Rapid Plastic Injection Molds

Roseville, CA -- Extreme Machining reports that its proprietary process for manufacturing plastic injection molds can help speed the process of getting parts to market. The company reportedly goes from making prototypes to the injection molding stage within a span of two weeks. It can also save costs by using the injection-molded parts for life cycle testing and to check for fits of mating pieces.

To manufacture the molds, Extreme Machining makes a heat-resistant model that is mounted in a custom-made crucible. A custom mix of molten metal is then poured into the crucible and allowed to cool. The insert is prepared for mounting, followed by machining of ejectors and gates. The step that requires the most time is the making of the heat-resistant model, according to Extreme Machining President Robert Moore.

Extreme Machining recently used the process to make a mold for a 1/2-oz. ABS part. The part had two spherical ears, 1/2-inch high, with a counterbore and through hole on the ears. Mr. Moore said that the mold made some 10,000 parts without noticeable wear. A mold was also made for another small part, 1/2-inch in diameter and 1.75 inch long. It had two tapers, two flats with a cored hole, and cooling lines incorporated into the insert. This mold also made 10,000 pieces without noticeable flash or breakdown of defined edges.

A major benefit of the process, Mr. Moore said, is that overall costs are substantially less for production parts. Besides permitting early identification of flaws in molded parts, the process permits design changes to be made without needing to save an already existing hard-tooled mold. Surface textures can also be incorporated into the mold using currently available methods.