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Thread cutting or forming screw for ABS?

Question asked by Andrew Castelino on Sep 22, 2012
Latest reply on Oct 22, 2012 by Lenny Bucholz



Any one have an idea on how to connect ABS plastic shell with a motor made of motor?


Manufacturers told me that their maximum thickness of ABS plasic shell usually not exceed 2.5mm, otherwise there will be shrinkage or wrinkage on the surface. However, if I have only this think shell, how do I fasten a motor firmly on that?


We did some research on the web and Joining Plastic said:


Mechanical fastening:

There are a number of fasteners designed for use with plastics. Threaded fasteners work best on thick sections. Thread-forming screws are preferred for softer materials, while thread-cutting screws work best on harder plastics. Push-on locknuts and clips may be better for thinner sections. If a fastener has to be removed a number of times, metal inserts are recommended. They may be molded in place, forced, glued or expanded into holes, or inserted ultrasonically.

Since ABS plastic is not something "softer", I guess thread-cutting type might be used; on the other hand, ApexFasteners also lists Thread Forming for Plastic. What is the difference between cutting and forming type?