Patented metal/plastic self-clinching panel fasteners from Penn Engineering & Manufacturing, Danboro, Pa., install permanently in metal sheets as thin as 0.036 in.

PEM Type PFP assemblies are made up of a steel retainer and screw and a large ABS plastic cap. Because color coding is becoming more and more important, especially in electronics applications, the caps are available in various colors including red, yellow, green, orange, blue, violet, and standard black.

The spring action of the cap's plastic "fingers" lets the knob be held in a retracted position. PFP fasteners aren't spring loaded, but the cap acts as a spring-loaded panel fastener in keeping the screw retracted and out of the way when not engaged. The retracted screw won't damage, mar, or interfere with a mating panel as it is slid into place.

When tightened, the caps completely cover the retainer. By design, the bottom of the metal retainer lets the cap and screw float by 0.015 to 0.020 in., in case panels are misaligned. Though the panel fasteners can be hand operated, a metal universal slot Phillips drive is built into the screw and is standard.

Two screw lengths are available for unified or metric thread sizes ranging from #4-40 through #8-32 and M3 through M4.