What Is the Plastic Injection Molding Process? Everything You Should Know

Plastic makes up around 50% of a car’s body, but only 10% of the weight.

You’ll find plastic in every vehicle because it’s lightweight, flexible, inexpensive, and rust-resistant. Plus, it’s easy to mold using plastic injection.

The plastic molding process plays an essential role in the creation of plastic parts throughout many different industries. From pharmaceuticals to telecommunications, plastic parts exist in most products.

Are you curious about the plastic molding process and how it works? Keep reading for a breakdown of plastic molding.

What Is Plastic Injection Molding?

Injection molding is a manufacturing process. It entails producing parts by injecting a mold with molten material. Several elements, such as glasses, confections, elastomers, and metals makes up the process.

More commonly, injection molding uses thermosetting and thermoplastic polymers.

The plastics fabricate items and parts to be used in toys, automotive parts, water bottles, containers, and plenty of other components and products we use daily.

Plastic Used In Injection Molding

Different plastics used for injection molding…

Polycarbonate, for example, is exceptionally durable and has impressive optical properties. It has both uniform and predictable mold shrinkage and is significantly stronger than acrylic.

It contains BPA, so it is not suitable for food preparation and storage.

Polyoxymethylene is highly resistant towards solvents like gasoline, motor oils, and alcohol. Durable, rigid and used creating automotive parts that would otherwise be metal.

For reliable mechanical parts, many automotive gears, bearings, and bushings get produced using nylon, also known as Polyamide (PA). It has a high melting temperature, it’s tough, and it boasts strong chemical resistance.

Polypropylene (PP) exists throughout the packaging and food storage industry. The thermoplastic material does not allow chemicals to mix with food products. It can be washed in hot water without breaking down, and it is highly resistant to moisture and chemicals.

PP is strong and has an excellent elasticity.

Polyethylene is a thermoplastic with high chemical resistance. Plus, it boasts electrical insulating properties and elasticity. It’s not particularly strong, though.

Polyethylene is the most widely used injection molding plastic for children’s toys. Also used within milk bottles, medicine bottles, detergent bottles, trash cans, and plastic bags.

Acrylic is thermoplastic made without Bisphenol A (BPA), the harmful organic synthetic compound not suitable for food storage and preparation.

Acrylic has a high tensile strength. Plus, it’s scratch-resistant and weather-resistant. It has many unique qualities, such as being odorless and tasteless. It also boasts optical and transparent properties.

How Does Plastic Injection Molding Work?

Before plastic injection occurs, an experienced molder must first make a mold. The mold includes two parts, a core, and a cavity. It contains the exact features and geometry required as per the product specifications.

Once the mold exists, loading within the plastic injection molding machine begins.

There’s a hopper that holds thermoplastic pellets of the plastic required for the specific mold. Those pellets get fed into the main barrel of the plastic injection molding machine.

The barrel melts the pellets, and then either electric or hydraulic toggles close the mold halves. The toggles press the mold parts together with hundreds of tons worth of pressure. Once the thermoplastic enters the mold, it starts to cool and then solidify.

It conforms to the mold’s shape. When finished, the frame opens, and ejector pins eject the product or part from the core.

Here’s a quick recap of the steps necessary for creating a plastic injection mold:

  • Thermoplastic enters the barrel
  • The plastic melts and mixes
  • Mold halves close with great pressure
  • Plastic injected into the mold cavity
  • The material cools
  • Once cooled and solidified, the mold opens
  • The part ejects

How to Make a Plastic Mold for Injection Molding

Are you wondering how to make a plastic injection mold in the first place?

A plastic injection mold begins with a hollow metal block with cavities. Multiple holes within the mold realize the temperature control.

A sprue allows the melted thermoplastic to flow into the mold. Through the runners and gates, the cavities fill up. Once the mold cools, the mold opens up, and the molded parts eject.

What Are the Benefits of Plastic Molding?

Plastic injection molding is very efficient. Depending on the complexity of a specific mold structure, the process only results in an interval of 15 to 30 seconds between each cycle.

The highly accurate process can be used to create diverse classification of perfectly molded plastic parts.

The process requires minimal human supervision, making the process streamlined, continuous, and inexpensive.

Plastic is less dense than metal and is cheaper to buy and produce. Plastic is extremely flexible, too, so it’s easy to switch up material types and colors for production once a mold is made. It’s easy to alter a mold for product modifications as well.

Plastic injection molding is effective, efficient, and resourceful. Unused materials are recycled, and then attention is given to sustainability.

What Industries Use Plastic Molding?

Injection plastic molding plays a part in a variety of industries. Telecommunications, for example, uses all sorts of specialized plastic parts integrated throughout fiber-optic networks.

From eye droppers to syringes, the pharmaceutical industry uses uniform, sterilized, high-quality plastic parts. The pharmaceutical industry is on the rise, so we’ll continue to see more injection plastic molding throughout their products.

Transportation, automotive, medical, and consumer product industries all take advantage of plastic molding products.

Hire the Best Plastic Injection Molders

Plastic injection molding is a fantastic process that aids in the manufacturing of many products and tools we use daily. Plastic injection molding is flexible, durable, and versatile.

Plus, the process continues to become more sustainable as any leftover materials get recycled and saved for use for another product or mold.

If you’re looking for a plastic injection molder, make sure they have the expertise and knowledge to help with your product. Are you ready to request a quote?

So, contact us today. We are up to any challenge!

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