Method for manufacturing a composite work piece for a drug delivery device, comprising the steps: Providing a first work piece part 1 and a second work piece part 2, arranging both work piece parts 1, 2 with respect to each other in such a way that both work piece parts 1, 2 are in mechanical contact with one another in a contact area 3, irradiating a surface of the first work piece part 1 with electromagnetic radiation, thereby softening the first work piece part 1 and/or the second work piece part 2 in a region adjacent to the contact area 3, and joining the first work piece part 1 to the second work piece part 2 in the contact area 3 for the composite work piece. Furthermore, a composite work piece for a drug delivery device is provided.