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Plastic Forming Techniques - Coggle Diagram
Plastic Forming Techniques
Pultrusion
Pultrusion is a method that used to manufacture components with continuous lengths and constants cross-sectional shape.It is a continuous process, easily automated dan can form many type of shape.
General process of pultrusion is continuous rovings of the reinforcement are impregnated with the resins then pulled through the heated die. In this step, Curing takes place in the heated die and oven. A puller is used to pull the whole system with certain speed.
Filament winding
Filament winding is a process to produce a hollow cylinder shape.
The general process of filament winding is as follow. First, the fibers are passed through the resin bath follow by continously wound onto the mandrel.After number of layers, curing is carried out in an oven or room temperature.Once the resin has cured, the mandrel is removed or extracted, leaving the hollow final product.
Thermoforming
Thermoforming is a process of reshaping of plastics under the influence of heat and pressure or vacuum. This method is used to produced utililize thermoplastic sheet or film and big parts such as swimming pool or motor vehicle parts.
The general process is the thermoplastic sheet is heated until it softens. Then, the hot and pliable material is forced against the contours of a mold by using either mechanical, air or vacuum pressure. The mold is held ang wait it cool, and plastics retains its shape.
Rotational molding
Rotational molding is a method that uses gravity inside a rotating mold to achieve a hollow form.It is an alternative to blow molding for making large, hollow shapes.
A predetermined amount of polymer powder is loaded into a cavity of the split mold that is heated and rotated simultaneously so that the powder impinges on all internal surface of the mold gradually forming a fused layer of uniform thickness. While still rotating, the mold is cooled so that the plastic skin solidifies.
Compression Molding
The mold is held between the heated platens of the hydraulic press. The molding compound is placed in it. Then, the platen closes with sufficient pressure to minimize flash. The compounds soften and flow to shape, and then chemical cure occurs due to high temperature. Finally, the press is opened and the molding is removed.
Blow molding
（3 type of blow molding)
Extrusion blow molding
Injection blow molding
Stretch blow molding
Blow molding is a process that utilize air to shape softened polymer tubes.
General process of this method is melting the resin-done in extruder to therefore form molten resin into the parison. The parison is placed inside a mold and inflated so that the plastic is pushed outwards against the cavity wall. The part is then cooled and ejected. Finally, the part is trimmed
Extrusion
Extrusion is the continuous semi-finished product with uniform cross section. This method can produced tubes, sheers and film to complicated profile.
This process comprises the forcing of molten material through a shaped die by means of pressure.
Screws are used to progress the polymer in molten or rubbery state along the barrel.
Calendering
Calendering is a method that used calender which is a machine that equipped with two, three or more heavy internally heated or cooled roolers that rotate in opposite directions at even or uneven speeds. to produce rubber sheets of various lengths and thickness and also widely used for skin coatinf of fabrics including shower curtains, tablecloths and laminating film.
Transfer molding
Transfer molding is development of compression molding in which reservoir of the molding compound is located in the mold and upon closure is transferred via runner to the cavities. It is used to produce small parts
Injection molding
The basic principle of injection molding is to inject molten polymer into a closed mold where it is solidifies to give the product.
Blown Film Extrusion
Blow Film Extrusion is a process that produced relatively thin film and bag.
A continuous tube is extruded clamped between rollers at one end and blown with compressed air to form large hollow tube having a very thin wall. The tube continuously flattened and placed on a roll for bag production or it can split opened and used for film. No mold is required for the process.
