Statistical Process Control is the process control used for machining & finishing to define the level of surface roughness of the product, using the international standard ANSI/ASTM B46.1 to intermediate and give clear specification of surface finish of the fittings. Statistical Process Control, means continuous monitoring of the process in order to prevent beforehand defective parts from being processed. Control limits assures that processes are adjusted to center of curves. SPC transforms quality control from inspection to prevention. It assures more consistent product performance and more reliable deliveries. Every batch of fittings is statistically controlled during machining to assure excellent surface finish, per HAM - LET Surface Roughness Test Procedure. Testing verifies conformance to: micro inch / (micro meter).Per our specifications The following plot shows the avarage & maximum valves of the Ra. max as they are monitored by S.P.C.

The following page is showing the real measurment taken and controlled by S.P.C. and the capability and stability of the process.

The following plot shows the average & maximum values of the Ra. max., for “LET-LOK Cones” level, as they are monitored by SPC.

S.P.C. at Ham-Let is used as an control aid through many machining and finising processes, specially on surface roughness of the U.H.P. HTC components & Let-Lok Fittings.