Injection mould

An injection mould for manufacturing disc-shaped plastic objects, which mould comprises:

• a first mould part and a second mould part, with the mould parts mutually movable between a closed position and an open position of the injection mould, and with the mould parts defining in the closed position of the injection mould a mould cavity into which in the closed position of the injection mould heated plasticized plastic is injectable by supply means,
• wherein the mould parts each include a mirror block with a flat mirror surface, with the mirror block of the first mould part having a mechanical pattern on the flat mirror surface thereof, which pattern corresponds with information for imparting onto the objects to be manufactured,
• wherein the second mould part includes a venting ring having a cylindrical inner surface partly bounding the mould cavity,
• wherein the mirror block of the second mould part has a cylindrical outer surface,
• wherein the venting ring and the mirror block of the second mould part are positioned such that the cylindrical inner surface of the venting ring and the cylindrical outer surface of the mirror block of the second mould part are slideable over each other,
• wherein the venting ring, the flat mirror surfaces and the mirror blocks are made of steel,
• wherein at least one of the cylindrical inner surface of the venting ring and the cylindrical outer surface of the mirror block of the second mould part is provided with a coating which does not include TiN and which reduces a coefficient of friction between the cylindrical inner surface of the venting ring and the cylindrical outer surface of the mirror block of the second mould part to a value of about 60% of the value obtainable with a TiN coating.