Renishaw is an engineering company with a wide product base – including medical devices, metrological instruments, position encoders, CAD/CAM systems and spectroscopy instruments. It’s the company’s additive manufacturing segment that is really attracting interest however – as the only manufacturer of laser-based powder bed machines in the UK, it’s riding the wave of popular interest in additive manufacture and 3D printing in general.
The company has made the most of this, collaborating with many diverse organisations to promote the technology. For instance, in October 2013, Renishaw collaborated with the WEAF (West of England Aerospace Forum) in Somerset, UK, to hold an additive manufacturing focus day, targeted at companies involved with aerospace design and manufacture. At the same time, it sponsored a free exhibition held at the Science Museum, London, exploring the future of 3D printing. The exhibition, ‘3D: printing the future’, held in the Antenna gallery, opened to the public on the 9th October and runs for eight months.
Earlier, in July, the company made the news manufacturing key prototype parts including the nose tip of the BLOODHOUND Supersonic Car, accelerating the design process considerably in the quest to break the 1,000 mph speed barrier.
“With 3D printing having such a high profile within media and political circles, it is fantastic that the only UK manufacturer of a metal-based additive manufacturing machine is able to contribute to this iconic British project. By helping the BLOODHOUND team a little along the way Renishaw aims to inspire a new generation of engineers both here in the UK and around the world,” said Simon Scott, director of Renishaw’s additive manufacturing products division.
With a global focus on developing AM markets, facing the challenge of acceptance in Germany has been addressed with the further strengthening of its applications expertise and service offering to customers through the acquisition of LBC Laser Bearbeitungs Center GmbH in May 2013. Renishaw now offers additional additive manufacturing services, including design and simulation, and the contract manufacture of metal prototypes and production parts, with a particular focus on conformal cooling for the mould and die industry.
A unique approach
Renishaw’s laser melting system is unique in the way that it that combines vacuum chamber preparation prior to re-pressurising the build chamber with Argon gas refill, to provide an oxygen free atmosphere as a key process foundation. The process then goes on to produce complex parts in a range of engineering materials including titanium and high temperature nickel alloys where the process uses a high power fibre laser, focussed to around 70 microns, to fuse atomised metallic powders together layer by layer to form the finished threedimensional part, a process that allows additional complexity to be ‘built in’ as the part grows in layer thicknesses between 20 and 100 microns, depending on the demands of the application.
MPR spoke to Simon Scott and Chris Sutcliffe, technical director for Renishaw’s additive manufacturing products division, about the process.
“There are other energy sources that can be used to melt powders but for our customers, who want finely detailed parts, from a flexible and robust shop floor machine the best solution that we have found is the combination of fibre lasers and a monocoque vacuum tight chamber,” says Sutcliffe.
“All the laser systems work on the same principles, but there are some important, if subtle differences. This is where we believe Renishaw offers a unique industry ready solution,” says Scott.
“In our case, when we are building the part, we use a vacuum to remove the atmospheric air in the chamber, and because this is done by vacuum we also remove the air from between the powder particles before will fill the chamber with inert argon gas. This means that the machines have a much lower oxygen content, leading to improved metallurgy,” says Sutcliffe.
“A by-product of the construction is additional stability, improving precision and significantly contributing to low running costs through the minimal consumption of Argon shielding gas.”
The gas consumption rate, after the initial chamber flood, is extremely low, around 10 to 15 L/Hr, and allows operation at oxygen concentrations below 100 parts per million – a vital factor when processing reactive materials such as titanium and aluminium. This contributes significantly to material integrity and mechanical performance.
The current systems have third generation designs. According to Scott and Sutcliffe, future optimisation is definitely on the cards. “Renishaw has an international reputation as a provider of world-class metrology equipment,” says Sutcliffe. “So it seems an obvious step to integrate this metrology knowledge into the equipment in some way.”
“There are lots of ways in which AM machines could be optimised,” says Scott. “We are looking at increasing throughput and enhancing precision through improved system control and process understanding. Scaling up is key; we are first and foremost a production company, not a prototyping specialist, and we want to get the technology out there into production.”
Future markets
Renishaw recently sold an AM250 laser melting machine to Swansea University, one of the UK’s top research universities. The system will be used by a new “Aerospace & Manufacturing” multidisciplinary research team within the university’s college of engineering. Part of the team’s focus is the ASTUTE (Advanced Sustainable Manufacturing Technologies) project, a Wales joint initiative part-funded by the EU’s Convergence European Regional Development Fund through the Welsh Government. The aim of the project is to promote growth within the manufacturing industry in West Wales by adopting more advanced technologies.
“Renishaw is very pleased to have won this tender against strong competition from other additive manufacturing suppliers,” says Scott. “There is great potential for additive technologies, and through the work of centres of excellence like Swansea University, the global possibilities to improve energy efficiency and product performance can be thoroughly investigated.”
Some commentators have suggested that, compared to other countries, the UK’s focus on AM is too ‘academic’ with not enough encouragement for the commercial side. But Sutcliffe and Scott disagree. “I wouldn’t say that’s true,” says Sutcliffe. “The technology is still at a very early stage. It’s not really been scaled up anywhere. Globally, the whole thing is just starting.”
Renishaw’s main markets are aerospace and high technology applications. “In the past, the majority of our machines were sold to academia and techology institutes. Recently, however, the commercial market has grown and we have sold machines to OEMs in the medical, aerospace and dental industries,” says Scott. “Automotive is a big potential market too – but at the moment we are just scratching the surface.”
In the past, a lack of a suitable supply chain has had repercussions in the development of AM. However, Renishaw says that with the additional investements now under way this is less of a problem than in the past. “There have been a few issues in the past, but currently it’s working okay,” affirms Scott. “Supply will obviously be a big issue in future, as the additive manufacturing market grows. The focus on traceable powders is important. It’s an exciting time for powder manufacturers.”
As well as proven materials such as aluminium, aluminium alloys and titanium alloy (Ti64), Renishaw and its partners are also researching very hard materials such as tungsten carbide and other carbides, which have double the melting point of titanium. “The focus for many companies and research establishments is on alloys that can achieve high hardness, toughness, strength, conductivity and temperature. Powder bed systems such as ours also allow the creation of new alloys by combining materials during the build process,” adds Scott.
The next step is to grow the industry. “To scale up, the cost of ownership needs to come down,” he adds. “But the cost of lasers is already decreasing and companies are buying multiple machines. It won’t happen immediately, but I can imagine a day when a business acquires a machine, plugs it in, and can straight away start production. Renishaw’s aim is to make AM machines ubiquitous in industry.”
