Assembly Considerations

The hot plate welding process uses an electrically heated metal plate to soften the surfaces of thermoplastic components to be joined. The heating elements are usually coated with PTFE or covered with PTFE film to avoid sticking. After the surfaces being welded are sufficiently softened, the heated platen is quickly removed and the components are held under light pressure until the bond is set. Hot plate welding is generally used for making butt welds. Figure shows a schematic representation of the process.

Some of the positive attributes of hot plate welding include the following:

Can be easily used for semi-crystalline materials that are difficult to weld with other methods such as ultrasonic welding
Suitable for welding dissimilar thermoplastic materials as each surface of the hot plate can be heated to a different temperature
Can be used to weld complex surfaces that can not be subjected to lateral motions involved in vibration welding
High joint strength can be achieved with the correct processing conditions
Components with walls as thin as 0.062 inch can be welded
If located properly, additional parts can be captured between the components being welded
Can create excellent fluid-tight seals

And the negatives of hot plate welding include the following:

It is associated with longer cycle times than other processes such as ultrasonic welding, etc. Typical cycle times may range from 15 seconds to several minutes depending on the part size
Can leave beads of material on the sides of the welded joints. This excess material is trimmed in a secondary operation if required for aesthetics
Parts made of hygroscopic materials may have to be dried before welding
Higher equipment, fixture, maintenance, and energy costs than other techniques such as vibration welding

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