Abstract: A novel method of leak proof attachment of the outer edge of a flange-type sheet metal element in the bore of a steel cup-shaped valve tappet acting as a hydraulic play-compensating element for a combustion engine comprising (a) reducing the diameter of the bore of the valve tappet in two steps from the open end, the axial spacing of the two steps being greater than the thickness of the sheet metal element, (b) placing the outer edge of the sheet metal element on the second step and (c) simultaneously axially applying pressure on the first step with a die and heating by electric resistance with leads connected to the die and the hold-down ram and apparatus for the process and the product produced thereby.