factors of discoloration of black spots on injection molded parts
factors of discoloration of black spots on injection molded parts
1. Machine
As the heating control system is out of control, the barrel is overheated and decomposed into blackDue to the defects of screw or barrel, the molten materials are stuck in and accumulated, and the decomposition is caused by long-time fixed heating. Check whether the rubber head kit is worn or whether there are metal foreign matters in it
Some plastics, such as ABS, are cross-linked and coked by high heat in the barrel. They are difficult to melt under the condition of almost maintaining the original particle shape, and are crushed by screw and then entrained into the parts
2. Mould
Mold exhaust is not smooth, easy to scorch, or the size of the gating system is too small, shear too much, resulting in coking
There are improper oil lubricants and release agents in the mold
3. Plastics
Too much volatile matter, too much humidity, too much impurity, too much recycled material, and polluted
4. Processing
If the pressure is too high, the speed is too high, the back pressure is too high and the speed is too fast, the material temperature will decompose.
The barrel should be cleaned regularly to remove additives that are less resistant than the plastic
