What are the primary conclusions of IFIs research report (IFI RR-2) to determine if pitch diameter size has influence on fastener performance?
Study conclusions were as follows; 1.System 21 thread gaging demonstrated the detection of out-of-tolerance pitch diameters in all test lots as well as System 22 gaging. 2.For aerospace nuts, pitch diameter size had no bearing on the fastener’s tensile strength performance. It was clear that when the minor diameter was oversized beyond limit requirements, tensile strength was adversely affected. 3.The aerospace nut’s pitch diameter size had no measurable effect on joint performance as related to vibration, torque-tension, or fatigue. 4.The pitch diameter size of commercial bolts correlated to tensile strength in that smaller pitch diameters yielded lower strength, but in all cases, bolts exceeded minimum strength requirements. 5.Even the poorest fit commercial bolt and nut combination (bolt undersized by 0.006″ and nut oversized by 0.034″) passed all tensile and proof load strength requirements. 6.All commercial bolt and nut combinations exceeded minimum torque-tension performance requ
