What is Hot Plate Welding?

The process of hot plate welding uses a heated platen to melt the joining surfaces of the two halves of a thermoplastic part. The part halves are brought into contact with a precisely heated platen for a predetermined period. After the plastic interfaces have melted, the parts are brought together to form a molecular, permanent, and often hermetic bond. A properly designed joint welded under precise process control often equals or exceeds the strength of any other part area.

Advantages of hot plate welding include precise control of the melt temperature, excellent weld strength, ability to weld large, complex parts, and ease of attaining hermetic seals.

The simplified diagram below shows the stages in the hot plate welding process:

hot plate welding joining thermoplastic parts

  1. Parts are loaded in their nests.
  2. The heated platen moves forward between the parts.
  3. The parts contact the heated platen. The plastic begins to melt.
  4. After the parts' joint interfaces are plasticized, the nests move back allowing the heated platen to retract.
  5. The parts are pressed together so that a molecular bond forms.
  6. The nests move apart and the finished assembly is unloaded.

Typical applications include automobile lighting, batteries, fuel tanks, and washer bottles.

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