Chris van Dam guides us through the factors to consider when deciding whether Additive Manufacturing / 3D Printing is an appropriate alternative for your production process.
In my March 2022 article for The Metal Magazine, I discussed how Additive Manufacturing could disrupt certain sectors of the manufacturing industry.
I still strongly believe that additive manufacturing can be hugely beneficial in being used to produce more complex parts with far less waste material. In September 2022, NASA will be launching their latest Moon mission with a rocket that contains numerous 3D printed parts. But additive manufacturing isn’t just reserved for multi-billion dollar space agencies, and all sorts of benefits exist for manufacturers of all sizes.
In this article, I will discuss some of the factors that you might consider in order to evaluate whether additive manufacturing could be used in your own business. I will focus on metallic products, as that is my area of expertise, but some of the factors could still apply in additive manufacturing with other materials.
As designers push the boundaries of engineering possibilities, they no longer need to be constrained by the limitations of traditional manufacturing tools or techniques, and can design highly complex parts and intricate shapes that would never have been possible before.
The parts produced through additive manufacturing processes can be optimised to be lighter and stronger than their traditionally-manufactured counterparts, resulting in more durable and more efficient products. Load-carrying structural elements that unavoidably contain some non-load-carrying material due to manufacturing limitations (referred to as “dead weight” in aerospace) can now be further optimised by eliminating this excess material while maintaining structural strength.
Often it is possible with additive manufacturing to combine the function of several conventionally-manufactured parts into one element. Reduction of the number of parts means fewer joints and fewer possible points of failure, resulting in longer life cycles and (in certain cases) improved safety.
Due to the nature of additive manufacturing, which is an iterative, layered process, products are created with different mechanical and thermal properties in three spatial directions. This is called anisotropy, and it may be used to further optimise parts and fine-tune their properties.
Some of the negative points to consider include the fact that 3D printed parts are currently only capable of being produced with relatively small dimensions, due to the use of powder-based feedstock and the limited size of the building chambers in the currently available additive manufacturing machinery.
Another drawback is that the nature of producing the parts in layers can result in a rough surface on the finished product, when compared to other techniques such as CNC milling, for example. In cases where the rough surface is unacceptable, post-process treatments such as polishing are necessary.
The repeatability of quality in additive manufacturing is also still a concern, with occurrences of identical products being produced with slight differences on different production runs.
However, as is the case with their conventionally manufactured counterparts, mechanical properties may be enhanced and fine-tuned by post-processing such as heat treatment.
In many cases, the materials suited for additive manufacturing are way more expensive than stainless steel. For example, titanium and its alloys are roughly 60% to 100% more expensive than high-quality stainless steel. When you also factor in that many – particularly the high-end – applications require powder as the feedstock, the raw material cost increases further.
As powders become more widely available and new powder acquisition methodologies are developed, the cost of powdered raw materials will decrease.
Another important parameter to consider is batch size. Additive manufacturing tends to be more suitable for smaller production runs. Unlike conventional manufacturing methods, production time – and thus, cost – decreases only very slightly, if at all, with increasing batch sizes in additive manufacturing. This can be beneficial too, of course, if only smaller batches are required.
Hardware costs for additive manufacturing machinery vary greatly. The simplest units can be acquired for less than €100k, but these are generally not suitable for serious production and are intended for laboratory-scale and R&D purposes. On the other end of the spectrum, multi-million Euro units are available to perform large-scale production runs and manufacture of very complex parts. Modular systems are available, too, which means you can start small and then grow as your business expands, adding functionality such as robotic handling or heat treatment for post-processing later on.
Production speed tends to be slower than conventional subtractive manufacturing technologies, although this is improving rapidly. Multi-laser building chambers, for example, enable simultaneous production of multiple parts, or more rapid production of a single part.
One of the biggest benefits of additive manufacturing, in my opinion, is that it enables an extremely high conversion rate of raw material to end product, with the manufacturing process producing near-net-shape parts with very little waste. Also, in many cases, any excess powder can be recycled and reused, reducing waste even further. Conventional manufacturing techniques tend to yield substantial amounts of waste and scrap material, causing significant financial, logistical and environmental challenges.
It is said that with additive manufacturing, “complexity comes for free”. By that, we mean that complex products are no more expensive to manufacture than simpler ones, and the production cost is more directly related instead to the weight of the final product.
I would consider, therefore, that additive manufacturing is a much more ‘green’ technology. Not needing to transport excess raw material or waste reduces the environmental footprint. The production process tends to result in the emission of fewer, if any, toxic materials, and it has been demonstrated that additive manufacturing requires less energy and reduces CO2 emissions.
If you are a designer, manufacturer or end-user of metallic parts, I believe that the technology involved in additive manufacturing has developed to such a level now that it can be seriously considered as an alternative to many conventional manufacturing techniques.
Economically, it can compete with traditional methods for certain parts or processes, and technically it offers numerous advantages – such as the ability to produce lighter, stronger, more complex parts – that you may consider outweigh the economic drawbacks.
In the aerospace industry, where every gram of weight saved results in fuel savings and reduced CO2 emissions, producing complex parts using additive manufacturing processes can provide valuable efficiencies. Increased production costs may be offset by savings elsewhere further down the line.
As technology continues to develop, batch size capabilities increase and production costs decrease, additively manufactured parts will become more and more viable for more types of products.
I would urge you to look at the opportunities within your business to consider alternative production methods and designs, and reach out to the manufacturers of 3D printing machinery so that they can demonstrate their capabilities.