Abstract: A filter for absorbing electromagnetic radiation which is used in heating a welding zone wherein a first part is joined to a second part. The filter includes a filter housing which contains a chamber within which a fluid is placed. The fluid absorbs undesired wavelengths of radiation from a heating source before the radiation reaches the welding zone. A heat exchanger may be connected to the filter in order to cool the fluid during the filtering process.

Abstract: Method and apparatus for heat-welding two members by applying radiation, such as infra-red radiation, through one of the members to enter layer(s) interposed between the two members. Method relies on inclusions through thickness of the layer(s) to be responsive to said radiation to raise temperature through thickness and promote bonds at inter-faces with surfaces of said members. The bonds are assessed using thermal imaging camera detecting a near visible radiation arising from the layer(s), which radiation is different from infra-red used for heating.

Abstract: The invention relates to a welding head for heated tool welding, particularly of thermoplastic materials.