A method for injection molding at least one first housing part and for joining at least two housing parts of a drug injection device comprising the steps of: providing a first housing part by injecting a first molding material into a first injection mold to shape the first housing part whereby the first molding material is a plastic material having non-adhesive properties, providing a second molding material having adhesive properties upon activation, injecting the second molding material into the first injection mold containing the first housing part or into a second injection mold after the first housing part has been transferred from the first mold to the second mold, wherein the second molding material is injected onto or around the first housing part at a location which is intended for adhesive connection between the first housing part and a second housing part, whereby the location is in the overlap area between the first part housing and the second housing part once the first housing part and second housing part have been joined together, providing the second housing part, wherein the inner dimensions of the second housing part are larger than the outer dimensions of the first housing part, aligning the first and second housing parts (1,2) along a common central axis, assembling the first housing part and the second housing part by axially moving the second housing part over the housing first part thereby covering the location intended for adhesive connection, activation of the second molding material having the adhesive properties to join the first housing part and the second housing part, whereby the activation of the second molding material comprises heating, and whereby the second housing part is made from a metal, preferably aluminum and whereby the heat is conductively transferred from the outside of the second housing part through the metal to the location intended for adhesive connection or whereby the second housing part is heated by inductive heating. providing a first housing part by injecting a first molding material into a first injection mold to shape the first housing part whereby the first molding material is a plastic material having non-adhesive properties, providing a second molding material having adhesive properties upon activation, injecting the second molding material into the first injection mold containing the first housing part or into a second injection mold after the first housing part has been transferred from the first mold to the second mold, wherein the second molding material is injected onto or around the first housing part at a location which is intended for adhesive connection between the first housing part and a second housing part, whereby the location is in the overlap area between the first part housing and the second housing part once the first housing part and second housing part have been joined together, providing the second housing part, wherein the inner dimensions of the second housing part are larger than the outer dimensions of the first housing part, aligning the first and second housing parts (1,2) along a common central axis, assembling the first housing part and the second housing part by axially moving the second housing part over the housing first part thereby covering the location intended for adhesive connection, activation of the second molding material having the adhesive properties to join the first housing part and the second housing part, whereby the activation of the second molding material comprises heating, and whereby the second housing part is made from a metal, preferably aluminum and whereby the heat is conductively transferred from the outside of the second housing part through the metal to the location intended for adhesive connection or whereby the second housing part is heated by inductive heating.