Plastic injection molding process involves the application of plastic, or polymer. The granular polymer is fed right into a heated barrel. Also, it is further melted and mixed inside the barrel with the rotation process of a screw type plunger, as heat is generated by the friction between polymer granules if the screw is rotating.
The double injection plastic mold is going to be forced into a mold cavity using the required final shape using a nozzle from the screw rotation action. The mold is relatively cold which can have cooling channels run through it. This leads to the molten polymer solidifies almost once the mold cavity is filled. The solidified part using the final required shape will then be ejected out when the mold open again. It will likely be further cooled off through the ambient air.
Plastic injection machine can be used to keep the mold set up as well as to melt the plastic and inject it in to the mold cavity.
Injection machine is classified by it tonnage. Tonnage is the clamping force how the machine use to clamp the mold during injection molding process. It may be ranged from less than 10ton to 5000 tons, rely on part size and materials used.
Another selection of injection machine is whether it is single injection machine or double injection machine. For double injection machine, it is going to have 2 list of screw plunger, hoppers and nozzles.
In Electronic plastic mold, there injetion many common defect as a result of process constraint and material properties.
Sink mark, short mold, wrap, silver streak, flow mark, flashes, weld line etc..
With better injection machine, material, skill and much better parts design, such defect might be overcome quite easily nowadays.