Mold Best Assurance Company Limited
With injection Molding, granular plastic is fed by gravity from a hopper into a heated barrel. As the granules are slowly moved forward by a screw-type plunger, the plastic is forced into a heated chamber called the barrel, where it is melted.
The sequence of events during the injection molding of a plastic part is called the injection molding cycle. The cycle begins when the mold closes, followed by the injection of the polymer into the mold cavity. Once the cavity is filled, a holding pressure is maintained to compensate for material shrinkage.
The time it takes to make a product using injection molding can be calculated: Total time = 2M + T + C + E
Although most injection molding processes are covered by the conventional process description above, there are several important molding variations including:
Optimal process settings are critical to influencing the cost, quality, and productivity of plastic injection molds. Process optimization is done using the following methods.
When filling new or unfamiliar injection molds for the first time, where shot size for that mold is unknown, an injection molding company technician/tool setter usually starts with a small shot weight and fills gradually until the mold is 95 to 99% full.
Not only injection mold temperature determines melt temperature as it moves quickly through the mold. The melt temperature itself as it starts its journey through the injection mold (self-evidently) is the reference point. Speed of injection, particularly in thin sections, is of huge influence, as it will determine the degree of shear heating.
Many engineering materials like PBT (Polybutylene terephthalate) have a tendency of out-gassing. The best practices that I have to date are: Add 10mm wide vents spaced 30mm from each other all the way around parting line. Always follow the recommendations of the material company for vent depth.
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