screw striping
screw striping
(OP)
hi everybody
in our assemble line we have a problem. we use a M6 screw with a grade of T7. the screw must pass 3 steel sheets.unfortunately the holes in these 3 sheets are not concentric and that causes the screw to get striped or fractured while fastening with screwdriver. for the time being it is impossible for us to modify the sheet molds and the place of holes. is there any way that with changing the design or heat treatment of screw i can prevent stripping?
best regards
in our assemble line we have a problem. we use a M6 screw with a grade of T7. the screw must pass 3 steel sheets.unfortunately the holes in these 3 sheets are not concentric and that causes the screw to get striped or fractured while fastening with screwdriver. for the time being it is impossible for us to modify the sheet molds and the place of holes. is there any way that with changing the design or heat treatment of screw i can prevent stripping?
best regards





RE: screw striping
Good thing you didn't post in the GD&T forum; those boys would have a really good laugh at your expense.
You can end up with a screw-like object in the finished assembly by filling the holes with epoxy, and finishing off with a stubby screw or just a head where you need a head showing. It won't have any strength, and you can't disassemble it, but it doesn't sound like serviceability matters much to your outfit anyway.
If you did need strength, you could match-drill the holes and use a drive rivet.
Or you could buy some special screws with reduced diameter shanks and a very short threaded point. Forget resisting shear loads with them.
I'm assuming you were forced to ask the question by an ogre boss. Been there.
Mike Halloran
Pembroke Pines, FL, USA
RE: screw striping
you hit it right on the head about my boss.in fact the issue is not that simple. the screw is fastened with a welded nut but the problem is that at that point the screw has no threads anymore.i need the screw to act as a dill and can penetrate the sheet metals without being striped.i know that kind of question is laughing and stupid but that 's my problem.
anyway thanks for your reply
RE: screw striping
What is grade T7?
You could try a Taptite fastener with an induction hardened tip and an unthreaded weld nut. The induction hardened tip would create its own threads through the assembly and in the nut.
RE: screw striping
http://www.mcmaster.com/#tapping-screws/=9or7j7
BTW what is this for? Something we would ever buy for personal use or come in contact with?
RE: screw striping
This type of condition was commonplace for automotive structures (non-critical attachments) up through the 1990's.
RE: screw striping