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Thread: Avoiding Retapping at Assembly line

  1. #1
    Associate Engineer
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    Avoiding Retapping at Assembly line

    In heavy machinery parts we often use M10~M42 taps in various components and they are kept in queue in paint shop, cr plating shops or in stores for weeks.

    When we try to assemble the same in assembly bolts are not entering
    causes:
    1) Dust and other particles inside.
    2) Cleaning is tough in tapped holes

    Effect :
    1) Retapping - leading to oversize of threads,
    2) Assembly time lost.

    Options tried:
    1) Plastic plugs - Costly (equal to steel plugs- when bought in low volumes)
    2) Steel plugs (if not properly stored threads get damaged and spoils thread in next jobs)

    Do we have any good solution to avoid this NVA.

  2. #2
    Administrator Kelly Bramble's Avatar
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    So, compressed air is not enough to clean the dust and other particle from the threaded features? Also, why would a re-tap be required for dust and particles? A thread chaser will remove particles yet not change the thread itself.

    There are many options of thread protectors available in industry. The math is simple..

    Costs associated with a thread protector vs thread chaser and cleaning holes.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
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    Quote Originally Posted by Kelly Bramble View Post
    So, compressed air is not enough to clean the dust and other particle from the threaded features? Also, why would a re-tap be required for dust and particles? A thread chaser will remove particles yet not change the thread itself.

    There are many options of thread protectors available in industry. The math is simple..

    Costs associated with a thread protector vs thread chaser and cleaning holes.
    Hi thanks!!
    We clean with compressed air. still we face problem while entering the bolts.
    1) Bolt not entering the initial threads - So we normally retap.
    2) But we check these threads after machining using gauge and found ok -> after subjecuting process like Cr plating and painting we get this issue.

    The threaded holes have chamfer also so no possibility of thread entry gets damaged during transit or handling.
    Do we have thread chasers for M42 sizes.

  4. #4
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by Ganny View Post
    2) But we check these threads after machining using gauge and found ok -> after subjecuting process like Cr plating and painting we get this issue.
    I would take a hard look at the masking/thread caps being used during plating and painting. Cr and paint buildup should be prevented. You need to spend the money on good thread protection to save the costs associated with retapping.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  5. #5
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    Kelly is right. Any material on the threads will create a problem. Another solution might be to cut threads after coatings have been applied.

  6. #6
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    Is there any tool for truncating small ID threads !

    Quote Originally Posted by Georgefam View Post
    Kelly is right. Any material on the threads will create a problem. Another solution might be to cut threads after coatings have been applied.
    Do we have any possibility and tool to truncate the internal threads weak starting threads.

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