

    You are of course free to have your opinion.
    If it makes any diffrence it was M3.5 Stainless steel taptite screws. inserted in a die-cast aluminium housing. The reason for choosing Stainless was that they had to be non magnetic. M3.5 was choosen over M3 in order to build margin on the tourqe. The optimization was done on the geometry of the inserts that are placed in the mould (for the screw holes).

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    #183630

    Taylor
    Participant

    Ever heard of roll thread tapping?
    Makes your problem go away
     

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    #183645

    Kaare
    Participant

    Yes, a very nice technology, I believe this was what taptite used as well…To my knowledge most press-fit parts are produced that way as well (we used quite a few of these as well).
    The major part of our problem was actually wear on the inserts in the mould, causing the screw-holes to narrow over time, and hence reducing the effective presure the screw-head exhibited on the lid. (the torque of the screw robot was constant). By changing the geometry of the insert, we where able to reduce the influence of wear to the required torque of the screws.
    The other part of the problem where screw heads that broke off during insertion.

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Viewing 3 posts - 201 through 203 (of 203 total)

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