① The gas undergoes a large compression to produce back pressure, and this back pressure increases the resistance of the molten material to the mold filling flow, preventing the molten plastic from filling the mold quickly, making the mold cavity unable to fill, and causing the plastic edge to be unclear.
② There are obvious visible flow marks and fusion seams on the product, and the mechanical properties of the product are reduced.
③ After the gas is compressed, it will penetrate into the inner layer of the plastic, causing the plastic to produce surface quality defects such as silver streaks, pores, loose tissue, and delamination.
④ After the gas in the cavity is compressed, heat is generated, which causes the temperature of the plastic to rise locally, and the plastic melt decomposes and changes color, and even burns and carbonizes.
⑤ Poor exhaust reduces the filling speed, increases the cycle of the part forming (especially high-speed injection), and seriously affects productivity.
Tags: mold exhaust