Plastics Processing Techniques

There are many methods used to convert plastics materials into formed shapes and parts such as pellets and granules. The company is mainly engaged in Plastic Granulator, plastic extruders, Plastic Machinery Customization, Pelletizing Production Line, Recycled Plastic Resin Equipment and its products cover multiple fields.

Injection molding is the process of heating and homogenisation plastic granules in a cylinder until they are fluid enough to allow for pressure injection into a mold. In the mold the material will take the shape of the mold cavity. The benefits of this technique are the speed of production and the minimal requirements for the postmolding operations. This process is very effective for high-speed molding of such materials such as nylons, polyesters and polyurethanes.

Rotational molding is where finely ground powders are heated in a rotating mold until they reach melting point or fusion happens. The melted or fused material coats the inner surface of the mold. When cooled, a hollow finished shape can be removed.

Blow molding is the process of forming hollow plastic tubes. The process begins with melting down the plastic and forming it into a parison. A parison is a tube like piece of plastic with a hole in one end so that compressed air can pass through. The air pressure then pushes the plastic out to match the pattern of the mold. Once the plastic has cooled and is hard enough, the mold can be opened and the part taken out.

Thermoforming is where plastic sheets are formed into part through heat and pressure. Plastic sheets are heated in a large oven to the correct temperature that they can stretched into or onto a mold and cooled to the finished shape. This method is quite cost effective and is often used for sample and prototype parts.

Extrusion is used to make products such as tubing, pipes, sheets and wire. Other commonly extruded materials include ceramics, concrete, metals and foodstuffs. In this process plastic pellers or granules are turned to fluid, homogenised, and continuously formed.

Compression molding consists of molding preheated material into an open heated mold cavity. Pressure is then applied to compress, heat and turn the plastic into the form of the cavity shape. This process and transfer molding is primarily used for thermosets. A thermoset is polymer material that irreversibly hardens.

Transfer molding is similar to compression molding because the plastic is cured into a infusible state with heat and pressure. The difference to compression molding is that transfer molding involves heating the plastic to a point of plasticity before it gets placed into the mold. The mold then get forced closed with a hydraulically operated plunger.

Above are the main processed used in the plastics industries today but other processes which I haven't talked about are foam processes, calendering, casting and encapsulation.