Machining Guidelines - Compression Molded PPS


TECATRON PPS can be easily machined with conventional metal working tools. A high degree of precision can be obtained by using moderate cutting speeds and fast feed rates with carbide-tipped machine tools.

In general, the best surface speeds are 80 to 100 SFM (0.4 to 0.5 m/s) and the rate of travel should be relatively fast. A slow feed results in excess heat from friction and will tend to result in poor surface appearance. If a coolant is desired, ethylene glycol or anti-freeze works well.

Although fairly deep cuts of up to 1/8" can be made, finish cuts should be no more than .005 inches of material, and final cuts should be as little as .001 inches.

Unlike injection molded stock shapes, compression molded stock shapes tend to have more stock to remove to achieve the finished part. During the machining process, excess material removal may cause stress to build up within the material because of localized heating at the cutting point. Therfore, if a large amount of machining is to be done, a second annealing procedure may be required to prevent cracking. Typically, these types of problems can be elimated by "roughing out" the part (machining close to the finish size) and annealing before final machining.


Annealing should be done in a forced air oven capable of reaching temperatures of 450 degress Fahrenheit. Before annealing, parts must be dried 3 hours at 300°F. Allow parts to heat up at a rate of 20°F per hour to 450°F. Allow to soak at this temperature for a minimum of 2 hours or 6 hours per 1" cross section. Allow parts to cool at 20°F per hour to ambient temperature. Let parts stabilize in temperature 24 hours before finishing machining.