Powder metering apparatus and powder metering method

A powder metering apparatus, comprising a peripheral wall defining in part a metering chamber (2) having a powder metering volume (3) and an outlet opening (11), a powder supply line (10), a diaphragm (5) reciprocally movable in the metering chamber relative to the peripheral wall between a first position for applying a negative pressure (8) to the metering chamber (2) and a second position to empty the metering chamber, wherein the diaphragm (5) bounds the metering chamber (2) and the diaphragm (5), together with a diaphragm holder (6) on which the diaphragm (5) is fixed, is adapted to be adjusted relative to the outlet opening (11) in order to set the powder metering volume (3), the peripheral wall (4) of the metering chamber (2) is constructed from a material which is more elastic than the diaphragm holder (6) material, so that the diaphragm holder (6) is sealed on the peripheral wall (4) of the metering chamber (2) as the diaphragm holder is moved along the peripheral wall, thereby eliminating any separate elastomer seals for sealing the diaphragm holder (6) with respect to the peripheral wall (4).