Abstract: A piston or plunger is made by passing an annular sealing member blank around a piston body and by moving it towards a central outer cylindrical surface part of the piston body defined between first and second circular edges. The sealing member blank is deformed into tight engagement with the central outer cylindrical surface part and into grooves or depressions formed therein. In this manner, a tubular sealing member, which extends axially along the central outer surface part, and which has opposite first and second ends extending beyond the first and second circular edges, respectively, is formed. Thereby both of these opposite end portions of the tubular sealing member may function as sealing lips.

Abstract: A piston or plunger and a method for making the same A piston or plunger comprises a piston body and a sealing member. The piston body is preferably made from metal by moulding, such as casting or pressure moulding and sintering. The sealing member is made from a thermoplast, such as polytetrafluoroethylene (PTFE). The piston body has an outer or an inner peripheral surface part in which axially extending depressions or grooves are formed during moulding of the piston body. The axially extending grooves may be open at one or at opposite ends. An annular sealing member blank is applied to the peripheral surface part and is deformed and forced into tight engagement with the peripheral surface part and into the grooves or depressions formed therein. The sealing member formed is also exposed to a heat treatment. The piston or plunger having the sealing member applied to an outer peripheral surface part may, for example, be used in shock absorbers.