We have one shot peening process in our facillity that wears out the Almen holder screws very quickly. This process is set for a nominal 17.8A intensity using AWS-62 per AMS 2431/4 media. My attitude towards this has always been to keep a box of spare (button head hex recess) screws for the operators to change as often as they desire. However, I am changing my opinion as we have done some time study work in that work area. Basically it slows down the operator greatly when he has to work to get the hex wrench into each screw recess. This particular process has a number of almen holders in various locations (lots of screws). The hex wrench actually no longer fits into the screw recess after a single intensity curve effort.
Recently I experimented by buying two batches of screws from vendors, we stripped them of black oxide in our plating department lab, then sent them to a vendor to carburized them to HRC57 at the surface (like J442 holder). Next we made a fixture from a perforated steel bar and installed a repeating pattern of Carburized A, Carburized B, stock, Carburized A, Carburized B, stock, etc. Next, begain exposing this to shot peening stream for increasing number of passes. We inspected and photographed the screws between each interval. I continued the test until the stock screw was completely unusable where both batches of carburized screws were still in excellent shape.
I have concluded that the carburized screws will save us valuable operator time and clearly make sense. Next we are either planning to A)start making our own hardened screws or B)find someone who is already selling these c) send my data to Jack Champaign and convince him that he should start offering bags of carburized screws for sale to anyone with the same need.
FEEDBACK PLEASE?? Realizing that others of you out there have everyday experience working with even higher intensities and unique situations, what are you doing? Has anyone ever hoped someone begins selling a hardened screw as a commodity? Anyone care to offer them for sale to me?
In case you are wondering, we also operate other processes at lower intensities and with smaller media sizes where the stock Almen screws last for weeks of use.
