Sheet in PSU 3000x300 mm amber

PSU is a polysulfone sheet that lands between the engineering and the high performance thermoplastics. It keeps its mechanical properties up to 160 degrees continuously and takes short excursions higher than that. That makes the material welcome for components that have to be steam dried, autoclaved or run through washing in alkaline lye without going brittle or cloudy.

The sheet is light transparent with a faint yellow tone in the basic version, often described as honey colored. The optics are enough for inspection windows, guards over lit instruments and sight glasses where a slightly warm tone is acceptable. Water absorption is about 0.2 percent, which is low for an amorphous material and contributes to good dimensional stability in a damp environment. The density is 1.24, the fire rating HB according to UL 94.

Mechanically PSU is stiff and impact resistant at the same time, a combination that is otherwise unusual in clear plastics. That means a face milled part can be pressure tested without shattering or deforming permanently. The tendency to stress cracking is limited against water based cleaning agents and alcohol in ordinary concentrations. Against strong chlorinated solvents, ketones and aromatic substances the material is sensitive, though, and it is worth checking against the actual process liquid before choosing.

The applications are often in medical technology, laboratory equipment and food processing. Filter housings, liquid reservoirs, sterile storage vessels, inspection plates in steam filled autoclaves, and windows in equipment where PC goes brittle after repeated heat cycles. PSU keeps its transparency and mechanics through several thousand autoclave runs, which makes the investment defensible despite a higher material price compared with PC.

In machining, the sheet mills, turns and drills cleanly. Tools have to be sharp and the feed adjusted so that the heat is led away with coolant or compressed air, since the material is heat sensitive during machining even though the end application is hot. Gluing is done with solvent based techniques or methylene chloride if a transparent joint is required; for mechanical joints threads and screws work if the hole is drilled with little preload. Annealing after machining is recommended for components that are to work close to the upper temperature limit, since it reduces internal stresses and the risk of cracking later.

Amber colored transparent sheet, 3000 x 300 mm. The transparency makes it useful for sight glasses and insulating parts.

The sheet is supplied in standard dimensions with a protective film on both sides. The protective film stays on through the whole machining stage and is pulled off only at installation, which protects the optical surface from scratches. Do you need help deciding whether PSU or PEI suits your temperature and chemical profile best? Get in touch with the temperature, the chemicals and the contact cycle, and we take it from there.