The Pros and Cons of Additive Manufacturing

Intro

Additive Manufacturing has become increasingly widespread since first emerging in 1987. In the past decade, lowering costs and technological advancements have led to a huge increase in uptake of 3D printing. Aerospike rocket nozzles, prosthetic legs and architectural models are only a handful of the huge variety of objects that have been successfully created with AM technologies. In the article we will discuss the Pros and Cons of Additive Manufacturing.

More recently, additive manufacturing has effectively provided rapid and vital solutions to the Coronavirus pandemic. Equipment including masks, valves and swabs that would otherwise be in short supply have been 3D printed.

As with any other technology, AM has it’s strengths and weaknesses. This can determine it’s applicability to a given manufacturing project. Here, we go through some of the most common advantages and disadvantages and how they could be relevant to different business cases.

Advantages

Allows for Rapid Innovation

3D printing provides a very rapid and fluid method to create prototypes. Once a product or part has been designed in CAD software, it is possible to immediately print a proof-of-concept very soon after. As there is minimal tooling involved, any changes or iterative improvements can be manufactured and tested immediately after they are implemented in the design.

This allows engineers to quickly create parts to be tested more rapidly than other more traditional techniques. It also allows architects to work with physical representations of their designs, and product designers to have their designs QA tested very rapidly.

In a recent survey, one of the main uses of 3D printing was prototyping and proof-of concept, and 80% of the surveyed companies stated that 3D printing helped them to innovate faster.

Reduces cost of small batch production

In addition to prototyping, additive manufacturing can be very well suited to manufacturing parts in small quantities. This is again due to AM’s minimal requirements for tooling and preprocessing.

Before 3D printing was a possibility, manufacturing small batches of complex parts was very expensive, especially in the aerospace industry. Bespoke components for aircraft and spacecraft required in relatively small numbers would be very expensive to produce per unit. Expensive tooling, such as the creation of moulds for injection moulding, is one of many factors that benefit from the economies of scale. Therefore, for small volumes they can easily dominate the cost of manufacture.

This is not the case for AM. Coupled with the ability to iterate designs quickly, this can reduce costs by an order of magnitude compared to subtractive methods.

More efficient use of material

More traditional fabrication methods, such as milling, drilling and lathe-turning, involve the removal of material from an initial volume to form parts and structures. Any material that is cut away is waste, and the more waste material there is, the higher the material costs will be per kilogram.

Clearly you want to use as large a proportion of the raw material as possible to minimize waste. This proportion is often called the buy-to-fly ratio in the aerospace industry. This is one of the areas AM has a clear advantage over other techniques.

Unlike subtractive manufacturing, AM builds up forms by continuously adding material. This results in minimal material waste, as only the amount required to constitute the part is used.

3D printing can also result in higher material efficiency by using complex geometry simply not possible with traditional techniques. By replacing solid sections with lattice structures, the University of Texas managed to use 42.4% less material using 3D printing. Many techniques used to further reduce material use, such as topology optimization, often produce designs only manufacturable through additive techniques.

Finally, AM techniques are very well-suited to re-manufacturing processes. An example is 3D printing weathered sections of a used part to restore end-of-life components. Such a process uses a fraction of the material that would be required to completely rebuild the part. Studies into applying this capability to more complex situations have yielded positive results

Disadvantages

High Cost-of-Entry for Industrial Production

While there are many cases where additive manufacturing is cost-effective, there are others where it can be prohibitively expensive. Cost-effectiveness is often dependent on material, business case and other situational factors.

Industrial-grade metal 3D printers can cost hundreds of thousands of pounds each, requiring significant initial investment. Due to their complexities and extended capabilities, there are also often significant implementation costs, including setup and training costs. As a near-net-shape processes with unique sources of imperfection, AM can also require further investment in expensive finishing hardware such as hot isostatic presses.

In addition to the initial purchase and installation costs, raw material costs can be more expensive than their traditional counterparts. Alloys such as Ti-6Al-4V can cost significantly more in the powdered form required for Laser Powder Bed Fusion (PBF) printers than their raw, unprocessed forms. Furthermore, secondary chemicals such as shielding gases for Direct Energy Deposition (DED) printing also need to be factored in.

Finally, 3D printing is still a relatively new and pioneering form of manufacture. Thus, there can be a significant investment in R&D required for companies working with materials in ways not common to the manufacturing process in question.

These expenses are often balanced out by the other benefits of additive manufacturing, but they are important to consider. For structurally identical parts, a suggested rule-of-thumb is that metal 3D printing is competitive with subtractive manufacturing methods if the buy-to-fly ratio for the latter is greater than 10:1.

Speed

Similarly to it’s cost-effectiveness, the timeliness of Additive Manufacturing is highly dependent on use case and batch size. While 3D printing can greatly speed up prototyping and overall time to production for small volumes, the actual process of printing a part can be slow compared to traditional counterparts. Plastic parts that would take seconds to make with injection moulding could take hours with a 3D printer.

This is important to factor when considering additive manufacturing for larger volumes.

Conclusion

As with any other manufacturing technology, additive manufacturing is more suited to some use cases than other ones. Through the examples above, it’s clear that the Pros and Cons of Additive Manufacturing are highly dependent on the situation and various case-specific parameters.

To find out if your business case could benefit from introducing additive manufacturing, get in touch.