PRC Plast (Thailand) Co., Ltd realizes the importance of product and service quality. Therefore, we improve the efficiency of our production technology by applying the advanced manufacturing system to the production of plastic sheets and packaging products to meet the highest level of customer satisfaction.
     
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Plastic sheet extrusion process

    Plastic sheet extrusion process means melting and pressing plastic to form a continuous sheet; then, rolling it up for storage or cutting it into specific sheet size by thermal extrusion. The principle of plastic sheet extrusion is that plastic resins are fed into the sheet extrusion machine; then, they will be melted, pressed, and mixed in the chamber between screw and barrel of the extrusion machine by means of the screw rotation at high speed causing the friction between screw and barrel. This mechanism generates the energy from shear force aiding in homogeneous melting and mixing. Then, the melted resin is pressed through the screen to filter out any contaminant and incompletely melted resin and to generate sufficient pressure for extruding melted polymer through the T-die by using rollers to control the sheet size as required. The chiller has a function to control the temperature of the roller and to transfer such temperature to the plastic sheet through the roller in order to allow the plastic sheet to set. Then, the edge of plastic sheet may be trimmed by using the winder that is appropriate for the required roll size.

     
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Plastic forming process

Plastic forming typs :

  • Cold Bending
  • Heat Bending
  • Thermoforming
  • Vacuum Forming
  • Pressure Forming
     
  • Cold Bending
    The cold bending can be used for general bending. The plastic can be bent into curved or even circular shape based on the condition that the radius of a circle must be at least 100 times of its thickness; for instance, the plastic thickness is 2 millimeters so, the bending radius must be at least 200 millimeters or the circle diameter equals 400 millimeters.

  • Heat Bending
    Heat bending is the process that uses heat for bending plastic. Mainly, the material used for this process is acrylic and is often used to make a point-of-purchase display.

  • Thermoforming
    Thermoforming means forming plastic by using air pressure or mechanical pull force to stretch the plastic while it is softened by heat in order to make work-pieces that have the same shape as molds. Therefore, the thermoforming process requires air pressure, vacuum pressure, and mechanical pull force or the combination of these three forces to form the plastic into shape as molds. Raw materials mainly used for this process are plastic sheet and plastic film. Two methods mainly used for plastic forming, which can stretch plastic sheet to a determined size, are as follows:

  • Vacuum Forming
    Raw materials are fed into the vacuum forming machine at the temperature ranging from 200 to 400 degrees (depending on plastic type and thickness). When the plastic sheet is fed into each frame of the machine, it will be heated up to a level suitable for forming. Then, the machine applies the vacuum to suck the plastic sheet down firmly against the mold to form a required shape and waits until the plastic cools down by using the cooling system inside the mold to allow the plastic to set before removing it from the mold and taking it out of the machine.

  • Pressure Forming
  • Pressure forming: Pressure forming is the process that heats up the plastic sheet in the same manner as the vacuum forming. However, there is a difference in the forming method by applying the air pressure to the heated plastic sheet so that it is forced firmly against the mold to form a required shape and using the cooling system inside the mold to cool down the plastic before removing it from the mold and taking it out of the machine. The pressure forming has a higher production rate, which results in the lower cost of production process. It is mainly used for a large quantity of plastic packaging production in various industries such as food, snack, drink, and electronic industries.