In 2012 the United States Council for Automotive Research (USCAR) performed extensive testing of thread-forming fasteners driven into light alloy castings with pre-cored holes. The purpose of the test, as made public in a subsequent report*, was to determine whether cost-savings could be achieved as had been done for many years with thread-forming fasteners being driven into unthreaded steel nut members. The report concluded that this recommended thread-forming fastener application would generate significant cost-savings for automotive manufacturers.
In the USCAR test, thread-forming screws and bolts were driven into light-alloy castings which had unthreaded pre-cored holes. The tests confirmed that drilling, reaming, tapping, gaging, cooling and cleaning operations could be eliminated. In addition, their respective capital-intensive machining and gaging equipment stations on the assembly line would no longer be necessary. In these tests the assembled joints in light-alloy material had clamp load values consistent with industry expectations for steel nuts and bolts. Several other positive results of driving thread-forming fasteners into pre-cored net shape holes were determined to be: (1) $.07-$.09 cost savings per fastener driven, (2) a “green” benefit-a significant reduction in electrical energy required to power unnecessary machines, (3) a shorter length assembly line footprint and (4) less capital investment in plant and equipment. USCAR concluded that if this application were universally adopted in North America, and with an estimated car build of 16 million vehicles, 500 fasteners per vehicle, and a savings of $.08 average per fastener, the total net cost-savings would total $640 million per year for automotive manufacturers.
The report herein referenced - USCAR FAS 1005: Machining Elimination through Application of Thread Forming Fasteners in Net-Shaped Holes was Copyrighted by USCAR in March, 2012.