Sheet in PEKEKK 3000x300 mm black

PEKEKK is a high performance semi-crystalline plastic in the same family as PEEK, developed for components where operating temperature, stiffness and chemical resistance are all at the top at the same time. The sheet is used where a structural part has to keep its shape and load capacity at temperatures that ordinary engineering plastics gave up on long ago. It is a clear step up from PEEK when the margin against operating temperature has to increase or the service interval has to be extended.

Technically the material handles 260 degrees continuously and up to 300 degrees for short periods. The density is about 1.32 g per cubic centimeter. Tensile strength to ISO 527 is 134 MPa and ball indentation hardness is 275 N per square millimeter, which gives a hard and wear resistant surface even without surface treatment. Notched impact strength is low, around 4 kJ per square meter, which means the material has to be designed with rounded corners and without sharp notches to avoid crack initiation under load. Water absorption is extremely low, 0.03 percent, which contributes to good dimensional stability in a humid environment. The material is UL 94 V0 rated and gives off little smoke and toxic gas in a fire.

Chemically PEKEKK stands up to almost every common industrial chemical, acids, bases, oils and hot steam without swelling or weakening. The material also holds up to high pressure washing and repeated steam sterilization. At very high concentrations of strong acids or polar aromatics the grade should always be checked against the exact operating environment, but across the board the tolerance is unusually high. It is one of the few plastics that takes continuous contact with hot steam without losing shape over time.

The natural color is beige to brownish, and it is often supplied in black after carbon black pigment is added. The sheet has an even surface after pressing and takes face milling to very fine tolerances. The color is consistent through the whole thickness, which is an advantage when you have to mill deeper cavities without risking a color shift on the surface.

As a sheet, PEKEKK is used for load-bearing parts where PEEK does not give enough margin against operating temperature or stiffness, or where a higher long term temperature gives a longer service interval. Typical uses are components in oil and gas equipment, bearing and bushing material in process and pump applications, insulating parts in semiconductor and vacuum manufacturing, fixtures in soldering ovens for advanced electronics and wear strips close to hot processes. The material is also found in medical technology where high sterility, biocompatibility and dimensional stability are requirements, and in aerospace parts where fire requirements, weight and temperature have to be handled at the same time.

Machining follows the same method as for PEEK. Use sharp carbide tools, moderate cutting speeds and clear cooling to keep the working temperature in the material down. Semi-crystalline plastics are sensitive to heat build-up in the cutting zone, which can leave internal stresses in the finished parts. For critical tolerances or geometries with uneven wall thickness a gentle stress relief anneal before final machining is recommended. Drill larger holes in steps, and do not let chips collect in the cut. For threading, form taps or cutting taps with a polished chip chamber are recommended.

The sheet is supplied in fixed dimensions and thicknesses. Pick a thickness close to the finished size, the margin costs more in PEKEKK than in most other plastics because the raw material is more expensive. For larger runs it is worth calculating the cutting layout and material waste before ordering. For single parts it is easier to start from the next larger stocked thickness and accept the waste.

PEKEKK is not a first choice when PEEK is enough, but a clear step up when PEEK is on the limit for operating temperature, stiffness or chemical resistance. The difference in continuous service temperature, from about 250 degrees for PEEK to 260 degrees for PEKEKK, can be decisive when the part sits next to a hot process or in an autoclave with small margins.

In designs against metal, PEKEKK behaves predictably even through large temperature swings, which is why it often stays as the plastic part in environments where other plastics drop out. When press fitting insert bushings the material keeps its grip over a long time with no measurable creep. Screwed joints work well if the tightening torque is matched to the hardness of the material, since point load in a hard and relatively rigid plastic more easily gives local cracks if you pull too hard. Bonding works with high temperature epoxy after a light surface activation, and where needed plasma activation is recommended for the best adhesion.

The narrow 3000x300 mm format in black suits long strips and sealing blanks close to heat.

Want help deciding whether PEEK or PEKEKK is right for your part? Get in touch, we will go through temperature, load and chemical environment together.