In the manufacturing process of general Plastic Injection Mould, we often encounter some common problems, such as black spots often found, or discoloration coking during injection molding, but the main reason for these problems is that the injection molding products stay in the barrel. The time is too long, resulting in decomposition and coking of the injection molded product, which is formed in the cavity along with the molten material. What are the possible factors for the black dot color change in the injection molding machine? Below, China Servo Plastic Machinery Factory will share with you!
1. Machine side:
(1) Because the operation of the heating control system on the machine fails, the inside of the barrel is overheated to cause decomposition and blackening.
(2) Because the defects of the screw and the barrel cause the melt to get stuck and accumulate, the plastic is decomposed by the fixing and heating of the machine for a long time. At this time, the staff needs to check whether the rubber head kit is worn and whether there is metal foreign matter inside.
2, the mold side:
(1) Generally, if the mold on the mold is not ventilated, it is easy to burn, and the size of the casting system of the mold is too small, or the coking caused by excessive shearing.
(2) Black spots may also occur when improperly used oil lubricants, mold release agents, etc. are used in the mold.
The plastic has too much volatile matter, too much humidity, too much impurities, too much recycled material, and is contaminated.
(1) The pressure is too high, the speed is too high, the back pressure is too large, and the speed is too fast, the material temperature is decomposed.
(2) The barrel should be cleaned regularly to remove additives that are less resistant than plastic.