Positioning device and positioning assembly for holding a flat flexible part, and sheet material processing machine

A positioning device for holding a flat flexible part, especially a sheet, on a positioning surface, the positioning device comprising:

• a body having a suction opening for aspiring the flat flexible part, wherein the suction opening is arranged within the positioning surface being an outer surface of the body, and a fluid port being in fluid communication with the suction opening, wherein the fluid port is arranged within a connection surface being an outer surface of the body, and
• an abutment protrusion being arranged on the connection surface for abutting the positioning device against a base part to which the positioning device may be mounted and a sealing protrusion being arranged on the connection surface for compressing a gasket being interposed between the positioning device and the base part,
• wherein a height of the abutment protrusion by which the abutment protrusion protrudes from the connection surface is bigger than a height of the sealing protrusion by which the sealing protrusion protrudes from the connection surface.