Method for welding a connection between a first joining surface of a first molded part and a second joining surface of a second molded part

A method for welding a connection between a first joining surface of a first molded part and a second joining surface of a second molded part disposed under the first molded part, comprising:

• preparing the first molded part to be at least partially transparent for a primary beam of a first radiation source and at least partially absorbent for a secondary beam of a second radiation source, and the second molded part to be at least partially absorbent for the primary beam;
• moving and bracing the first molded part and the second molded part by a clamping device with the first and second joining surfaces in contact with one another;
• and
• sequentially and chronologically irradiating a region that includes a first focus of the primary beam on the second joining surface and a second focus of the secondary beam within a volume of the first molded part, so that when the primary beam is on, the secondary beam is off, and visa-verse such that the region receives radiation in a manner wherein radiation is either being emitted by the primary beam or the secondary beam.