The main reason for the black spots in the discoloration coking of injection molded products is that the plastic or added ultraviolet absorbers, antistatic agents, etc. are decomposed in the cylinder by overheating, or the residence time in the cylinder is too long to be decomposed and coked, and then injected along with the melt. The cavity is formed. Analysis of the cause of black spots in the color change coking of injection molded products The main reason for the black spots of the color change coking of injection molded products is that the plastic or added ultraviolet absorbers, antistatic agents, etc. are overheated in the barrel, or the residence time in the barrel is too long. Decomposition, coking, and then into the cavity with the melt injection. analyse as below: Brass Y Strainer Valves,Brass Y Valve,Brass Y Shut Off Valve,Brass Y Strainer Valve AS-SUR INDUSTRIAL VALVE CO., LTD. , https://www.assur-valve.com
[1. Machine side]:
(1) Due to the loss of control of the heating control system, the barrel is overheated and the decomposition is blackened.
(2) Due to the defects of the screw or the barrel, the melt is caught and accumulated, and it is subjected to long-time fixed heating to cause decomposition. You should check if the rubber head kit is worn or if there is any metal foreign matter inside.
(3) Some plastics, such as ABS, are subjected to high heat in the cylinder and cross-linked and coked. In the case of almost maintaining the original particle shape, it is difficult to melt, and is crushed by the screw to be entrained into the workpiece.
ã€2. Mold aspect]:
(1) The mold is not vented, easy to burn, or the size of the pouring system is too small, and the shearing is too much to cause coking.
(2) There are improper oil lubricants and mold release agents in the mold.
[3. Plastics]:
The plastic has too much volatile matter, too much humidity, too much impurities, too much recycled material, and is contaminated.
[4. Processing aspect]:
(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.
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