Malvern Panalytical is a developer and supplier of instruments that are designed to help users gain a better understanding of materials. Its technologies are said to be capable of measuring a host of material parameters, from particle size, shape and concentration to molecular weight, size and structure. With these insights, Malvern believes its customers will be able to better estimate the behaviour of products and optimise their performance.
The company’s analytical instrumentation products are used in a range of vertical markets and Malvern is also active in the additive manufacturing space, offering characterisation solutions for polymer and metal materials used in the powder bed fusion, stereolithography, fused deposition modelling and binder jetting processes.
To learn more, TCT spoke to John Duffy [JD], a Segment Manager at Malvern Panalytical with a focus on additive manufacturing and specialty materials. In this role, he works closely with industry and academic partners to better understand their characterisation requirements now and in the future.
Why is the additive manufacturing market important to Malvern Panalytical? And what does the company feel it is bringing to this market?
JD: Our journey in this market started in 2014 when the industry started showing an interest in our laser diffraction and imaging solutions for particle size and shape analysis. We then merged with our sister company PANalytical, which specialises in X-ray analytical equipment, to form Malvern Panalytical.
It didn’t take long to realise our particle characterisation and X-ray solutions both had an important part to play in this market, the latter for elemental analysis (X-ray fluorescence; XRF) and microstructural analysis (X-ray diffraction; XRD). The excellent solution fit, combined with impressive growth projections for the market, encouraged us to expand our efforts.
Why is material characterisation an important consideration for users of additive manufacturing technologies? And which characteristics are important?
JD: The bulk properties of an additively manufactured component depend on the underlying microstructure. This, in turn, depends on the properties of the raw materials used as well as the process conditions. The materials are the biggest source of variability for a fixed process, and inconsistent material properties will lead to inconsistent properties in the finished component.
This is even more critical for powder bed processes as there are even more material variables to consider, such as particle size, particle shape, porosity, chemistry, thermal properties, and the presence of impurities. Strict quality control protocols are essential, particularly for aerospace and medical applications, to ensure the powder supply is consistent and meets specifications. It’s also wise to regularly check recycled powders because repeated exposure to the AM process can have harmful effects on the powder and the build.
However, material characterisation is important for more than quality control. It also plays a vital role in research and development, whether investigating novel alloys or composites or developing a new AM process.
Can you explain how you help manufacturers to understand material characteristics and what they must look out for when assessing the quality of raw materials?
JD: Firstly, we provide the scientific instruments needed to measure the relevant material characteristics – whether that’s particle size, molecular weight, elemental composition, or phase analysis. But acquiring data is only part of the story. We also work closely with customers to optimise the test protocols for their materials and help them understand and interpret their data – this is usually the toughest aspect.
What are some of the key considerations for metal 3D printing users? Which characteristics must be monitored and how can they affect the printed component?
JD: Most of our customers in the metal additive manufacturing space are using, or providing materials for use in, powder bed processes such as SLM, EBM, and Binder Jetting. The powder characteristics our customers are usually most interested in are particle size, particle shape, and chemistry.
Particle size and shape are important because they affect powder packing and flowability. Powders that pack consistently well to give a high-density lead to higher-quality components with fewer flaws, while the ability to spread the powder evenly and form a uniform layer with no air voids is also critical. This generally calls for a spherical powder with a well-defined particle size distribution.
Chemistry is also essential because a powder needs to comply with the specified material’s alloy composition. There is no value in having a metal powder with the correct particle size and shape if the chemistry is wrong, as the end-component will not have the properties you require. By chemistry, we mean the key alloying elements and the interstitial elements such as hydrogen, carbon, oxygen, and nitrogen. Contaminants can also be problematic, especially when the contaminant has a higher melting point than the build powder. One example of this is tungsten contaminants in titanium powder.
Ultimately, the goal is to produce metal components with the right physical and chemical properties. Powder and process optimisation is a way to achieve that, but how do you know that goal has been met? Our XRD systems are very popular for this since they allow the microstructural characteristics of a component to be probed. You can check characteristics that can directly impact end-use performance, such as phase composition, grain size, texture, and residual stress.
What are some of the key considerations for polymer 3D printing users? Which characteristics must be monitored and how can they affect the printed component?
JD: Several AM processes use polymeric materials, and the polymer’s physical and chemical properties need to be tailored to that process. [With] Selective Laser Sintering (SLS), for example, (as with metal powders) the particle size and shape distribution must be optimised for packing and powder flow.
These are classed as extrinsic properties, but the polymer also has important intrinsic properties such as thermal, optical, and rheological properties. These intrinsic properties are related to the macromolecular structure of the polymer(s), including the degree of crystallinity, which can result in complex thermal and viscoelastic behaviour.
The presence of additives and fillers will also have an influence. This makes rheological testing an important technique for understanding the temperature-dependent flow characteristics of polymers along with thermal analysis techniques such as Differential Scanning Calorimetry (DSC). Ideally, you require a wide enough sintering window and low enough viscosity to facilitate fusion and relaxation. But you also need a cooling and crystallisation regime that gives dimensional stability once fusion is achieved.
Malvern Panalytical has the tools for characterising the structural characteristics of polymeric materials responsible for this behaviour. Gel Permeation Chromatography (GPC), for example, is often used to determine the molecular weight distribution of macromolecules, and when combined with additional detectors can also reveal information about the molecular structure. Similarly, XRD provides insight into the semi-crystalline nature of these macromolecules.
There’s a limited portfolio of materials suitable for additive manufacturing right now, particularly on the polymer side, but that’s being addressed.
Can you explain which Malvern Panalytical products are suitable for the analysis of metal/ polymer materials and what their respective capabilities are?
JD: For particle characterisation, the main instruments we sell are the Mastersizer 3000 and Morphologi 4, which are bench-top instruments that can be used with polymer, metal, and ceramic powders. The Mastersizer 3000 uses laser diffraction and only takes a couple of minutes to provide a complete high-resolution particle size distribution. We also have an online laser diffraction system called Insitec, which can be integrated into a process to provide real-time particle size information.
The Morphologi 4 is an automated imaging system used to classify and quantify the size and shape of particles. It does this by combining particle size measurements, such as length and width, with assessments of particle shape features such as circularity and convexity. It’s ideal for quantifying the sphericity of particles or identifying irregular particles in a mixture and complements laser diffraction very well.
To determine the elemental composition of metal alloys and ceramics, people often use XRF systems such as our Zetium and Epsilon. XRF also saves a lot of time and money compared with alternative techniques and can detect contaminants or inclusions in a part or powder. For microstructural analysis, bench-top XRD systems such as Aeris are popular for conducting phase analysis of metals. Multi-purpose diffractometers such as Empyrean can be used to find out more about texture, grain size, and residual stress under a range of conditions. Often XRD is used to study the structure and crystallinity of polymers and ceramics.
Finally, if you need to determine the molecular properties of polymer resins or powders, GPC systems such as OMNISEC are ideal. OMNISEC combines chromatography with several detectors to provide detailed information on absolute molecular weight and molecular structure, such as branching, even for low-molecular-weight species.
To determine the elemental composition of metal alloys and ceramics, X-ray fluorescence (XRF) systems such as our Zetium and Epsilon are routinely used. XRF also offers significant time and cost savings compared with alternative techniques and can also be used to detect contaminants or inclusions in a part or powder. For microstructural analysis, bench-top X-ray diffraction (XRD) systems such as Aeris are routinely used to conduct phase analysis of metals. And for additional information on texture, grain size, and residual stress under a wide range of conditions, multi-purpose diffractometers like Empyrean can be employed. XRD is also widely used to study the structure and crystallinity of polymers and ceramics.
Finally, for determining the molecular properties of polymer resins or powders, Gel Permeation Chromatography (GPC) systems such as OMNISEC are ideal. OMNISEC combines chromatography with several detectors to give detailed information on absolute molecular weight and molecular structure, such as branching, even for low molecular weight species.
Which industries use your technology to analyse additive manufacturing materials?
Our technology is used across the entire additive manufacturing landscape, from academic research to final part manufacture. From metals and polymers, to composites, ceramics, and foods and medicines. My focus is on polymers, ceramics, metals, and composites, and I engage with universities, technology centres, material suppliers, machine manufacturers, and end-users in aerospace, automotive, and medical.
Finally, what does the future hold for Malvern’s activity in the area of additive manufacturing?
Additive manufacturing is, and will continue to be, a focus area for Malvern Panalytical, similar to advanced manufacturing in general. A greater emphasis on the raw materials will make characterisation even more critical, not just for quality control but also in developing new materials and processes. There’s a limited portfolio of materials suitable for additive manufacturing right now, particularly on the polymer side, but that’s being addressed. There’s also lots of great work in the field of composite materials and metal alloys to help address the future need for strong, lightweight components in automotive and aerospace applications.
But the opportunities go beyond automotive and aerospace. Malvern Panalytical is engaged in many different industries and applications, including semiconductors, batteries, pharmaceuticals, and construction materials. 3D printed buildings and small batches of medicine with tailored dosages being inkjet printed are already becoming a reality – so the future looks bright.
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