Method and apparatus for injection molding

A method and apparatus for producing an injection moulded plastics article comprises introducing a supply of plastics material ( 20 ) into a mould space ( 13 ), supplying a first stream of pressurised fluid into the molten plastics material to form a fluid containing cavity ( 25 ) therein, maintaining fluid pressure in the cavity until the plastics material can sustain the form dictated by the mould surface. During the step of maintaining fluid pressure in the cavity, at least a portion of the first stream of pressurised fluid is vented or allowed to vent from the cavity, and simultaneously a second stream of pressurised fluid from a second source ( 26; 40; 41 ) is supplied to the cavity, which second stream replaces that portion of the first stream which has vented from the cavity.