Injection Molding is very good way to produce a lot types of plastic products, especially in Automotive industry. However, not perfect as everything in the world, there are some problems when we use this technology in manufacturing. The below are some common problems with Injection molding and their causes and resolutions.
The first problem that we will talk about is “Black specks spots or streaks”. The reason for this problem is that during the injection process, plastic is hot and it will burn onto the walls of cylinder and then flake off into the melt. Or, we also can thank about that air is trapped inside mold and then causes the burning. Another one is that parts of granules burn against the wall.
So how to solve this problem? At first, we can have mold vent properly or remove any trapped air by purge heating. Besides, in some cases, we need use a lubricated plastic.
The next problem that might happen is that there are bubbles inside the finished part. This will happen when the plastic granule still has moisture. In order to avoid this, we should get the material dried before using.
Flashing is also one of common problems of injection molding. If we let material get too hot, it will happen. Another reason is the pressure of injection is too high, or the pressure of clamping is too low. The way to solve this problem is to reduce the temperature of material, or lower the injection pressure. We also can reface the parting line, or increase the pressure to clamp.
If the mold is too cold or injection pressure is too low, we will see a problem called “Pore Finish”. This also occur when there is water on the surface of mold or excessive mole lubricant. To solve this, we can base on the cause of the problem to handle. If it is because of mold temperature, we should increase it at a moderate level. Or just increase the injection pressure when it is too low.l Besides, we always have to ensure that the mold is clean and no cooling leak. Also, we can repaint or polish the mold.
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