Stabilized core injection molding of plastic

A method of cyclic injection molding of hollow plastic products, utilizing a mold chilling cavity with a core, in which the dimensions of the plastic products are controlled by stabilizing the core, wherein each production cycle comprises the steps of:

• (a) injecting a hot molten first plastic at a first temperature and a first pressure from at least a first runner through a first gate into the chilling cavity so that the cavity is not filled and so that the injected plastic does not obstruct injection from a second gate;
• (b) cooling the injected first plastic in the chilling cavity to thereby cool and at least partly solidify the first plastic;
• (c) injecting, subsequent to injecting the first plastic, a hot molten second plastic at a second temperature and a second pressure from a second runner through the second gate into the chilling cavity whereby the cooled injected first plastic is sufficiently cooled and at least partly solidified to stabilize the core by impeding any movement of the core caused by injecting the second plastic and whereby the injected second plastic fills the cavity and fuses with the previously injected plastic;
• (d) cooling the injected second plastic in the chilling cavity to thereby solidify the fused unit;
• and
• (e) ejecting the solidified molded unit of the hollow plastic product.