Injection moulding method

A method of injection moulding an article, the method comprising the steps of:

• (a) providing an injection mould comprising a plurality of movable mould parts and at least one stationary mould part defining a mould cavity of the injection mould, the injection mould further comprising an injection inlet for injecting molten thermoplastic resin material into the mould cavity;
• (b) disposing the mould parts in a first configuration so as to define a first intermediate moulding cavity;
• (c) injecting molten thermoplastic resin material into the first intermediate moulding cavity through the injection inlet to fill the first intermediate moulding cavity with the molten material to form a first intermediate article comprising molten material;
• (d) closing the injection inlet;
• (e) after the closing step, moving at least one of the movable mould parts to dispose the mould parts in a second configuration so as to define a second intermediate moulding cavity at least partly filled with the molten material to form a second intermediate article comprising molten material;
• and
• (f) moving the at least one of the movable mould parts to dispose the mould parts in a third configuration so as to define a final moulding cavity of the injection mould filled with the molten material, the final moulding cavity defining a cavity outer surface which defines the outer shape of the final article to be moulded, and wherein the first intermediate moulding cavity has the same volume as the final moulding cavity;
• wherein the first intermediate article has a first length to thickness L/T ratio, the second intermediate article has a second L/T ratio and the final article has a third L/T ratio, wherein each L/T ratio is a ratio, averaged along a maximum length of the respective article, of the maximum length of the article and a thickness of the article along that maximum length, and wherein the first L/T ratio is lower than the second L/T ratio and the second L/T ratio is lower than the third L/T ratio.

A method of injection moulding an article, the method comprising the steps of:

• (a) providing an injection mould comprising a plurality of mould parts defining a mould cavity of the injection mould, the plurality of mould parts including first and second movable mould parts, and the plurality of mould parts further includes a further mould part which is on an opposite side of the injection mould from the first and second movable mould parts, the injection mould further comprising an injection inlet for injecting molten thermoplastic resin material into the mould cavity, wherein the injection inlet is located in the vicinity of the first movable mould part and the second movable mould part is remote from the injection inlet;
• (b) disposing the first and second movable mould parts in a first configuration so as to define a first intermediate moulding cavity, in which first configuration the first movable mould part is in a first rearward position and the second movable mould part is in a first forward position, wherein the first intermediate moulding cavity is defined substantially between the first movable mould part and the further mould part opposite thereto, a peripheral edge of the first intermediate moulding cavity is defined by a side surface, which is a non-moulding surface, of the second movable mould part, a moulding surface of the first movable mould part is located spaced from an opposite moulding surface of the first further mould part, and a moulding surface of the second movable mould part is located adjacent to an opposite moulding surface of the further mould part, and no portion of the first intermediate moulding cavity is defined between the second movable mould part and the further mould part;
• (c) injecting a volume of molten thermoplastic resin material into the first intermediate moulding cavity through the injection inlet to fill the first intermediate moulding cavity with the molten material;
• (d) closing the injection inlet;
• (e) after the closing step, moving the first and second movable mould parts thereby to dispose the first and second movable mould parts in a final configuration so as to define a final moulding cavity of the injection mould filled with the molten material, the final moulding cavity defining a cavity outer surface which defines the outer shape of the article to be moulded and the final moulding cavity have the same volume as the first intermediate moulding cavity;
• and wherein the steps of disposing and moving the first and second movable mould parts to the respective forward and rearward positions with respect to the opposite moulding surface define a width of the first intermediate moulding cavity and the final moulding cavity and a corresponding wall thickness of the moulded article.