Radiation crosslinking of polyamide 66 with electron beams alters the material characteristics. This leads to a varied relationship between the process, the structure, and properties for vibration welding crosslinked polyamide 66. A three-dimensional network of covalent bonds in the amorphous areas results in an impeded melt flow and altered welding characteristics. A possible way to influence this three-dimensional network is to change the mold temperature during the injection molding process. At higher mold temperatures, the degree of crystallinity increases and leads to a decrease in the resulting covalent bonds in the amorphous area. The altered degree of covalent bonds influences the vibration welding process. Higher temperatures during the process can be achieved. The scope of this article is to show how the mold temperature influences the material characteristics and, by extension, the resulting processing and welding characteristics of radiation crosslinked polyamide 66. Optical, thermal, mechanical and chemical investigations serve to highlight the influence of the mold temperature on the material and the welding process of radiation crosslinked polyamide 66. POLYM. ENG. SCI., 58:E207-E214, 2018. (c) 2017 Society of Plastics Engineers