Tube in PPS CMP 1000 mm beige

A tube in PPS CMP is a compression molded turning blank in polyphenylene sulfide, the material designers reach for when both the heat and the chemistry have outgrown the ordinary engineering plastics. The tube is supplied in the natural color beige and a length of 1000 mm, ready to be turned into rings, sleeves, seats and other rotationally symmetric parts for hot and chemically aggressive environments.

The numbers first. The continuous service temperature reaches 230 °C, the density is 1.36 g/cm³ and the flammability rating V0 per UL 94; the last without flame retardants, since the polymer itself is hard to ignite. Strength and stiffness are high and are kept far up the temperature range, and creep under load is low even when it is hot.

Chemical resistance is the grade's second strong suit. Below 200 °C PPS has in practice no solvent; acids, bases, fuels and hydraulic fluids do not get at the material either in normal concentrations. Add good resistance to radiation and the picture emerges of a plastic for environments where most other organic materials gave up long ago. That also makes the material choice easy to defend in a risk analysis.

The precision deserves a paragraph of its own. PPS takes up extremely little moisture and therefore does not move with the humidity, and the grade holds tight tolerances; parts that have to fit exactly at 200 °C are precisely the kind of job the material is made for. According to the manufacturer's documentation the grade also meets the semiconductor industry's Copy Exactly requirement for reproducibility between production batches.

The semiconductor industry in particular is one of the biggest users: fixtures, holders and components in wet bench processes where hot chemicals are part of daily life. Elsewhere in Swedish industry, PPS rings and sleeves turn up in pumps and valves for chemical process, in sealing and bearing parts close to hot media and in oven and drying equipment where POM and PET bowed out long before. The energy sector also picks PPS for parts close to hot oils and gases.

The tube format is chosen for economic reasons. Ring shaped parts are turned from tube with considerably less waste and shorter machine time than from solid rod, and compression molding, which is what CMP stands for, gives heavy cross sections with low internal stress. The stock stays put in the machine even when you take away a lot of material, which is worth its weight in gold in a material with this price tag.

Machining makes no strange demands: sharp carbide tools, moderate depths of cut and good chip evacuation give a fine surface and stable dimensions, and the chips are short and manageable. The material is stiff and somewhat brittle, so avoid sharp internal corners and give thread roots a small radius. Let the blank reach the workshop temperature before the final fit is measured in.

The dimension program is extensive, with dozens of combinations of outer and inner diameter; 180/125 mm and 180/130 mm are two examples from the list. Blanks cut to length we arrange with CTS, our cut to size service, and full mechanical, thermal and electrical data are in the manufacturer's TDS.

So where does PPS land among its neighbors? PVDF is plenty when the chemistry is the problem but the temperature stays around 140 °C, and PEEK handles more mechanical load at an even higher temperature but at a clearly higher cost. PPS is the step in between; nearly PEEK level on chemistry and heat, at a considerably milder price tag.

Not sure whether PPS is enough or whether the part calls for PEEK? Call us and we will sort it out.