Standard tapped holes have a surface finish of approximately 63 RMS. Friction loss is excessive and as a result consistent clamping load at any given wrench torque cannot be provided.

8-15 RMS. This superior surface finish holds friction loss to a minimum when the screw is installed into a FASTMAN Insert thus providing maximum clamping load at any given wrench torque. This assures reliability of the assembly.

Photoelastic study of tapped hole & bolt assembly shows disproportionate load (as high as 40% of total) being carried by the first one or two threads. Note the concentration of stress lines appearing predominantly near the beginning and diminishing towards the end.

The photoelastic study of an assembly with FASTMAN Insert proves that the load is evenly distributed along the entire length of the bolt. Note the dark stress lines distributed over all threads. Possibility of a fracture in the part or failure of the bolt, due to dangerous stress concentrations on the first few threads, is thus eliminated.

Lead and angle errors between members in a standard tapped hole is always possible, due to inaccuracies in the tapped hole and in the cut or rolled thread screw. The members being rigid, they cannot compensate for lead and angle errors resulting in a disproportionate load on the first few threads.

FASTMAN Inserts being made of precision-formed wire, are elastic and self adjusting. They compensate for any lead errors between the mating threads and also angle errors in the threads, thus assuring that all threads are engaged and that stress concentration is eliminated.

Corrosion in a standard threaded assembly often results in seizure of the screw in the tapped hole. Efforts to dislodge the screw sometimes snaps the screw itself or the threads are stripped.

FASTMAN Screw Thread Inserts being made of 18-8 stainless steel offers zero risk from corrosion and seizure. Threaded assemblies with FASTMAN Inserts can be disassembled even after prolonged exposure to corrosive atmosphere. FASTMAN Inserts retain their strength and anti-corrosive property even at elevated temperatures up to approximately 370?C.