Knowledge Hub
16/09/2023
Additive Manufacturing vs Injection Moulding
In our two recent technical articles, we investigated additive manufacturing and injection moulding. We explored them as two very distinct processes which are aimed at achieving the same thing…. the creation of plastic components for prototyping or low-medium volume production.
We will now look to summarise what we have learned from our examination into additive manufacturing and injection moulding.
We will also highlight the key advantages and disadvantages of both methods.
Injection Moulding
Injection moulding refers to the manufacturing process of producing parts by injecting molten material into a mould. The material, often plastic, is injected into the mould cavity in order to create a part. Once inside the mould, the material quickly cools, and the part takes its final solid shape.
Additive Manufacturing
Additive manufacturing is the process of creating parts by adding layers of material. Using this process, there is no need to create a mould to produce a part. The part is made by creating a CAD file which then talks to a machine and adds material until a part is formed.
Let’s look at the key parameters of both methods, examining in more detail the specific pros and cons associated with each process.
Injection Moulding
Pros:
- Advantageous if large volumes are required
- Produces parts that are high in precision
- The process allows for great ease of repeatability
- Extensive choice of materials with different properties
- Highly suitable for mass production
- Generates production intent parts from the tooling, making them ideal for market testing
- Low cost per part. This is particularly useful in circumstances where parts will need to be run off the existing tool at regular intervals over a sustained period of time
- Greater scalability: can produce low volume prototype parts through to tens of thousands
- Ideal process for components that require high detail
- Parts produced often have greater strength and durability
- More suited to larger components than additive manufacturing
- Perfect choice for bulk production
- Results in a better product surface finish
- Improved functional integrity of parts, which are more visually appealing and reliable
- Most plastic used during this process can be reground, recycled and reused
Cons:
- Up-front capital investment in tooling can be prohibitive
- This process can result in higher amounts of plastic waste
- Increased project turnaround times
- It can be challenging to change tooling to optimise or iterate new designs
Additive Manufacturing
Pros:
- Ideal for rapid prototyping as this process allows for quick and easy production runs
- Works well for low volume production runs
- Ideal for complex or intricate component designs where detail is important
- Low entry costs and reduced material costs
- Suited to projects where the design goes through several iterations
- Highly flexible and agile process which ensures precision of final design
- Modifications can be made easily using 3D modelling software
- Time and cost savings can be achieved where there is no requirement to build a tool
- Produces less material waste
- Parts produced may be more ergonomic
- Reduces inventory and storage burdens as there is no tooling that needs to be housed
- Increased digital inventory reduces carbon footprint and improves sustainability credentials
- Manufactures directly from 3D CAD files so the location of manufacture is more flexible
- As it is a digital process, it can be stopped post-part build or post-run, and restarted with punitive cost
Cons:
- Suitable for small plastic parts or components, but there are limitations with larger products
- Unsuitable for large volume production runs
- This method doesn’t allow for printing in production intent grade material
- Surface finishes can be problematic, often creating a ridged surface, which can be an issue when producing parts that will rub against one another
- Despite the initial set up being quick, the overall process can be slow, as most printers can only build one item at a time, which creates a significant challenge for detailed designs
Summary
Additive manufacturing and injection moulding are two very distinct processes with a range of advantages and disadvantages associated with both methods.
Additive manufacturing is ideal for very small production runs and offers quick turnaround times. Changes to the designs can be made easily and it is a process which suits the production of relatively small components.
Injection moulding is ideal for parts of all sizes and can accommodate prototype, pre-production, and production volumes. The costs are low per part and the process allows for ease of repeatability.
Choosing the right process is dependent on the end application of the component. Knowing how the product must look and function will usually determine which process a customer chooses. Such factors might include smoothness of finish, strength and durability, and heat or pressure resistance.
Industries that are highly regulated, and in which product safety and liability is a key factor, such as the aerospace and consumer goods sectors, may also dictate which process is most suitable.
However, it is worth noting that although this article has explored these two processes in direct opposition to one another, some now argue that both practices can occupy a common ground.
Indeed, many manufacturers and product engineers now regard additive manufacturing and injection moulding as complimentary rather than competing technologies. Combining these techniques can reduce pre-production cycles and allow for better testing and manufacturing.
To Find Out More:
If you’re about to embark upon a project and would like to know more about injection moulding, please contact us at info@rptechnologies.co.uk, or call +44 (0) 121 550 5868, and we will be happy to discuss your requirements.
