Plastic molding processing of plastics materials hot - performance Union star packaging machinery

Should be considered in the process of hot forming of plastic material thermal performance is more, including materials, heat distortion temperature, softening temperature range, thermal state mechanical strength, heat capacity, thermal conductivity, thermal expansion coefficient, melting heat, thermal diffusion coefficient and thermal stability, etc. Thermal deformation temperature is one of the important of thermal processing should be considered in temperature conditions, the internal temperature of the material in the process of forming limit in theory cannot be higher than the no-load thermal deformation temperature of the material itself, or in the process of forming its own gravity parts will be damaged parts. One commonly used for large parts. 82 mpa under thermal deformation temperature of the material as the processing temperature, while for small parts press 0. 46 mpa under the load of material's thermal deformation temperature for hot forming limit temperatures. Due to the surface of the plastic sheet in practical forming temperature higher than the internal temperature, so the process control temperature often much higher than the thermal deformation temperature of the material. Materials in the process of hot forming temperature drops quickly, need material in a wider temperature range can keep appropriate flexibility, plasticity and elasticity, to ensure the integrity of their final products edge part. Materials also need to have a high thermal state mechanical strength, thickness of or under thermal state once the draft will be an imbalance, this request is used to heat molding thermoplastics shoulds not be too low molecular weight. In addition, through introduction of strong polar group in molecular chain or crosslinking structure limit molecular chain of slip each other, improve the material thermal processing performance. The heat capacity of the materials needed to reflect unit quality material rising temperature heat, according to the size of specific heat and density of sheet forming can be calculated when the heater needs to provide an effective heat. Plastic thermal conductivity is low, thick wall products hot forming process of preheating stage may appear on the surface has been melt, blister or decomposition, and the internal hasn't been softening phenomenon, therefore should be considered on select material with high thermal conductivity of plastic varieties, craft also should consider to use double side heating or far infrared heating heating mode. In practical production, the heating stage plastic thermal expansion can not be considered, but the size of the cooling phase contraction can't be ignored. In products containing metal insert or need to embed the plastic metal containers, should be in consideration of plastic shrinkage rate is greater than the metal. Using male mold molding, plastic due to shrinkage in the mold surface and male mold are difficult to pull out, thermal expansion coefficient is larger in molding materials such as polyolefin and polyvinyl chloride ( pvc) Pay particular attention to this point in a etc.