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LPW Team Outside HQ
LPW has taken on a member of staff a month for the last six months, and expect that to continue at at least this rate in the future
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Metals powder
Unlike others in the '3D printing' world, materials companies find it tough to get sexy shots of their output — but the right powder is fundamental to the right part.
This article is taken from the Jan/Feb 2014 print edition of TCT Magazine. To get in-depth stories first, along with exclusive print content, subscribe for free through tctmagazine.com/subscriptions
The recent increase in interest in metals-based AM as means of making end-use parts has once again focussed the industry towards ensuring the processes are production ready. As the core technologies stabilise and gain wider acceptance, machine makers can focus on the ancillary equipment and processes needed to see AM on the shop floor. In a vast majority of other production technologies machine makers make machines, and materials suppliers supply materials — companies like LPW are starting to make the same true for AM.
The last 24-36 months has, as well we know by now, seen an explosion in coverage of ‘3D printing’, a term used to describe everything from FDM and its clones through to selective laser melting. For industrial users, the ability to produce end use parts through additive means has long held a fascination, though has been regarded by many as an exciting future prospect rather than a real alternative to traditional means.
In part this has been because of the rapid development of the processes with major changes to the laser or electron beam systems, process chamber control, ancillaries and software — and part of this has been down to the structure of the AM ecosystem. A company looking at a new CNC machine is likely to buy the machine from company A, the controller from company B, the servicing from companies C and D, and materials from companies E, F, G and H. In the AM ecosystem, it has been expected that the entire needs of the client can be met by company A, the machine supplier.
Whether the machine manufacturer can actually fulfil all of these roles is a moot point, because single-supplier chains don’t work (or are not allowed to work) in the real world — especially once you start getting into production. It is natural therefore that users of AM machines will start to look for third party organisations to offer service contracts, control software and materials.
And here’s the rub; because metals AM is still so niche, the expertise required for service, maintenance and materials is largely siloed within the machine suppliers themselves, meaning that third parties are hard to come by.
In the materials sector, this manifests itself through non-AM focussed materials suppliers — that mostly already sell powdered metals for other industries —deciding to target the AM user community. If you want metal powder to process in your machine, there are tens of suppliers in whichever country you are based that will sell them to you. The problem is that these materials may or may not be validated for AM and are highly unlikely to be validated for the specific parameters you are running on your specific machine for that specific part.
For other processes that use metal powders (MIM, HIP) the size and shape distribution of the powder may be less of an issue than for AM, and it’s certainly true that not all powders are made equal. The properties required for accurate, reliable and repeatable processing in an AM system require bespoke production, sieving, measurement and handling — something that LPW are at the forefront of.
Rising to the challenge
The demand for a supplier of metals powders that understands not only powder metallurgy, but also AM in all guises has driven Cheshire, UK-based LPW to have developed a full range of AM-specific materials defined by how powders are required to behave for Selective Laser Melting (SLM), Laser Metal Deposition (LMD) and Electron Beam Melting (EBM). The powders are optimised in terms of chemistry and sizing specific to a machine type or application in conjunction with the end user. Core powders are supplied from stock, but rather than simply reselling, the stock powders are the first step in readying the material for use in AM.
TCT was able to visit LPW’s headquarters near Warrington — where the company has been based since February 2012 — to see first hand how the company achieves its aims.
Quality is ensured by strictly adhering to ISO 9001 and AS 9120 certified procedures. All powder is supplied with a certificate of conformance that contains test data for chemistry and sizing, with chemical data generated at an independent ISO 17025 certified laboratory. In addition to certificates of conformance, LPW has assembled a comprehensive range of equipment to size, blend, package, and characterise its powders in-house, offering enhanced testing reports. Internal characterisation includes rheology, hall flow, angle of repose, tap density, apparent density, scanning electron microscopy including EDX, entrapped porosity by scanning electron, optical microscopy, or helium pycnometry, laser size diffraction, sieve analysis, chemical analysis, and moisture determination by thermogravitational analysis.
Combined with the company’s knowledge of powders and AM processes, this technology can be applied to help the user understand their powder, resulting in more intelligent powder specification leading to a more stable production process.
Transport
Having the right powder, with the right morphology, flow characteristics and chemistry at the point of manufacture is half of the battle. The other half, especially with more reactive compounds, the transfer and packaging of the product to the point of use. Dr Phil Carroll, MD at LPW explained: “We carried out internal testing of all packaging by transporting containers to world-wide locations to test environmental extremes (temperature and humidity) and the effect on powders and packaging suitability. As a result as standard powders are packaged in HDPE containers chosen for robustness and resistance to moisture ingress with capability to package under Argon. We have identified potential for contamination from traditional silica gel packed in a waxed paper sachet and that this traditional product reaches capacity and stops absorbing moisture. LPW has developed a sachet made from a medical-grade plastic guaranteed not to contaminate powder, and prior to use are optimally stored in sealed boxes (guaranteeing that moisture will stay beneath 70% for 2 years from date of packing if container is stored in an environment of less that 90% RH and 40°C.”
AM is often touted as a ‘green’ alternative to traditional manufacturing, and while there are elements of truth to that the greatest savings tend to come from the efficiencies of the final part in use, rather than the process of producing. Once lasers and their ancillary systems, the energy required to create the powder and post-processing are taken into account, the act of making a part via AM can be very energy intensive.
Phil explained how LPW believes in developing favourable waste management solutions that will help users minimise their environmental footprint whilst maximising the value of their scrap raw material: “Through use, recovery and recycle LPW provides a complete life-cycle management for powders. The PowderSolve online software has been developed to provide an unparalleled level of multi-powder information for tracking the life-cycle of AM powder for example. With full traceability of the powder, from production through repeated use, including after blending, PowderSolve offers the most comprehensive database for powder and trend analysis data, which helps to maximise powder value. It enables material users to analyse physical properties, technical characteristics and chemical composition through a user-defined reporting tool.”
Given the rate of change within the company (they’ve taken on a member of staff a month for the last six months, and expect that to continue at at least this rate in the future) I asked Ben Ferrar, General Manager, what the future held: “We will be implementing ISO 13485 quality management system specifically for the design and manufacture of medical devices and for the aerospace industry we are working towards the AS9100 quality management standard, with an audit scheduled for Q2 2014. More generally the goal for the end of 2014 is to become an ISO 17025 test lab tailored specifically for the needs of AM production users, which will make us the first of a kind. In addition the company has major expansion plans and will be launching LPW USA in Q2 2014, including a new distribution facility for the North American market.”
