[en] The manufacturing methods of cross-linked polyethylene foams are classified into two categories based on the type of cross-linking. One is chemical cross-linking using peroxide as a cross-linking agent. The other method is cross-linking by irradiation. Chemical cross-linking produces a fairly thick foam sheet with a comparatively high degree of cross-linking. Chemical cross-linking excels in thermo-forming but, due to a rough surface, the product is lacking in adhesive property and printability. We attempted to improve the surface condition of foam sheet without damaging the features proceeding from chemical cross-linking. At the pre-stage of foaming, and by irradiating the surface at low voltage, the resultant foamed sheet with smooth surfaces and excelling in mechanical properties can be produced. (author)