Leaking, so as to prevent the mold surface from frost and moisture caused by overcooling. In the molten plastic, while checking whether the mold cooling channel is For the water vapor caused silver streaks, the mold venting holes shouldīe increased or vacuum vents should be adopted, to minimize the gas remaining Well as the cold slug well should be increased, so as to improve the venting conditions Third, in aspects of mold design and operation, to deal with degradationĬaused silver streaks, the sections of the gate, the sprue and the runner, as The screw speed should be reduced or venting screw applied. Streaks, the backpressure and screw compression ratio should be increased, while Prevent local overheating of the melt, and slow down the screw speed andįorward speed to shorten the pressurization time for the water vapor caused silver The barrel and the nozzle, reduce the residence time of the melt in the barrel, Second, when it comes to processing and operation, to deal withĭegradation caused silver streaks, it is necessary to lower the temperature of Material must be fully dried according to the requirements of the resin. Raw material, reduce the amount of recycled materials, and remove the residualįoreign materials in the barrel for water vapor caused silver streaks, the raw With a uniform pellet size as much as possible, screen out the powder in the To eliminate silver streaks, we should start from the following threeįirst of all, with regard to raw material selection and processing, toĭeal with degradation caused silver streaks, it is necessary to select resins Plastic cannot be completely vented, the water vapor caused silver streaks willīe produced on the surface of a plastic product. If the vapor generated by the volatilization of water in the molten To produce silver streaks, especially true for the super absorbent resins suchĪs PA and HIPS. Generated when the water volatilizes cause the surface of the plastic product Is that the water content in the raw material is too high, wherein the bubbles Another example is that the main cause of the water vapor related silver streaks In a “V” pattern, of which the tip faces away from the center of the The marks left by these small bubbles on plastic product surface are arranged Partial thermoplastic degrades and gas decomposes after being heated. For example, the degradation caused silver streaks are smallīubbles that are formed and distributed on the surface of plastic products when Silver-white stripes caused by elongated flat bubbles, of which the main types includeĭegradation caused silver streaks and water vapor caused silver streaks.Īll types of silver streaks are generated by the volatiles precipitatedįrom the melt front. The most commonly seen form of the silver streak is the needle-like Moreover, someĬracked or burnt plastics will also lead to silver streaks on product surface. Silver streaks will also be generated on product surface. Of air cannot be successfully vented during the plastic injection molding process, Material, a certain amount of air is often trapped in the melt. In addition, in the plasticizing stage of the raw plastic They are not fully dried before injection molding, the residual water will beĬonverted into water vapor during the plastic injection molding process, thus accordinglyĬausing splatter marks on product surface. Many plastic materials absorb a lot of moisture during storage. They radiate outward in a fan-shaped manner from the gate location. ![]() Material, or the decomposition and burning of mixed dissimilar plastics. Silver marks / silver streaks are splatter marks on product surface whichĪre caused by the volatilization of air and moisture contained in the plastic Silver streaks caused by insufficiently dried plastic material
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