About plastic injection molding

Plastic injection molding is among the best manufacturing methods. For example, it has proven to be very important in the consumer sector that mainly relies on plastics. Plastic injection molding can provide quality end products according to the demand by product development.

Injection molding refers to injecting high-pressure molten plastic material into a metal rod to make custom plastic parts. Afterward, the mold is cooled to produce solid plastic just like in the other forms of molding.

Plastic injection molding uses

The plastic injection molding technique is used mainly to produce a high number of custom plastic parts. So if you are planning on running a company that will need a high volume of plastic components then injection molding is the best option. Plastic injection molding machines are available in different sizes to handle different sizes of components.

For example, large machines can mold a bigger component to be used in things such as cars. On the other hand, smaller machines can make very precise components such as the ones used in surgical equipment.

The plastic injection molding process also consists of the use of man types of additives and resins that help in increasing flexibility. This allows engineers and designers to mold even the most complicated shapes easily. The plastic injection machines are very expensive and are usually made of aluminum or steel. Let us look at a brief description of the injection molding process.

Injection molding process

Product design

Product design is a very important step in the injection molding process because it helps in preventing making expensive mistakes. Also, it ensures that the objectives such as aesthetics, function, assembly, and manufacturability are achieved.

This stage is done with the help of Computer-Aided Design software. Besides, proficient CAD designers are required since they can be able to make more accurate prototypes or quicker iterations.

Mold design

After a feels like, looks like design has been cleared for further production, the next step is to design the mold for Injection manufacturing. The following materials are the most commonly used when it comes to making molds.

Hardened steel– This is the most expensive material but it lasts longer as compared to the others. So it’s more suitable where hundreds of thousands of products are being produced.

Prehardened steel- less expensive to create but does not last long like the hardened steel

Aluminum- best for single cavity prototype tooling especially when very few parts are required for testing.

Beryllium-Copper alloy-This materials were suitable for instances where fast heat removal is required.

Product design and mold design share one thing in common. That is they prevent expensive mistakes during the molding process. Furthermore, the number of cycles that are required to create a certain mold drives the decision of the most suitable method and material to use.

Manufacturing process

After a product undergoes the two stages above successfully, then it’s time for the actual manufacturing process to start. Let us look at some basics of this manufacturing process.

Thermoplastic or thermostat is fed into a heating barrel through a hopper in granular form. This plastic is heated according to the specified temperature and then it’s driven into the mold through the gates b a large screw. Also, the same screw is used to apply pressure after the mold has been filled until a given cooling time is over.

The screw is withdrawn immediately the time stops and the mold is opened. The gates can be removed manually or shear off automatically. This cycle is repeated over and over for a short time and very many man parts are produced.

What is TPU injection molding

TPU stands for thermoplastic polyurethane and it is a material that is used during injection molding to produce the most precise parts. Thermoplastic Elastomer TPE is material that is also used for the same purpose as the TPU. Besides, these two materials are classified under TPE which encompasses 6 materials that can be used commercially. These materials include:

  • Thermoplastic copolyester
  • Thermoplastic olefins
  • Thermoplastic polyamides
  • Styrenic block copolymers
  • Thermoplastic polyurethanes
  • Elastomeric alloys

Both TPUs and TPEs are energy efficient and hence they do not require compounding. So TPU injection molding is one of the best methods since it’s cost-effective. The following are some of the advantages of TPU injection molding.

Advantages of TPU Injection molding

The following characteristic exhibited by the thermoplastic polyurethanes is very beneficial when it comes to the injection molding process.

  • Energy efficient
  • Excellent colorability
  • No cure systems, reinforcing agents or stabilizers required
  • Little compounding is required and sometimes non
  • Improved consistency

TPUs are very important for a wide range of industries. Whether it’s for medical devices, consumer industries, or aerospace prototyping both TPE and TPU injection molding can be very useful.


Plastic injection molding is undoubtedly one of the best methods to manufacture plastic parts. Besides, this method can be used to produce man plastic parts in a very short time. The injection molding process involves the following stages i.e. product design, mold design, and the manufacturing process. These stages are very important because they help to prevent expensive mistakes and also speeding up the production process.