Black Spot Color Change Possibility Factors Of Injection Mold

- Mar 27, 2018-

          Injection molds are also one of the common types of molds. During the manufacturing process, we often find black spots or cause discoloration and coking during injection molding. This is a common problem in injection mold manufacturing. The main cause of this problem is plastic or The barrels of added ultraviolet absorbers, antistatic agents, etc. are overheated and decomposed, or the time spent in the barrel is too long, and they are decomposed and coked, and are formed along with the melt injection cavity. In order to avoid these problems, we can analyze the following four aspects:1, machine side:(1) As the heating control system is out of control, the cartridge is overheated and disintegrated. (2) Defects due to prolonged fixed heating due to defects in the screw or barrel causing the melt to stick in and accumulate. Check if the rubber head cover is worn or if there are metal foreign objects inside. (3) Some plastics, such as ABS, are exposed to high heat and cross-linked coke in the barrel. It is difficult to melt under conditions where almost the original shape of the particles is maintained, and is broken into pieces by screw pressure.

2, mold:(1) mold exhaust is not smooth, easy to scorch, or the size of the gating system is too small, resulting in excessive shear caused by coking. (2) Inappropriate oil lubricants and mold release agents in the mold.3. Plastics:Excessive plastic volatiles, excessive humidity, excessive impurities, too much recycled material, and contamination.4, processing:(1) The pressure is too high, the speed is too high, the back pressure is too large, and the speed is too fast to decompose the material temperature. (2) The barrel should be cleaned regularly to remove additives that are inferior to plastics.