FEATURE: Cooksongold’s impressive new DMLS device

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BenchPro editor Sarah Louise Jordan travels to Birmingham’s Jewellery Quarter to see Cooksongold’s impressive new direct metal laser sintering technology in action and to find out whether years of testing and development has been worth the wait for the UK jewellery industry.

There’s a definite air of excitement when you walk into Cooksongold in Birmingham’s Jewellery Quarter.

Not only has the precious metal business been given a physical shake-up in the form of new extensions and a revised floor plan, but it has also reached the ready-for-sale point with its innovative and impressive direct metal laser sintering (DMLS) technology in partnership with EOS — one of the biggest producers of 3D printing technology in the world.

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This type of additive manufacturing technology isn’t widespread, but Cooksongold hopes to alter established opinions with its M 080 machine — a device that has been rigorously tested and refined to specifically suit the requirements of the jewellery and watch industries.

“The good thing about Cooksongold is that it has always been forward thinking,” explains European product manager David Fletcher. “We knew the scrap gold boom that happened five years ago wouldn’t last forever, so we looked at other businesses that we needed to get involved in and one of them was DMLS.”

Cooksongold’s journey into the world of DMLS started three years ago when its experience handling precious metals piqued the interest of EOS — a company skilled in plastics and non-precious metals for industry, with the aim of venturing into precious metals. “We needed a partner that was able to produce a decent machine for us, so we first of all took a large piece of equipment that was one of EOS’ standard, non-precious metal machines. However, we quickly realised it wasn’t going to be suitable for the jewellery industry,” explains Fletcher.

This isn’t to say the machine wasn’t exciting – it could produce parts and metal mesh designs that look very impressive – but the metal wastage was too high for Fletcher and the team at Cooksongold. Fletcher continues: “We immediately knew it wasn’t going to work and we said we need a specific, dedicated machine for the jewellery industry. We gave EOS a specific list of criteria explaining what the machine needed to do and they developed the M 080.”

THE PROCESS
Starting with a CAD file, EOS software splits a 3D design into hundreds of 2D layers in much the same was as other additive manufacturing technologies. Where the process differs, however, is with the application of a layer of gas atomised alloys or Advanced Metal Powders to a build platform. These powders, currently available in 18ct rose and yellow gold, flow like liquid inside their containers and are so fine they literally cling to available surfaces.

As a thin powdered layer is applied to the 80mm diameter build platform, a 100-watt laser solidifies the metal according to a 2D cross-section of the CAD file in use. This process is then repeated until the desired part is complete. In order to reduce waste and preserve as much of the alloy powder as possible, the powder cartridge and build platform are removed and any excess is carefully sieved and reused. Of course, the resulting piece is only semi-finished and polishing is required — something which isn’t necessarily easy when a complex piece is created in one go and has inaccessible interior surfaces.

In contrast to some of its competitors, Cooksongold’s M 080 has a raised build platform in comparison to a platform on the base of the machine, making it easier to access excess powder. Additionally, the process takes place within a glass chamber, containing any condensation that might occur as the laser makes contact with the powder. “All the time the machine is thinking about accountability,” Fletcher explains. “All of the other systems that are available have a reservoir of powder, which comes up and a snow plow-style arm pushes the powder across the build platform — so it is everywhere inside the machine. Here, we are delivering it via the cartridge onto the build platform in a far more accurate way, so there’s less wastage and loss.”

Cooksongold’s Advanced Metal Powders have required a similar dedication to experimentation and testing as the machine itself. Having been designed specifically for the laser parameters of the M 080, Cooksongold can guarantee its spherical powders (of less than 40 microns) will have the best possible result, in comparison to using other alloys that have never been used with its DMLS device and could require extensive R&D by an end-user.

Cooksongold European technical director Tony Staniorski ex plains: “If you talk to people in the jewellery industry, they may have started working on laser sintering for five, six, seven, eight years ago. There were some companies selling machines and you’d go out and buy your powder from somebody else, and I’ve heard from at least a half dozen people who’ve put a blanket over their machines basically because the powder wasn’t consistent. It doesn’t take much difference for a process that is based on this technology to go all haywire because you’re not supplying the same quality of material.” Once completed, pieces can be enamelled and soldered using any hallmarking quality 18ct gold solders and polished using standard equipment.

THE IMPORTANCE OF CAD
As with other technologies, DMLS relies on the skill of experienced CAD users who can create accurate 3D geometries for the machine to work with. In the case of the M 080, STL format files orientated in the direction a piece will be built in are an essential starting point, followed by the addition of support structures, before the data is sliced into 2D layers by the EOS Tools Software.

Of course, skilful CAD/CAM designers are essential, but those using DMLS (in comparison to other methods) can leave some, but not all, of their experiences at the door. It is an accepted fact that the best CAD designers have physical manufacturing skills developed at the bench, but that isn’t necessarily a condition for DMLS, which can operate outside of the realms of possibility.

There are certain practicalities CAD designers will need to follow when using the M 080, including swapping intersecting surfaces for watertight solid designs (Cooksongold literature recommends a Boolean function in most CAD packages), and supporting horizontal areas and edges below 30 degrees from the build platform, but this is relatively small in comparison to the creative freedom the technology can offer.

THE BENEFITS
“If a design has been designed to be cast, then you should cast it,” Fletcher explains when quizzed on the benefits of the M 080 and its potential in the UK jewellery trade.

Staniorski explains: “There’s a lot of misunderstanding from people that this will replace casting and this will replace conventional methods. This [DMLS] will reduce the need for some very labour intensive, hand-assembly conventional methods, but overall it is not ever going to be a replacement. It is another tool.”

Fletcher adds: “It is not going to replace goldsmiths and traditional goldsmithing techniques or casting. It is a new tool to enable jewellers and manufacturers to do things that they couldn’t before. Where this technology excels is freedom of design, especially with very complex structures which would be impossible to produce from casting.”

And DMLS does offer some incredible opportunities, especially for bespoke and one-off designs, while reducing the need for moulds. The M 080 can produce articulated pieces, including chainmail, spinning and hinged elements, plus thick-to-thin styles and hollow shapes in one run of the machine. Pieces can also be created with a thickness of 0.2-0.3mm depending on the design itself, which is very difficult to cast using more traditional methods.

Production times can also be efficient, depending upon the height of the geometry in the original CAD file, while requiring little to no attention from a technician. One case study currently used by Cooksongold to showcase the effectiveness of its device is a two-tone wedding band, comprising of an 18ct red gold inner seamlessly inserted within an 18ct yellow gold cage outer section. This multi-alloy ring was created without the need for tooling in four hours, plus a further two hours finishing time.
Support structures – required by the machine to build effectively – are created with weaker joins to ease separation and residue can then be removed with a handfile. When creating chain links, each link is attached to the platform but not its neighbouring chain link, ensuring the piece that comes out of the M 080 is fully articulated.

Staniorski adds: “If you walk out on to the high street and you look in the windows of jewellery shops everything is same because conventional methods only let you do certain things, so we can imagine that this tool will allow designers – once they understand what the technology is capable of – you can start to think outside the box and create things that you just can’t conveniently make any other way.”

RESTRICTIONS
Despite the almost endless possibilities, training experienced jewellers to think outside their comfort zones, and knowledge bases, to create something that wasn’t previously possible is a tricky endeavour. For Frank Cooper, a senior lecturer at the Birmingham School of Jewellery and technical manager at the Jewellery Industry Innovation Centre, training students to use DMLS technology will help to expand their minds before they develop an intuitive understanding of ‘what’s possible’ and ‘what’s not possible’.

Pieces produced in earlier stages of the machine’s development have a rough finish, something which has been improved in Cooksongold’s more recent tests. Fletcher explains: “It is slightly rougher than a casting, so pieces might require more polishing. We had two quite clear criteria when we started working with EOS and that was a good surface finish and no porosity – they were our key components.”

Pieces are likely to look rougher when created using DMLS because of the layerby- layer nature of the build itself. However, Fletcher and Staniorski say the technology is “getting closer” to producing pieces with an identical finish to a good quality cast.

Fletcher explains: “In the best locations, surfaces are close to those obtained by other methods. Depending on the design, there may be challenging locations where surfaces are rougher and more clean-up and polishing will be required.”

In recent months, Cooksongold carried out a polishing study with manufacturing jewellers from across Europe to test this very issue, with the majority confirming that quality parts – although slightly rough- straight from the process – can be finished to the same high standards.

OUTLOOK
Armed with its tried-and-tested device, Cooksongold plans to promote the machine and offer it to manufacturers across the world. It also offers a service package, including a bureau service, machine sales, powder production and sales, finance options, maintenance, repairs and training.

It is now developing its 18ct white gold Advanced Metal Powder, which can take anywhere between three and five months. Staniorski adds: “We build thousands and thousands of cubes and blocks [to test Advanced Metal Powders], starting at the fundamentals and working our way up to get the best combination of good porosity and nice surface finish. Maybe we can get higher density instead of 99.6, maybe we can get 99.8, but that might make the surface rougher — so we have to delicately balance things to get the best combination.”

With such a small number of atomisers in Europe – Cooksongold being the only company to have one specialising in precious metals in the UK – it is in a unique position to take DMLS and shape its trajectory in the UK market. They have exclusive sales rights for the M 080, which was first launched at the Hong Kong Gem and Jewelry Fair last year, and they plan to showcase a working machine at Baselworld .

With a price tag of 220,000 Euros, the M 080 is certainly an investment for manufacturers and brands (and potentially retailers) looking to add an extra facet to their offer. Units have been sold, both in the UK and in Europe, but it is perhaps too early to predict any kind of industry overhaul. However, Staniorski concludes: “Back in the late 1980s laser welding equipment came out and I remember being at trade events and everybody saying ‘wow that’s great, but what am I going to do with that?’ and now even the smallest workshop has a laser welder – it has become a mandatory piece of kit. I think laser sintering will go along those same lines.”

Perhaps the best advert for Cooksongold’s DMLS machine will be the pieces that are eventually lifted off the build platform and presented to paying customers. When such an eclectic and complex array of designs can be presented, it will undoubtedly act as a catalyst for experimentation and imagination.

This article originally appeared in the third volume of BenchPro in Professional Jeweller’s March 2015 issue. Read it online here.

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