From everyday objects to high-tech gadgets, plastic is a great material that can be easily shaped to produce almost any product. It’s so widely used, humans barely even notice just how prevalent it is in the world today.
But not all plastic goods can be produced by simply using the same methods. It would be absurd to think that medical prosthetics that are used to replace human body parts can be made using the same process as when simply making a plastic bottle. Plastic injection molding is really somewhat of an art, and requires manufacturers of plastic goods to know the ins and outs of producing high-quality goods that will serve their purpose adequately. In order to make different types of goods, manufacturers must know the different types of plastic molding and what how to apply each one.
Plastic injection molding is a very versatile way of producing plastic goods. The process involves injecting the plastic into a to a mold that’s shaped to produce a part that will have the desired form once it’s ready to be retrieved from the mold.
Reaction Injection Molding
This process is commonly used in the production of items such as air spoilers, auto-motive bumpers and fenders.
The process for reaction injection molding involves the use of thermosetting polymers that are first mixed together and then injected into a mold under high pressure by making use of an impinging mixer. The plastic mixture is left in the mold so that it can cure. Polyurethane is used most often for this type of injection molding.
Liquid Injection Molding
Liquid injection molding is done by injecting the mixtures into a mold using a variety of plungers containing the different parts of the final mixture. Usually there’s a mold containing the base forming plastic and another contain a mixture that serves as a catalyst, meant for activating the base forming plastic. After the mixture has hardened it can be released for the mold and the process is repeated.
Liquid injection molding is usually done using material such as silicones and acrylics.
Gas Assist Injection Molding
This low-pressure method of plastic injection molding is done by blowing nitrogen gas through the molded part in order to form it. The resulting part is often one with thick wall and channels through it. Items that can be made using gas assist injection molding include auto-motive headlight mounting modules and thick handles that are hollowed using this process.
Co-injection molding uses two materials, usually a cheaper material and a more expensive one. During the process, two polymers are injected into the same mold. Usually this method is utilized to cut down of production costs. By coating a cheaper polymer with a more pricey one, manufacturers are often able to produce an item at a lower cost without effecting its efficacy.
Fusable Core Injection Molding
Is a process that uses a core made of an alloy such as tin-bismuth that melts at a low temperature. This core is then placed in a plastic mold after which a it’s coated with a material such as nylon. After the plastic in the mold as been allowed to set, it’s taken to a core melting machine where the core is removed either by melting it or by dissolving it in a substance. For dissolving the core, a polymer such as soluble acrylate is used instead of tin-bismuth.
Rapid Injection Molding
The goal of rapid injection molding is to produce high volumes of good within the shortest possible amount of time. The process is done using a rubber plaster molding process, but is used for creating plastic goods very often. Instead, this type of molding is used to produce part from aluminium and zinc and the resulting parts often aren’t used for mass-production of goods.
Other Methods Of Molding Plastic
Apart from injection molding, there are also other methods to mold plastic. Here are a few of the alternative ways in which plastic can be molded.
Compression molding is done, as the name would suggest, by compressing plastic components in to the desired shape. This is done by heating both the plastic and the compression mold, after this the heated plastic is places in the mold and then shaped by applying large amount of pressure.
Compression molding is often used in the auto-motive industry, maily because the resulting components are very durable and plastics that are optimal to use in this process tend to make a good fit for the requirements that the components will have to live up to.
Blow Molding is the most economically practical way of producing large quantities of objects such as drinking bottles. It’s the ideal way of making hollow objects that don’t have various components. The process is similar to glass blowing, but is specially designed for manufacturing plastic goods.
Usually blow molding is done by inflating a heated, tubular piece of plastic with air so that it presses against the mold to shape it. The result is a evenly spread, thin sheet of plastic in that’s hollow on the inside.