Abstract: Provided is a method of making a multi-property polyurethane part by RIM having a surface layer and an interior layer. The surface layer and the interior layer have different properties. The pressure in the cavity of the mold is reduced and a surface forming RIM polyurethane material is injected into the evacuated cavity, whereby the surface layer of the molded part is formed by RIM. An interior forming RIM polyurethane material is injected into the evacuated cavity, whereby the interior of the molded part is also formed by RIM.

Abstract: An apparatus having a vacuum chamber or chamber, wherein the changing manner of the mold can be improved, the sealing structure of the vacuum chamber or an injection nozzle is simple, and the cost of the apparatus is reduced and preservation of the apparatus is improved. The apparatus has a vacuum chamber for surrounding a mold into an airtight situation. The vacuum chamber includes an upper casing and a lower casing, and they are being divided by a parting line defined by mating peripheral edge surfaces which incline upwardly from an operator-side to an opposite-side. An O-ring as a sealing member of the vacuum chamber is positioned between the peripheral edge surfaces.

Abstract: It is object of the present invention to provide a method by which a variable property component, such as two-color parts, having the interior covered with a thin film of the surface area is molded from polyurethanes by RIM, eliminating the need for separately applying a mold release agent or colorants to the cavity surface. Greater latitude in design due to varying physical characteristics is provided.

Abstract: A mixing head of an injection molding machine has an injection plunger for opening and closing a plurality of orifices and a spool plunger for opening and closing a plurality of circular passageways. The plunger and the spool are disposed parallel to each other.