TWI Frequently asked questions
by Felicity Chipperfield
The surface of the heater plate is usually coated with PTFE to prevent molten material from sticking to it. For flat plates, PTFE-coated glass fibre fabric is usually used. Complex heater plate surfaces tend to be spray coated with a uniform layer of PTFE, typically 50µm thick. However, PTFE cannot be used at temperatures greater than about 270°C. For higher temperature welding operations, uncoated aluminium-bronze plates are used to minimise adhesion of the molten polymer.
With or without a coated plate, it is important to ensure that no molten polymer adheres to the plate, since this will cause contamination in subsequent welds. If this is a problem, the plates should be cleaned between each weld.
Also see FAQ: How should I clean heater plates for welding PE (polyethylene) pipes?
