Under what circumstances should a mold temperature mach […]
Under what circumstances should a mold temperature machine be used to heat the mold, and when should a chiller be used to cool the plastic mold. The following are some conditions for injection molding.
1. Closing mold pressure: In principle, it should be greater than the total pressure of plastic injection into the mold, based on no burrs.
2. The pressure and speed have partly the same relationship acting in the mold. The purpose is to make the raw materials enter the mold evenly, thoroughly, and fill the corners in an appropriate amount. Too low will cause short shots, shrinkage, too high to have hairs, over-saturation, sticky mold, burnt, easy to damage molds and high internal stress and other undesirable phenomena.
3. Speed: The speed of the speed determines the condition of the raw materials in the mold runner and the finished product. There will be burrs, oversaturation, scorching, short shots, shrinkage, poor bonding and easy breaks when they are slow.
4. Temperature: different raw materials, different temperatures, too low solution glue color uneven, the internal stress of the finished product will increase. Because the temperature is too low and the pressure is too high, it may cause the screw to break, too high, the product has burrs, and the temperature difference occurs due to cooling, which causes shrinkage. The raw material will decompose, turn yellow, change color, and break easily. The cooling time becomes longer and the gas is not easy. Exhaust, there will be gas.
5. Back pressure: The resistance of the screw when the screw is rotating and feeding is called back pressure. Its function makes the raw material more compact in the transportation and compression. It can make the air and water of the raw material be discharged from the back of the screw. So that the sol does not contain gas components that affect the surface of the finished product. There will be bubbles and silver streaks on the surface. The high will overheat, agglomerate, overflow the glue, the cycle is long, and the screw will not retreat. At the same time, the application of loosening is very important: when the back pressure is low, some raw materials should be loosened, and some do not. When the back pressure is high, be sure to use the loose retreat and pay attention to the distance or not to interfere with the air and not to overflow the glue as the criterion.
6. The mold temperature and the length of the cooling time will affect the sticking of the finished product, shrinkage, dimensional tolerance, surface brightness, cycle, etc., and should be adjusted in time according to the actual situation. In addition, acrylic, PC, such as the thickness of the finished product, must have The mold temperature will not produce bubbles and stress.