Custom Carbon Steel Grip Plug For Aerospace Application

This featured grip plug is a critical aerospace part and is composed of 4140 stainless steel that was heat treated to 32-38 HRC. To manufacture the insert, a variety of CNC Swiss Turning processes were applied. Using a SR-32J Star Swiss type lathe with live tooling, we turned each side and turned the start of the lead thread to a chamfer of .06 x .45 degree with the M14 x 2.0 for the major diameter and pitch diameter, and with a thread relief having 2 radii of .060″. Next, using the machine’s y-axis capability with live tooling, we milled two .670″ wrench flats into the stem. Throughout the machining process we maintained tight tolerances of +.001″-.005″, with features on a common axis to be GD&T run-out of .010″ max. To conduct inspection we relied on an OGP touch probe and a vision system CMM, as well as micrometers, a custom thread gage, a drop gage, and a digital optical comparator.
The final Grip Plug featured .875″ round bar stock, with a .786″ outside diameter and a thread relief diameter of .450″. We then labeled each carton with part and lot numbers, as well as the quantity. Packaging was limited to 50 parts per box, in accordance with aerospace bag and tag requirements. Included in each order was a raw material certification, complete with chemical and mechanical properties, and quality control verification. The project took 4 to 6 weeks to complete, and was then shipped to our PMA client for use in the aerospace industry.