What type of plastic is used for injection moulding?

April 15, 2022


What type of plastic is used for injection moulding? In principle, the injection molding process (also called injection molding process/injection molding) consists of 5 individual steps. This is a so-call forming process. The accuracy of the manufacture of injection molded parts is what makes it so popular.

  • Plasticizing by heat

The granules are liquefied by heat, the mold is closed

  • Injection

Plasticized (liquid) plastic is “injected” into the mold at high pressure.

  • Repress

In this way, the shrinkage of the plastic (caused by cooling) compensates for the plastic that continues to flow.

  • Cooling down

Furthermore, the mold cools with water from the inside. This cools the plastic & makes the component dimensionally stable.

  • Demoulding

The tool opens and the plastic part is removed.



The quality of the injection mold is crucial for the result. Aluminum tools are often cheaper to buy. Unfortunately, these can withstand significantly fewer injection cycles than molds made of steel.


What type of plastic is used for injection moulding? Which of the two versions is the right choice can be easily calculated by taking into account the number of pieces to produce.

Due to the comparatively high acquisition costs of the mold, the injection molding process is only worthwhile for a certain number of items. However, large quantities can manufacture very economically thanks to the long service life of the injection molding tools. For small quantities, a choice of 3D printing can also be worthwhile.

A precise flow of the process

What type of plastic is used for injection moulding? Eventually, there are many entrepreneurs who are already very successful in marketing their own plastic products. Just imagine the ways you can use this process to create products that help make the world a better place.

Technical basics of plastic injection molding

Eventually, plastic injection molding is one of the primary manufacturing processes in which a defined shape produces from a shapeless mass by creating material cohesion. This process group also includes extrusion, which closely relates to plastic injection molding.

What type of plastic is used for injection moulding? In addition, injection molding is a cyclic process for producing workpieces with a specific geometry; extrusion is a continuous process for producing endless profiles. During extrusion, the plasticized plastic is not injected into a close mold but pressed through a die.

Moreover, in plastic injection molding, the raw material – usually in the form of granules – is first heated and plasticized in a screw cylinder. The plastic mass is then pressed into the tool with high pressure. This then cools in order to solidify the melt and finally remove the finished workpiece.

The most common methods for processing plastics include the following:

  • Archetypes
    • Injection Molding
    • Extrude
  • Reshape
    • Deep Drawing
    • Bending Forming
  • Put
    • Welding
    • Adhere

Rubber and silicone parts

What type of plastic is used for injection moulding? Due to the high cost of manufacturing injection molds, the process can hardly use economically in the production of prototypes and small series.

Construction of an injection molding machine

The plastic injection molding process

In addition, the injection molding machine largely automatically coordinates the cyclical process sequence described using the process variables. The determining factors for the settings on the machine are:

  • Plastic used
  • Design of the mold (number and size of the cavities, wall thickness)
  • Machine (locking force, stroke volume)

Special variants of plastic injection molding that require individual process management include:

  • Injection molding of inserted parts
  • Back injection molding of an inserted carrier part
  • Creation of cavities in injection molded parts
  • Injection molding of foam parts

Plastic injection molding machine

What type of plastic is used for injection moulding?  Different types of plastic place individual demands on the temperature control of the tool. The injection molding of a thermoplastic describes here as an example:

Plasticizing and Dosing

Subsequently, at the start of the injection molding cycle, the mold is open, and a dosed mass volume is present. The molding compound creates when the plastic granules draw in from the funnel by a screw and melted. 

As well as, the material plasticizes by the effect of heat in the heat screw cylinder. The screw transports the material into the front part of the cylinder, where it collects behind the nozzle. This creates a dynamic pressure that causes the screw to move backward.


What type of plastic is used for injection moulding? With the mold now closed and with a sufficient amount of melt between the nozzle and the tip of the screw to fill the mold, the injection can take place. To do this, the axially displaceable screw presses the plastic mass into the mould. Furthermore, the pressure increases to a maximum value during filling and then gradually decreases.

What type of plastic is used for injection moulding 2022

Press and Cooldown

What type of plastic is used for injection moulding? Moreover, the pressure maintains in order to be able to compensate for the shrinkage of the solidifying melt. The mass cushion remaining in front of the screw tip can thus flow into the mold. This is to avoid common mistakes in injection molding: sink marks and blowholes. The tool cools to speed up the cooling process of the molded part.

Demould and eject

What type of plastic is used for injection moulding? In addition, the tool for ejecting the solidified injection molding can now be opened. The workpiece falls out of the mold or is removed by a handling device. The sprue that does not belong to the molded part can then removes manually or automatically.

Which materials can be processed?

Plastic injection molding is suitable for processing all types of plastics:

  • Thermoplastics
  • Thermosets
  • Elastomers
  • Thermoplastic Elastomers

The different polymers require different temperature control of the tool. The injection molding of thermoplastic materials, especially polyethylene, is of the greatest economic importance.

Advantages of plastic injection molding

What type of plastic is used for injection moulding? The advantages of plastic injection molding are:

  • High reproducibility of production
  • Little or no post-processing of the molded part is necessary

Besides, the workpieces produced during injection molding can often use without further reworking. Accordingly, the direct route from the raw material to the finished part contributes to the attractiveness of the process.


What type of plastic uses for injection moulding? Injection molding uses for the production of small series and offers a high level of efficiency with complex, small tools compare to lengthy, conventional production.

Furthermore, we offer short manufacturing times and consequently lower final manufacturing costs. Injection molding also produces series-identical precision parts.

Lastly, the injection-molded parts do not have to rework, only rarely. After the tooling for the injection molding and the installation of all components, the process runs automatically – so there is no need for constant monitoring.


Get A Quick Quote