A Comprehensive Guide to Plastic Molding Techniques

Plastic molding is a manufacturing process in which liquid plastic is shaped using a mold to create a finished plastic product. The process involves a liquid polymer such as polyethylene or polypropylene to be placed into a rigid frame or mold, so the polymer can take its shape. Various ranges of heat and pressure are applied to create a plastic product of the desired shape.

Types of Plastic Molding

Listed below are the six popular plastic molding techniques that are used to create various plastic products. Depending on the budget, expertise, and resources, one can choose a plastic molding process that best suits their business.

1) Rotational Molding

In rotational molding, large hollow parts of plastic products are produced by placing the liquid resin into a metal mold. This metal mold is rotated in an oven until the resin coats the inside of the mold. Once the mold is cooled the plastic gets hardened and is removed from the mold forming an even-walled plastic product. It is commonly used in the manufacturing of plastic bulk containers, storage tanks, car parts, storage bins, and marine kayaks.

 2) Injection Molding

Injection molding is used to produce customized plastic parts in high volumes. The procedure involves injecting molten plastic at very high pressure into a metal mold. Once the mold cools it is opened to form a solid plastic part. The injection molds are generally made of steel or aluminum and can produce very precise plastic parts. Injection Molding is used to create automobile dashboards, bumpers, electrical switches, medical devices, and plastic bottle caps.

3) Blow Molding

Blow molding is a method used to make hollow, thin-walled, custom plastic parts. The process is similar to glass blowing. Blow molding produces plastic products with uniform wall thickness. The process involves heating the plastic and injecting air in it. The hot plastic is blown like a balloon and is pressed against the walls of the mold to form the desired shape. Once the mold is cooled and hardened the plastic part is ejected. Blow molding is commonly used in producing fuel tanks, bottles, and drums.

4) Compression Molding

Compression molding involves placing heated plastic into the hot mold and then pressing into a required shape. Compression molding ensures that the plastic comes in sheets and retains its maximum strength. Lastly, the compressed plastic is cooled, trimmed and removed from the mold. The procedure is heavily used in producing automotive parts as it requires parts that are strong and durable.

5) Extrusion Molding

Extrusion molding extrudes the melted plastic material directly into the die, making the process different from other molding processes. This process is unique because the final plastic product takes the shape of the die, and not the mold. Extrusion molding is very useful in manufacturing plastic parts that require continuous length and uniform cross-sections. It finds its application in the manufacturing of PVC piping, straws, plastic decking, hoses, and straws.

6) Thermoforming

Thermoforming involves a plastic sheet called thermoplastic to be heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a final product. The process involves the usage of several types of molds and processes to produce inexpensive plastic materials. Thermoforming is used to create plastic products such as fridge liners, lids, clamshells, and disposable cups.

Selecting the right plastic molding process for a particular application can aid the goal for higher productivity and better yields. If you are in the plastic molding business, then Plastivision is a great platform for you to showcase your product range and network with industry professionals. Book your booth today!

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