Injection Molding vs Extrusion Molding: Difference and Comparison

Both the terms injection and extrusion moulding are the processes used for manufacturing different types of 3D or 2D products. Both processes have their advantages based on their manufacturing.

The process of injection moulding is a type of manufacturing process which includes squeezing the liquid plastic into a mould which further becomes hard. This process is a bit complicated as well.

On the other hand, the process of extrusion moulding is a type of process in which molten plastic or any other material is pushed through a 2D die opening, and as a result, linear shapes are produced.

Let us discuss the difference between the two methods of moulding in detail.

Key Takeaways

  1. Injection molding uses high pressure to force molten material into a mold cavity, while extrusion molding pushes material through a die to create continuous, fixed cross-sectional shapes.
  2. Injection molding is suitable for producing complex, high-precision parts in large volumes, whereas extrusion molding is more cost-effective for simpler, continuous profiles.
  3. Extrusion molding results in lower tooling costs and faster setup times, while injection molding offers greater design flexibility and material options.

Injection Molding vs Extrusion Molding

Injection moulding is a process used to produce small to medium-sized plastic parts with high accuracy and repeatability. Extrusion moulding involves melting plastic resin and forcing it through a die to create a continuous profile. It is commonly used to produce long, continuous products such as tubing, pipes, and sheeting.

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In injection moulding, the process of manufacturing products is based on the molten die-casting method. It helps in the production of 3D products.

This process was fully established in the year 1930. Compared to any other process of moulding, injection moulding is a bit complicated method to perform.

Extrusion moulding is a manufacturing process involving transferring the molten material through a die cavity to form an extruded shape.

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This process is known to be invented by Thomas Hancock in the year 1820. This process is only applicable got seamless product manufacturing. With the help of this technique, pipes, tubes etc., can be manufactured easily.

Comparison Table

Parameters of Comparison  Injection Molding Extrusion Molding 
Specification This process enables manufacturers to use multiple types of plastic resin which also includes recycled materialsThe process of extrusion allows for additional fabrication and alterations to the product
Suited for  It helps in the production of 3D products  It is preferrable for producing 2D products  
Advantage The most important advantage of plastic injection is that it allows easy creation of three-dimensional plastic products and the process works relatively quickly and captures the complexities of the mold as well.The benefit of extrusion molding process is that the dies create very smooth finishes that are ideal for many products like pipes, straws and other commonly used products.
Can manufacture  It is suitable for manufacturing products like plastic bottle caps, syringes etc.  This process is suitable for the production of door frames, seals, pipes etc.
Cost Due to the requirement of costly dye, the process of injection molding is a bit expensive method This process of molding is not very expensive as compared to injection molding

What is Injection Molding?

The process of injection moulding is a process that is always preferred for small containers or products.

This process is performed by injecting and then re-heating the material, which is further stretched for greater strength, and then the product is blown into moulds.

The steps involved in injection moulding start with collecting the resin pellets, which will be manufactured and placed in the hopper.

The pellets are fed by the hopper with the help of a compression zone in which friction is created, which in return creates heat so that plastic can be melted.

Further, the plastic in a molten state will pass through a small nozzle into a mould-like structure. Now the plastic will fill the mould and take shape as well.

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When it gets cooled and becomes hard, the 3D shape will be taken by the plastic.

What is Extrusion Molding?

The process of extrusion moulding is used for making parts of a continuous length and uniform cross-section.

The plastic products produced by this process have high melting viscosity, this allows the extrudate to retain the shape which has been imparted to it by the dye while the extrudate is in the stage of quenching.

The shape of the obtained cross-section varies, and it can also be manufactured according to your needs, such as a rectangle, L or T shape, solid round shapes etc.

The extrusion moulding process has an edge overdrawing as it uses a type of stress which is compressive and allows large deformation. This process also produces comparatively weaker products.

The most suitable material for extrusion moulding is thermoplastic. Materials that have very high strength and stiffness in the molten form are also considered very convenient.

The extrusion moulding process is suitable for manufacturing 2D products and is a very new process.

Main Differences Between Injection Molding and Extrusion Molding

  1. The process of injection moulding is suitable for manufacturing 3D products, on the other hand, extrusion moulding is suitable for manufacturing 2D products.
  2. The process of injection moulding is a very old process of plastic manufacturing, whereas extrusion moulding is a new process.
  3. Using injection moulding ensures the products’ strength, and extrusion moulding produces comparatively weaker products.
  4. The process of injection moulding is quite expensive as it requires costly dye. On the other hand, extrusion moulding isn’t that expensive.
  5. Injection moulding is a bit more complicated method as compared to extrusion moulding.
References
  1. https://www.sciencedirect.com/science/article/pii/S093964119900034X
  2. https://www.sciencedirect.com/science/article/pii/S0022354915300745

Last Updated : 11 June, 2023

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10 thoughts on “Injection Molding vs Extrusion Molding: Difference and Comparison”

  1. The article succinctly lays out the differences between injection and extrusion molding. A great resource for those wanting to understand the processes.

    Reply
  2. The process differences are clearly explained, but extrusion molding’s weaker products should be discussed further to clarify their applicability. More depth is needed.

    Reply
  3. Very informative article that clearly distinguishes between the two types of moulding. Thank you for the details!

    Reply
  4. The article provides a comprehensive comparison between injection and extrusion molding, perfectly catering to a reader like me who’s looking to explore these manufacturing processes.

    Reply

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