Spotlight – A snapshot of additive manufacturing

Materials World magazine
,
1 Jan 2018

A snapshot of additive manufacturing – technology, materials and industry

Dr Martin Baumers, Assistant Professor of Additive Manufacturing Management at the Centre for Additive Manufacturing, UK, takes a look at the industry and the materials it uses.

What is additive manufacturing?

Additive manufacturing (AM), also known as 3D printing, has gripped the imagination of engineers and manufacturers in many different sectors. As an inherently digital manufacturing technology. It is regarded by many as a means to manufacture on demand, realise new product designs and adopt novel supply chain strategies. Defined as manufacturing technology that joins materials in a layer-by-layer fashion, it should be noted, however, that the label of AM actually forms an umbrella term for a multitude of technologies. These technologies can differ quite significantly in operating principle, performance, build materials, costs and scope of applications.

Is AM simple?

What is clear is that AM, since it never involves physical tooling such as moulds, is a relatively unrestrictive technology capable of delivering complex product designs and highly customised products. The flipside of this design freedom is what the community refers to as a large parameter space. The successful implementation will require the user to control many different aspects of the process, including the conversion and processing of digital design data, the composition of builds, the orientation of products and the settings and state of the machine. This extends to additional aspects surrounding the core process, such as raw material handling, initial post-processing and product validation. This implies that, perhaps contrary to expectations, industrial AM processes require careful implementation and significant expertise.

Which materials are used in AM?

AM technologies are designed for specific material classes – including various polymers, metals and ceramics. Within each technology variant, a small number of materials are usually dominant. The table below lists a selection of important materials within each AM technology type.

What is unusual about AM materials?

The forms of raw materials used are varied, ranging from powders, wires and filaments to oligomeric resins. While it is hard to make generalised statements, in the majority of cases, AM materials must conform to tight specifications imposed by the process. For example, powder-bed fusion processes will normally require that particles are spherical, do not exhibit internal porosity and have an appropriate size distribution around a process-specific mean. Similarly, the filament materials used in extrusion processes require a high degree of circularity for the process to operate reliably. Material properties as-deposited due to the highly sequential layer-by-layer process are unlike those resulting from more conventional manufacturing processes. For example, with metallic AM processes, the resulting material characteristics may depend strongly on the orientation of the part, known as anisotropy. Another example would be the fatigue behaviour of parts made via material extrusion processes which may suffer from delamination effects occurring between different horizontal layers.

How are AM materials bought?

The raw materials used for AM are normally supplied through one of three different procurement channels. First, raw materials can be obtained directly from the technology vendor or local agents. This has the advantage that the supplied raw material meets the requirements of the machine and is ready to use. It is important to keep in mind that the technology vendors do not normally produce the raw material – the disadvantage of this option is that prices may include a significant mark-up. 

Second, AM materials can be bought directly from the material manufacturers. This opens up a wide range of possible materials and characteristics and may be beneficial in terms of cost. However, the materials procured in this way have not been validated by the AM technology vendors, which may lead to quality problems, build failure and also withdrawal of support. 

The third option is procuring AM materials from specialist independent suppliers and stockists. While providing a degree of validation and ease of sourcing, this route may also suffer from relatively high costs and a lack of support from the technology vendors.

What is the price of AM materials?

It is generally accepted that AM materials are expensive when compared to conventional bulk materials of a similar type. For polymers, a 2014 comparison has estimated that price multipliers range from 10–470 times, suggesting that the surveyed AM materials can be many times as expensive as their conventional counterparts. For metals, the price multipliers are somewhat smaller but still significant, ranging from two–27 times. The high prices may be explained partly by the cost of incorporating the characteristics needed for AM. A further factor is the small size of the AM industry compared to other raw materials industries, forcing providers to charge higher prices to cover the costs of small-scale processes.

Where is the AM materials industry headed?

Over the recent decades, the overall AM industry, including products, services and materials, has been exhibiting significant and stable growth rates in excess of 20% annually, reaching an estimated annual industry turnover of approximately US$6bln at present. Forecasts suggest that the AM industry is likely to continue growing to between US$20–70bln by 2025. Compared to the size of some materials industries this is still small – the global stainless steel market alone is forecast to grow to US$127bln in 2024.

It is estimated that by 2013, AM materials were responsible for approximately 18% of the total AM industry turnover. Using the above estimate of current total industry size, this would suggest a current annual market volume of approximately US$1bln for AM materials. Coupled with the above forecasts on the AM industry, it is reasonable to expect that the market for AM materials will grow significantly, reaching between US$3.5–12.3bln in 2025. This means that making and supplying AM materials would be a very attractive proposition indeed. Stay tuned!

GE unveils BETA metal additive manufacturing system

GE Additive has unveiled the first BETA additive manufacturing machine for its A.T.L.A.S (Additive Technology Large Area System) project. The metre-class, laser powder-bed fusion machine has been developed to provide manufacturers of large parts and components with a scalable solution that can be configured and customised to specific industry applications.

The machine’s feature resolution and build rate has a scalable architecture that can increase the ‘Z’ axis to 1m and beyond.

Well-suited for large components with high resolution and complex geometries, such as aerospace-class parts, the machine incorporates the latest laser technology – and can also be reconfigured to incorporate additional lasers – and features discrete dosing to save on powder and cost. 

TRUMPF presents the TruPrint 5000

TRUMPF, Germany, a manufacturing solutions company, has presented its TruPrint 5000 at formnext trade fair in Frankfurt, Germany, late last year. The printer works according to the multi-laser principle and is equipped with three scanner-guided, 500W TRUMPF fibre lasers. 

These are fitted with optics specially designed by TRUMPF enabling them to operate simultaneously at any point in the system’s construction chamber. As a result, they can generate components much faster and more efficiently, irrespective of the number and geometry of the components.

The TRUMPF version is not limited to defined areas in the process chamber. This makes the 3D printer particularly fast and productive. Another reason for the speed is the exposure strategies developed by TRUMPF, which automatically calculate the ideal laser paths so that all three lasers can always expose multiple parts. The finished components are seamless, as the outer contours are produced with a single laser.