What is Injection Molding?

Injection molding is the most commonly used manufacturing process for the fabrication of plastic parts. A wide variety of products are manufactured using injection molding, which vary greatly in their size, complexity, and application. The injection molding process requires the use of an injection molding machine, raw plastic material, and a mold. The plastic is melted in the injection molding machine and then injected into the mold, where it cools and solidifies into the final part.

Common Applications

Medical Devices
Automotive Parts
Textile Spare Parts
Consumer Products

How Does Plastic Injection Molding Work?

The injection molding machine is made up of three main components, which are the feed hopper, the screw, and the heated barrel. This machine works by taking plastic powder or granules and manipulating it to shape it into a part according to the requirements and dimensions. When the feed hopper receives the plastic granules, it then uses frictional action of the screw to create heat. Once the plastic reaches the correct temperature, it is then injected into the mold cavity, where it eventually cools and takes the shape according to the mold design.

Benefits Of Plastic Injection Molding

One of the primary reasons why injection molding produces consistent results is that a lot of the actual manufacturing process can be automated. That means that you can not only reduce the chances of human error to a minimum, but also have the machine produce parts at a consistent rate and a high fulfillment rate.
For the most part, injection molding is one of the most cost-effective solutions for producing parts that you can find. Even though the bottom line of your project will depend on the materials that you use and the complexity of the designs, when comparing it with other manufacturing methods, you will usually find that injection molding will deliver more for the budget that you can allocate.
If there’s one thing that injection molding really excels at, it’s the ability to customize the materials and finishes according to almost any type of requirements. You can choose plastic, thermoplastic rubber, chemical resistant plastics, biodegradable, and many others, so just be sure to figure out what you need from the part and you’ll have plenty of options. You can also select almost any color imaginable, and can also choose from a wide variety of finishes, either for aesthetic or functional purposes.
Injection molding enables companies to produce even the most complicated mold designs, executing even the smallest of details with ease. You can add multiple details to your mold design and rest assured that each of them will be made a reality by the mold.
Because of the way that material is injected to and then shaped by the mold, the number of imperfections can be reduced to a minimum. That means that with every run, you can produce a part that is identical to the one preceding it, over and over again. As you can imagine, this type of precision is important in almost all industries, and especially in those that can’t compromise on quality, which is why injection molding is popular in highly-demanding fields like aerospace and automotive.
Unlike most other production methods, injection molding provides advanced possibilities in terms of the durability and reliability of the plastic parts that are produced. For instance, you can add fillers in the injection molds that are created, which can help reduce the density of the plastic material and make each part stronger.

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Plastic Injection Molding Materials

There are many types of materials that may be used in the injection molding process. Most polymers may be used, including all thermoplastics, some thermosets, and some elastomers. When these materials are used in the injection molding process, their raw form is usually small pellets or a fine powder. Also, colorants may be added in the process to control the color of the final part. The selection of a material for creating injection molded parts is not solely based upon the desired characteristics of the final part. While each material has different properties that will affect the strength and function of the final part, these properties also dictate the parameters used in processing these materials.


Polyethylene (PE) is the most popular plastic in the world, and accounts for 34% of the total plastics market. There is low-density polyethylene (LDPE) and high-density polyethylene (HDPE). LDPE is manufactured with high pressure and high temperature, whereas HDPE is manufactured with relatively low pressure and low temperature.So be sure to considering LDPE injection molding or HDPE injection molding with your next project.
Polypropylene (PP) is the second most widely-produced plastic in the world, after polyethylene (PE). Its behavioral characteristics are similar to PE, but it is slightly harder and more heat-resistant. It is a commodity grade polymer popular in the packaging and labeling industries. PP is tough, fatigue- and chemical-resistant, but vulnerable to UV radiation and it is flammable. It is a versatile plastic, as it is easily customized with additives. It is naturally white. Due to the elasticity of PP, it makes a good material for living hinges. It is also used in many common items such as buckets, packaging, bottle caps, toys and many other items.
Acrylonitrile butadiene styrene (ABS) is also one of the most common, widely-used plastic material in the world. ABS plastic molding is often a standard when it comes to mold making. Impact resistance and toughness are the two most important material characteristics of ABS, and those qualities make it such a popular, low-cost, commodity-level thermoplastic polymer. It is used in a wide range of products in the automotive, appliance and electronics industries, among many others. ABS provides superior strength and temperature resistance. It combines the strength and rigidity of acrylonitrile and styrene polymers with the toughness of polybutadiene, a rubbery material, even at low temperature. The styrene gives the plastic a shiny, colorfast, high-quality surface finish. ABS molding is on direction to consider.
Polyoxymethylene (POM) is also commonly known as acetal, and also known as polyacetal and polyformaldehyde. It is considered an engineering grade thermoplastic, a step up from commodity plastics in performance and price. It provides high stiffness, excellent dimensional stability, and is used for precision parts requiring low friction. POM provides high strength, rigidity and hardness, and it is resistant to chemical solvent. It is opaque white in its natural state, but it is easy to color to any color. POM is a good choice for high-performance components like small gears and bearings, and other applications where the component comes in contact with other parts, such as plastic gears and ball bearings. It is commonly used in the automotive and consumer electronics industries, and it is used in eyeglass frames, guns, knife handles and other items that require strength and toughness.
Polystyrene (PS) is a widely-used polymer that can be either solid or foamed. As a solid, it is used to make things like disposable cutlery, and in its foam state (Styrofoam) it can be extruded to make things like packing peanuts and disposable drinking cups. PS is clear, hard, and fairly brittle (think of how easily the tines can break off of a plastic fork). It is naturally transparent, but can be colored with colorants. It is not biodegradable, so many PS items, especially “single-use” items, contribute to the world’s litter problem. It is also used to make CD jewel cases, license plate frames and plastic model kits.

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