15 injection molding terms :

Plastic injection molding process is a wide term and has its own terminology. There are hundreds of unique words associated with the process. However, to make everything easy and manageable, we have created a list of 15 injection molding terms that are very important to know.

15 most important injection molding terms-


Resin refers to the material that plays a crucial part in producing the final finished product. There are hundreds of commodity and Engineering resins available in the plastic injection molding industry.

injection molding terms-resin


The pigment can be in the form of pellet or liquid that is mixed with resin to produce a specific shade.

injection molding terms-colorant

3.Wall thickness

Wall Thickness is the most significant factor in determining the cost of production. The goal is to go for the thinnest wall possible.

4.Mold cavity

The hole in the mold that creates the desired shape is again an important part of the entire injection molding process. The lesser the cavities in a mold, the lower is the requirement of the tooling work. Also, the cost is less and high quality mold comes with maximum cavity.

mould cavity


The hollow part made up of Stainless Steel material or plastic is designed for mass production. Molds are made up with great accuracy and efficiency. They are meant to last for years.


Presses are classified on the basis of tonnage which signifies the exact clamping pressure a specific machine delivers. Press tonnage can be as low as 5 tons or as high as high as 4000 tons. Pressure allows to keep a mold closed during the injection process. If the pressure is very low, it can have a toll on quality and result in flushing. The appearance of the extra material on the edge part determines the exact size press for the application.

7.Electric presses

The electric presses have been existing back since 1983. The latest electric press technology is easy to operate and has better accuracy. These machines are empowered with digital control high speed Servo Motors instead of Hydraulics. Energy efficient operation every time so that a desirable injection process can be executed.

8.Flash and burrs

Flash and burrs are the terms used interchangeably. Flash is created because of excessive injection speed for a pressure. They are also the result of high mold temperature or excessive barrel heat.

9.End of ARM tooling

Higher the efficiency and speed of the injection molding machine, better are the cost Savings. Undoubtedly, robots play a significant role in enhancing the speed of the manufacturing process. End of arm tooling is an advantageous process that uses sensors and pneumatic to reach a specific process.

10.Runner system

It refers to the channel system that helps to ease the flow of melted material to fill the path cavities.

The below other 5 key injection molding terms are much important :

11.Hydraulic process

The most common type of process used in the plastic injection molding process includes machinery that has hydraulic cylinders to bring together two halves of a mold with high pressure.

12.Hybrid process

Hybrid injection molding machines are made available in the market since few decades. They provide superior clamping force and greater Precision. There is reduced noise of an electric machine which also results in a better operation and performance. Hybrid machines have increasingly become popular in the past few decades because of their higher efficiency.

13.Hopper and barrel

The Hopper is a repository of plastic and plays an important role in the injection molding process. A Hopper also consists of a small magnet to prevent any harmful metallic particles from getting inside the machine. The plastic material placed in the Hopper comes in the granular form. Eventually, it is melted using heat and then injected through the nozzle inside the mold cavity. Using the Hopper, the pellets are fed to the barrel where the material is melted and injected in the mold machine.


It is defined as a distortion in the injection molded part, often caused by residual stresses and differential shrinkage during the cooling process.

15.Shrink Rate :

Ranging from 0.001-0.060 per inch, shrink rate is defined as the rate at which the injected plastic will shrink once it is cooled.


Hope you have found the key injection molding terms very useful.If you are into molding industry these terms are very essential to understand. Without the basic understanding of important injection molding terms,it will be very difficult for you to take the decisions when purchasing injection molding machines or molding materials for your business.

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