Liquidity in the sheet forming machine

by:Mengxing     2020-03-27
Plastic under certain temperature and pressure filling mold ability is called liquidity. Too easy to cause the material overflow excessive liquidity, filling, imperfect, organization sulfur loose plastic, resin and filler separately accumulate, easy sticky mold and make the demoulding and difficult to clean up and defects such as premature hardening; Flow is too small, underfill, not easy molding, molding pressure. Sheet machine as a kind of plastic machinery, also the ability to use that. The main factors influencing the liquidity has: ( 1) Plastic varieties. General common thermoplastics liquidity can be divided into three categories: 1) Liquid are nylon, polyethylene, polystyrene, polypropylene, cellulose acetate. 2) Liquidity in general have ABS, organic glass, polyformaldehyde, polyvinyl chloride (ether. 3) Illiquid hard polyvinyl chloride, polycarbonate, polyphenyl ether, polysulfone, fluorine plastics. ( 2) The mould structure. The form of gating system, size, layout, Such as the cavity surface roughness, runner section thickness, cavity form and exhaust system) , the cooling system design, melting flow resistance factors are directly influence the flow of the molten material. And mold design is also an important key system cup machines. ( 3) Molding process. 1) The temperature. Material temperature is high, the liquidity. But different plastic vary. Polystyrene, polypropylene, polyamide and poly (methyl methacrylate, ABS, AS, polycarbonate, and cellulose acetate plastic influences of liquidity changes with the temperature; And polyethylene, polyformaldehyde liquidity is affected by temperature changes smaller. Now, lunch box machine basic use is the main material of polystyrene, polypropylene, polyamide. 2) Pressure. Injection pressure, the liquid by the shearing action, also increase the liquidity, especially PE, polyformaldehyde is more sensitive. That prompted lower melting temperature, the increased flow resistance factor ( Such as plastic pieces of wall thickness is too thin, the corner with sharp corners, etc. ) , liquidity will be lower.
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