Machining PVDF

PVDF belongs to the group of fluoropolymers – polymers whose carbon chain is partly occupied by fluorine atoms. These carbon-fluorine bonds are extremely stable and give PVDF its high chemical and thermal resistance. Unlike PTFE, which is even more resistant but cannot be machined or welded conventionally, PVDF machines, welds and thermoforms excellently. It is stiff, strong, dimensionally stable and absorbs virtually no moisture.

PVDF machines very well – turning, milling, drilling and sawing produce clean, dimensionally accurate results. As PVDF absorbs virtually no moisture, the components are dimensionally stable; we ensure sufficient cooling and adapted cutting parameters to avoid heat build-up. This is how we reliably produce precision parts for chemical, semiconductor and cleanroom applications – from single pieces to series production.

PVDF is worthwhile whenever chemical resistance and purity must be combined with good machinability – for example:

• Components for chemical plant engineering (pumps, valves, fittings, pipes)
• Components for the semiconductor industry and cleanroom technology (wet bench, front-end)
• Parts in contact with aggressive media and ultrapure liquids
• Applications requiring weathering and UV resistance outdoors
• Components that must be flame-retardant without flame-retardant additives

PVDF is a high-performance plastic and is priced considerably above standard engineering plastics such as POM or PA, but below PTFE and PEEK. As a rough guide, semi-finished stock prices are in the range of about 20–45 €/kg. The component price is determined mainly by the semi-finished shape and dimension, material utilisation (offcut), machining effort and lot size. We are happy to quote binding prices on request based on your drawing.

Equally important are the limits of the material:

• Contact with strong bases (alkalis) and amines – PVDF is attacked here
• Continuous service above about 140 °C – then PTFE or PEEK are options
• Applications with a very tight budget – standard plastics such as POM or PA are considerably cheaper
• When only the very highest chemical resistance is required without machining/welding – then PTFE

An honest assessment – and how the disadvantages can be mitigated in practice: Advantages:

Disadvantages:

Practical tip: PVDF plays to its strengths wherever aggressive media and purity meet – for example in semiconductor manufacturing or chemical plant engineering. If even higher chemical or temperature resistance is required, we recommend PTFE or PEEK; for simple engineering parts without media attack, POM or PA are more economical.

• Outstanding chemical resistance (the best after PTFE)
• High purity – ideal for semiconductor and cleanroom
• Inherently flame-retardant (UL 94 V-0), without additives
• Machines, welds and thermoforms well
• Weathering- and UV-resistant, high continuous service temperature
• Not resistant to strong bases (alkalis) and amines
• Higher price than standard engineering plastics
• Continuous service limited to about 140 °C
• Combustion products contain hydrogen fluoride – observe fire safety