Method for treating a plastic part (1), which comprises a surface, comprising the steps: A) irradiating at least a part of the surface with a treatment radiation (10) to obtain a modified surface area (4), the modified surface area being capable of absorbing a heating radiation (20) to an extent greater than the unmodified surface area (5), and B) irradiating the modified surface area (4) with the heating radiation (20) at least in a section so that the plastic part (1) is heated and softened in a region defined by the irradiated section of the modified surface area (4).
