Comprehensive powder characterization and supply chain optimization is vital if the metal 3D printing market is to bridge the gap between technology and certification, according to global testing company Element.

Element Materials Technology (Element) is an independent provider of materials and product qualification testing, inspection and certification services, covering the global aerospace, transportation and industrials, energy, and fire and building industries. Originally formed from the in-house materials testing and product testing laboratories of the Netherlands-based Stork Engineering Group, it now incorporates around 6,700 testing employees in 188 facilities in the Americas, Europe, Middle East, Africa, Asia and Australia.

It is in 54th position in the UK Sunday Times HSBC International Track 200, a list that ranks Britain's mid-market private companies with the fastest-growing international sales, measured over their latest two years, and has recently expanded its geographical reach by opening new aerospace laboratories in Greenville, South Carolina and acquiring businesses with laboratories and offices across the US, the UK, Germany, Japan, South Korea and Taiwan.

Complex materials

Element also established a US$7 million, 30,000 ft2 facility in Shanghai, China, specializing in chemical analysis, fatigue testing, failure investigation, mechanical testing, metallurgical analysis, on-site testing at client sites, a machine shop and heat treatment furnaces for the treatment of materials prior to testing.

In February 2020, Element invested in a lab dedicated to powder characterization for the additive design and manufacturing supply chain at its Huntington Beach, California, USA lab, which has been providing materials testing and consulting since 1982. (Figure 1.) According to the company, the Nadcap-accredited lab supplies a range of quality requirements such as routine high-volume testing and complex materials analysis and failure investigations.

‘In response to the growth in the 3D printing industry and increasing customer demand, Element has invested in a full suite of powder characterization testing to expand its current offering and provide customers with more technically demanding options,’ the company said in a press release. ‘Powder characterization is the front end of the 3D printing manufacturing process. It is required to ensure powder is authentic, pure, uniform and ready for processing and once printed, Element can also perform mechanical, dynamic, chemical and metallurgical testing on the materials that are produced.’

The lab can carry out testing including chemical composition analysis, powder sieve analysis, particle size distribution, flow rate, apparent density, tap density and gas pycnometry.

‘3D printing is well beyond an emerging market now and is an increasingly important space for us to be working and investing in,’ said Rick Sluiters, executive vice president, aerospace at Element. ‘Powder characterization has applications in multiple industries, including aerospace and medical devices, which are key sectors for Element.’

Aerospace design

In May 2020 it solidified its presence in the 3D printing industry by signing a multi-year contract with Morf3D Inc, a California-based aerospace additive design and manufacturing business, to provide testing at Element's lab in Huntington Beach.

Element says that its work for Morf3D includes a full range of materials testing, including powder characterization, chemistry, metallurgical, mechanical and fatigue testing. (Figure 2.) The Element team will also perform non-destructive testing at its lab in Rancho Dominguez, California with digital and traditional radiography.

‘Our extensive testing capacity, preferential pricing and delivery standards offer customers a fully integrated suite of services for technically advanced testing for the additive manufacturing (AM) industry,’ said Sluiters. ‘We are pleased to be working with Morf3D and other leading businesses in the sector and we'll continue to invest in this technology.’

In early June 2020, the company continued its focus on aviation by developing aerospace testing capabilities at its Montreal, Canada lab. Formerly known as Exova Pointe-Claire, the laboratory was traditionally used for transportation and industrials testing with a focus on rolling stock. However, since it is located near to other companies in the Quebec aerospace industry, it is now focused on aerospace testing, the company said.

Element Montreal’s capabilities includes materials characterization, such as tensile and compression, impact, hardness, as well as metallography (microstructure, grain size, and microscopy), atmospheric corrosion testing (salt spray), failure analysis, and weld evaluation.

I spoke exclusively to Chris Bohlmann, business development manager for AM at Element.

How important is powder testing in the 3D printing process?

Understanding the physical characteristics of the raw powder is key to producing manufactured parts with consistent properties. A full analysis and control of the powder metal feed stock is the first step for a consistent and repeatable part manufacturing process. The ability to recycle and reuse powder impacts the commercial viability for some products, which opens up variation in the feed stock that must be understood and managed.

Do you find that customers are aware enough of the importance of the right powder for their 3D printing process?

Most of the customers that have come to Element for powder characterization are very aware that powder properties greatly impact the process and ultimately the product being manufactured. Much of the work Element has performed has been for research and development processing and products. Metal 3D printing is a new process in many aerospace and automotive end markets. These customers are working to correlate the powder properties to the process yields of various AM equipment and ultimately to material integrity and the final part properties.

What aspects, such as size and flow, are most important to consider in 3D printing? What aspects tend to be overlooked?

 This is still an emerging technology, so much of the work is still in development including testing standards. Based on the volume of testing, conventional techniques such as size, density, flowability and chemistry are of most concern to our customer base. As the industry matures and the interactions of the powder, process and final part properties are better understood, alternate characterization methods may become more prominent.

 Do certain metal materials require more attention than others?

 Alloys that Element has been characterizing and testing have been commercially produced for a number of years in the medical, aerospace and automotive industries. For metallic powders, the battery of testing required is very similar across the material types – the size of particles and their morphology drives the testing challenge, not the chemistry. In fact, most powder material production processes now allow for certain material combinations to be made effectively for alloys that could not be produced with standard melting methods.

What industries require the most focus on powder testing and optimization?

 The manufacturing method is in use in a wide variety of industries from aerospace to medical, and optimization of the powder and process is important to all of them. Manufacturing development of powders and processes in the aerospace sector constitutes most of the activity Element has seen to date, while customer and industry specifications are continuously evolving to keep up with the appetite to move more products to serial production. We expect to continue to see a shift in products to moving from R&D and into production, which will shift testing activities toward product qualification, process control, and process optimization.

How do testing pre and post-printing compare?

Post-manufacturing testing is being used to verify process yield and product properties, and much of the post-printing testing is the application of standard specifications that have been the norm for metallic parts for many years, such as mechanical properties, density, and metallurgical analysis. These all verify that the process has produced parts that meet the part design requirements. In some cases however, companies require further post-process verification of product quality or characteristics that is not normally requested for products made with conventional methods. This includes verification of surface finish via specific methods or internal defect characterization and dimensions via methods like CT scanning or focused ultrasonic inspection. 

 How do you feel the 3D printing industry will develop over the next few years?

Aerospace OEMs and their suppliers are working to profit from the design and cost advantages of 3D printing, with partnership and collaboration two key themes. Currently, there is a significant amount of experimental data that has been generated and there are a number of machine and powder producers that have created material property databases (MMPDS) that describe the powders and parameters required to make products. These databases continue to evolve as more manufacturers seek to benefit from 3D printing – or fear being left behind in the marketplace. At the same time, OEMs and material producers and equipment makers continue to develop their own proprietary material allowables and design values so that suppliers can develop industrialized processes. 

 What issues/challenges do you think the technology will face over the next few years?

Currently, there is a gap between technical and process developments, and material and process standards, which the AM industry recognizes are a prerequisite to full industrialization. As a result, standards bodies such as ISO, ASTM and the SSAE have established working groups that have published standards and are actively working on new standards every year to keep pace with these developments. It’s clear that these standards being developed need to cover the entire product life cycle from product design to process, to part, to certification of product. Public/private partnerships such as America Makes are also creating projects that are advancing the understanding of design, process and application for 3D printing. However, adoption is never as fast as the first movers in 3D printing would like, so it’s important that adopters of this technology fully understand the process, its limitations, and what product it should be applied to. Developing process control standards and robust testing standards and techniques for both powder and part production will be key to universal acceptance of this manufacturing process.

Element Materials Technology;