Hot plate welders are used to fuse two thermoplastic components together. This is achieved by melting a sacrificial interface between the components using profiled hot plates, then pressing the two components together until the melt interface solidifies.

Common products welded using this process are plastic injection moulded or blow-moulded parts.

Granroth produces hot plate welding machines of various sizes with interchangeable tooling, allowing multiple part assemblies to be welded using one machine.