FEATURE ADDITIVE MANUFACTURING Printing parts
Laser additive manufacturing is an excellent tool for prototyping, but now the technique is being used to build production-quality parts, as Tom Eddershaw discovers
W
hile the term 3D printing has certainly garnered a lot of attention in the media, industrial interest in additive
manufacturing (AM), as it is known in the manufacturing community, is partly due to its ability to work with new materials. Metal composites, ceramics, reinforced plastics, and many other powder-based materials can now be processed for parts in a range of industries. Visitors to the Laser Additive Manufacturing workshop in Houston, Texas on 12 and 13 March will get an idea of the range of AM technology available and the types of industrial parts being made. In terms of working with exotic materials, however, it is largely due to incorporating higher power lasers into the machines that allows production-quality parts to be built by AM. Andrew Payne, doctorial candidate at the Institute of Manufacturing, Cambridge, commented: ‘The process of building with metal has evolved at the rate that the lasers have evolved, in the sense that we can now produce lasers that are capable of fully melting a wide variety of metal powders. In their early days, fibre lasers weren’t powerful enough to process the higher melting point metals.’ Payne explained: ‘In the early attempts at metal powder bed building, the powder grains would be sintered rather than fully melted. Sintering is a semi-melting process whereby the grains adhere together but leave air gaps in- between. These “green” parts are then infiltrated with a liquid metal with a lower melting point that would fill the gaps, so you would have a fully dense part, but it wouldn’t be a single metal or even an alloy. You can still get functionality
16 ELECTRO OPTICS l MARCH 2014 Accurate and personalised products such as this mobile phone cover can be built using additive manufacturing
out of the part but it’s not the same as from a single metal.’
He continued: ‘Now, though, we have
sufficient power to fully melt the powder, and therefore it is possible to produce nearly fully dense parts. It depends on your strategy, but many methods give above 99 per cent now.’ The cost of the process is still very high, however – prohibitively so for mainstream industry. AM is only really feasible at the moment for expensive, smaller volume production markets, such as motor racing, high-end sports cars, and the aerospace industry.
The technique might still be only used for niche
The technique
might still be only used for niche applications, but the components made by AM are now functional
applications, but the components made by AM are now functional, which wasn’t always the case. Kevin Lambourne, managing director and founder of Graphite Additive Manufacturing, recalled that when first used, the process was named ‘rapid prototyping’. He explained that at the start: ‘Most of the parts were one-offs; they
weren’t functional and they weren’t accurate. But as other technologies were invented and materials started getting better, people began using them for production parts. A large part of the market still created prototypes, but functional manufacturing was beginning to come into play.’ Lambourne continued: ‘As they [AM companies] began to explore new markets and applications, such as in the aerospace and automotive industries, the perception of the technology changed and the phrase “additive manufacturing” was born.’ Whether it is called
rapid prototyping, additive manufacturing or 3D
printing, it still involves taking a computer-aided design (CAD) model, slicing it into thin sheets and then using a machine to manufacture each layer one on top of the other. While there are a number of different methods for AM, three of the most common approaches are: stereo lithography (SL, more commonly
@electrooptics |
www.electrooptics.com
Danny Tasmakis
Danny Tasmakis
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