Plastic injection molding process involves the use of plastic, or polymer. The granular polymer is fed right into a heated barrel. It is also further melted and mixed in the barrel by the rotation process of a screw type plunger, as heat is generated through the friction between polymer granules if the screw is rotating.
The double injection plastic mold is going to be forced into a mold cavity together with the required final shape through a nozzle with the screw rotation action. The mold is relatively cold which might have cooling channels run through it. This will cause the molten polymer solidifies almost as soon as the mold cavity is filled. The solidified part with the final required shape is going to be ejected out as soon as the mold open again. It will likely be further cooled down with the ambient air.
Plastic injection machine can be used to keep the mold in place and also to melt the plastic and inject it in the mold cavity.
Injection machine is classified by it tonnage. Tonnage may be the clamping force how the machine use to clamp the mold during injection molding process. It might be ranged from less than 10ton to 5000 tons, depend on part size and material used.
Another variety of injection machine is whether it is single injection machine or double injection machine. For double injection machine, it will have 2 pair of screw plunger, hoppers and nozzles.
In Home appliances plastic mold-A TOP MOLD, there injetion many common defect due to 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 better parts design, such defect can be overcome without difficulty nowadays.