Sheet in PPSU 2000x620 mm black

Sheet in PPSU is a semi-finished product in a high performance sulfone plastic, made for designs that have to handle hot water, steam and autoclave cycles without losing strength or dimensional stability. The material is amorphous, has a yellowish translucence in its basic tone and combines high temperature resistance with toughness down in sub-zero temperatures. The sheet is used for fixtures in medical technology sterile rooms, holders for washer disinfectors, insulators and parts in electrical cabinets exposed to steam, as well as structural parts in aircraft, vehicles and process industry where fire and smoke properties are regulated.

The technical core of PPSU is the hydrolysis resistance. The material is not broken down by repeated steam the way many other engineering plastics are. The density is about 1.29 g/cm³, the design temperature is roughly 180 °C continuously and the material handles short peaks considerably higher. In the cold PPSU keeps its impact resistance down toward about -50 °C, which means the same part handles both an autoclave and cold storage without cracking or letting go of its shape. The fire class is V0 according to UL94, and the smoke given off in a fire is low; that opens up use in cabin and passenger spaces where a smoke class has to be documented. Water absorption at equilibrium is around 0.6 percent, which is low enough not to affect the measurements of the parts in operation, but enough to require drying before hot forming.

PPSU is machined on ordinary workshop machines. Use sharp carbide tools, a lower feed than for POM and PA, and make sure the cooling is sufficient, since the material is heat sensitive in the small cutting gap. The sheet can be cut in a band saw, milled, drilled, tapped and polished. It takes color in CNC milling without melting if the feed is kept within reasonable limits and chip evacuation is good. Gluing works well with epoxy and cyanoacrylate after degreasing, and the sheet can be ultrasonically welded. Heat bending is possible at around 200 °C but requires dry material; dry at 120 °C for at least four hours before forming, otherwise the surface goes cloudy and the bend can crack in the radius. Stress relieving in an oven before heavy machining pays off on thick sheets.

Typical uses are sterilization trays and locking parts in washer disinfectors, fluid blocks flushed with hot water, insulators in electrical cabinets where steam or condensation occurs, cabin and interior parts in aircraft and vehicles where a fire and smoke class is a requirement, as well as structures in clean rooms where the material can be cleaned with steam or strong alkaline agents without aging. Thin sheets are also used as transparent inspection windows where PC is not enough thermally. In medical technology PPSU is particularly well established since it handles both validated autoclave programs and the aggressive enzymatic cleaning agents used in washer disinfectors between surgical procedures.

When choosing between PPSU and neighboring materials: PEI is somewhat stiffer and cheaper but yellows more in an autoclave and is broken down by more aggressive alkaline cleaning. PSU is cheaper but loses impact resistance faster. PEEK is better at really high temperatures and chemical loads, but costs considerably more and is not transparent. PPSU is therefore a good choice when you need the combination of toughness, steam resistance and fire class in the same part without going all the way up into the PEEK segment. Against PC, PPSU simply lasts much longer under thermal and chemical loads without cracking.

The sheets are stocked in thicknesses and formats that cover both small fixture parts and larger machine parts. When machining thick blocks it is worth leaving a couple of millimeters of extra stock for final polishing, since amorphous materials that cool slowly can move minimally during the first hours after the last milling pass. On small parts it is rarely noticeable, but on precision fixtures it can be the difference between a limit gauge fitting or not.

Do you need help choosing a thickness, or would you like advice on machining parameters for a specific part? Get in touch, we take the drawing through the workshop and come back with a proposal for material and cutting data. We can also help combine sheets with round rod or hollow bar in the same quality if your design contains both flat and cylindrical parts.

Black sheet at 2000 x 620 mm. The longer board gives material for several trays or larger covers for equipment that is steamed in an autoclave time after time.