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Author: MULAN –Plastic Molding Manufacturer
The previous article introduced the principle of nitrogen hollow injection molding and the benefits of using nitrogen hollow injection molding. Then we will analyze the main points of nitrogen hollow injection molding process. 1) The injection point of the gas is generally about 90% of the filling cavity of the injection molding machine. The filling state must be matched with the injection action of nitrogen, and the boosting effect of the gas should be considered at the same time. 2) After the gas is injected, it is necessary to prevent the leakage of the gas nozzle at the injection point and the leakage of the product tail.
3) After the gas enters the colloid, it will delay the direction of least resistance. Such as thicker sections in plastic parts. 4) The tail pressure of the gas holding pressure should be discharged at low pressure.
5) When the plastic is cooled and formed, its pressure is controlled by the gas, not by the injection molding machine. 6) When the gas is not smoothly blown into the middle of the product, the plastic parts will be blown. 7) The gas in the plastic must be discharged into the atmosphere or recycled for use before the mold is opened.
8) When the plastic is cooled, the plastic product will shrink, which will be compensated by the pressure of the gas. 9) To prevent gas leakage in the barrel of the injection molding machine, it should be properly added between the low pressure holding time and the melt delay time, which is about 60% of the working cycle of the injection molding machine. 10) The purity of nitrogen must be greater than 99.99%. 11) Nitrogen is delivered to the mold through a booster, and delivered through a dedicated 400bar high-pressure pipeline.