Machining PK natural

PK natural is an aliphatic polyketone – a semi-crystalline engineering thermoplastic that closes the gap between polyamide and POM. It combines exceptionally high toughness, retained even at low temperatures, with very good wear, chemical and hydrolysis resistance at low moisture absorption. PK natural shows an elongation at break of more than 70 % and a notched impact strength of 12 kJ/m² – considerably tougher than POM – at a yield stress of 70 MPa and a continuous service temperature of 100 °C. In sliding contact, wear is lower than with POM and PA; moisture absorption of 0.4 % is far below that of polyamide, so dimensions and strength remain stable even in humid environments. The material is resistant to fuels, oils, solvents and many chemicals, and hydrolysis resistant against hot water. With 1,700 MPa, the tensile modulus is lower than that of POM or PA 66, and the heat deflection temperature (HDT 83 °C) limits applications under high load at elevated temperature. Thermal expansion is comparatively high, and PK – like POM – is not resistant to strong acids and oxidising agents.

PK natural is one of the easiest engineering plastics to machine: sawing, turning, milling, drilling and thread cutting are straightforward with standard HSS or carbide tools, chips break short and surfaces come out clean. Good cooling via chip removal avoids heat build-up. For tight tolerances and thick-walled parts, we recommend intermediate annealing to relieve machining stresses; the low moisture absorption makes conditioning unnecessary. Because of the high toughness, chips tend to flow; sharp tools with a large rake angle and good chip removal ensure clean surfaces.

PK natural is used wherever components are exposed to high impact loads, wear and aggressive media – for example in the oil and gas industry, in mechanical engineering and in the automotive industry.

• Gears, sliding and guide elements under high impact load
• Components in contact with fuels, oils and chemicals
• Wear parts in conveyor and packaging systems

PK natural is calculated individually based on drawing or sample. The part price is determined mainly by the semi-finished form and dimensions, material utilisation and offcuts, machining effort and batch size. We are happy to provide binding prices on request.

The limits of the material are equally important:

• Lower stiffness than POM and PA 66
• Limited heat deflection temperature (HDT 83 °C)
• High thermal expansion, not resistant to strong acids

An honest assessment:

• Advantage: Very high toughness, even at low temperatures
• Advantage: Very good wear resistance and sliding properties
• Advantage: High chemical, fuel and hydrolysis resistance
• Advantage: Low moisture absorption (0.4 %)
• Disadvantage: Lower stiffness than POM and PA 66
• Disadvantage: Limited heat deflection temperature (HDT 83 °C)
• Disadvantage: High thermal expansion, not resistant to strong acids