Modern mould making

8 mins read

The combination of the word 'growth' with 'mould tool making' might seem counter-intuitive, as far as the UK goes. But one organisation is employing latest design and manufacturing techniques to demonstrate otherwise, as Andrew Allcock has discovered (extended version of print article)

High Wycombe-based CRDM offers a unique combination of rapid prototyping, rapid manufacturing (EOS laser sintering technology), mould tool design, project management and manufacture, plus injection moulding. Celebrating its 15th anniversary, the 42-employee company has seen its business grow more than 63 per cent over the past five years, reaching a turnover of £3.5 million, and it sees yet more growth, particularly related to its mould tool making activities, with rapid manufactured mould tool inserts featuring conformal cooling the company's next major push. Image: The insert here has been produced via rapid manufacturing - laser sintering Currently, the business is split, with one third of its sales coming from its rapid prototyping (RP) activities and two-thirds from its mould tool making (rapid manufactured/machined inserts; bolsters are typically bought in), moulding and rapid manufacturing of metal components. About one third is export, with this centred on the rapid manufacture of metal parts and tooling. But, intriguingly, rather than the two 'modern' processes – rapid manufacture of plastic parts (RP) and rapid manufacturing of metal parts (RM) – it is the 'traditional' area of mould making that holds out most promise for growth in the near term, although the term traditional is, perhaps, a little misleading, since the company employs rapid manufactured mould tool inserts. As director Graham Bennett explains, the RP market has seen many low-cost machines enter the market, with computer giant HP also entering the 3D printing fray recently. This has made in-house RP much more viable, with a corresponding negative impact on externally supplied RP services, with the exception of high performance engineering materials. "The market has gone much the way that we expected it would. It is clearly a big market, if companies such as HP are interested, and I expect other large companies to follow," he offers, adding that: "growth for us, therefore, will come from mould tools and RM metal components, while continuing to offer high performance engineering materials in RP." He continues: "The sort of thing we are interested in is progressing the use of RM metal parts for low volume production activities. This currently includes medical parts, also compelx manifolds for high pressure liquids, where users require relatively few parts – up to a few 1,000/year – using metal sintering, mainly because the geometry would be difficult to produce using traditional technology. Image: Rapid prototyping has come under attack from low-cost technology, but high performance engineering materials remain viable for specialist bureaux MATERIAL PROGRESS "The big boom for us has been engineering standard materials, such as stainless steels, hardenable tool steel (55 Rc) and cobalt chrome, which has enabled us to get into markets where the original bronze material was not acceptable." CRDM employs EOS laser metal sintering technology, with its most recent investment an EOS M270 unit, capable of processing these latest materials (250 by 250 by 200 mm envelope). Typical part size for RM applications is said to be around that of a golf ball. So, the production of rapid manufactured production parts is already reality, but the next hurdle is demonstrating the delivery of parts to the same quality, time after time, through an agreed acceptance process or set of processes. "We need to prove to the goods inwards QA guy, in a variety of industries, that the parts that those companies are receiving are always up to spec. And the problem is, there is no standard approach, as there is for machined parts. There is no industry standard for a layer manufactured component." In fact, through a separate activity, ALMC, CRDM is delivering consultancy to companies to help them establish such processes. Aerospace and medical companies have been among the tally, Mr Bennett offers, and these processes are independent of the supply source, so parts from any supplier, or internally, can be subject to them. A useful adjunct to CRDM's slower-than-hoped growth in RM metal parts production, ALM has, in fact, turned into parts production for CRDM. "This issue of repeatable quality is a challenge for the whole layer manufacturing industry, but it is also the opportunity for a very big market. If we can get this right, it will revolutionise industry. "We have two possible routes to go forward. The test coupon method, where we produce these, giving a CAD drawing to the customer, indicating where they were in the build envelope – some in X, some in Y and some in Z – and, if all these pass, the batch can progress. Some companies want to destroy every second component, very expensive, but it's all about building up confidence, such that the number of parts tested can be reduced and we can ultimately rely on test coupons. "Some companies are willing to go this route, others not. But the perfect result would be if the machine manufacturers made models that provided relevant feedback to allow control and repeatability. In fact, one or two manufacturers are moving in this direction, but there isn't, as yet, the perfect machine that monitors everything it does as it builds. So, for example, we would like to have a complete analysis of what is going on at the laser focus during the build process: temperature, material composition and speed of movement, with this output independent of the parameters driving the machine, and with this feedback, hopefully, going back to the machine." Concept Laser has brought out a device which, it is said, offers such a solution (see box item, below), but Mr Bennett says he has yet to see it demonstrated. "If such machines were available, that would be a big step forward, because you could provide a log with the produced parts." In fact, large companies such as Boeing, Airbus and BAE Systems have requested such developments from machine makers, the CRDM director highlights, but the machine developers, quite naturally, want to know what the market will be, and this is not firm. The other issue with RM parts, that of surface finish, is being tackled by follow-on process machine developments, Mr Bennett adds, highlighting a highly polished knee joint as an example. So rapid manufacturing as a production process still has some way to go. Indeed, CRDM admits that its hopes for growth in this area have not been realised. Image: Laser sintering - not much to look at In contrast, the traditional activity of mould making has, and will, see faster growth. It is an activity that CRDM started in earnest some five years ago, at the suggestion of Mr Bennett, in fact, but with the full backing of the management. It has proved to be pivotal in the organisation's growth – and even its survival, with it growing year on year through the recent recession. With the introduction of maraging steel powders, the company has not only been able to deliver longer lasting plastics injection mould tool inserts – "well into the area of production tooling" – but also aluminium die-casting tools. An aggressive process, one die-set has produced 10,000 parts. "Intended to be a prototype tool, it is still going strong," underlines Mr Bennett. But now the target area is mould tool inserts having conformal cooling channels, which will support faster cycle injection mould tools. This technology is currently undergoing tests in-house. Not a new technology, having been the subject of EU research initiatives, the CRDM director offers it was one that "tried to run before it could walk", as the technology at that time was bronze sintered inserts – which would not last – not the hardened ones now available via the newer materials and which can produce "millions of parts". MERGING OF TECHNOLOGIES "The two technologies [RM and conformal cooling] have now come together. There has been the thinking that, if you want a low-cost tool for high volumes, you go to China; which is true. But, if you want a low-cost tool for volumes that will produce many parts at high speed, you can't get that in China. And while the tool won't be at a 'China price', the cost of the whole package – tool and moulding, where you can reduce moulding cycle times by anywhere from 20 to 50 per cent means that the whole package is significantly cheaper. That's the place we have identified as where we want to go in the near future. We have started two or three projects in that area to demonstrate to key clients that we can deliver." Indeed, one interested company is based in South Africa. But, for CRDM to get itself into a position to be able to offer conformal cooled mould tooling, the organisation had to establish itself in the traditional area, explains CRDM chairman Martin James. "Conformal cooling has been a long- term goal. As a pure rapid prototyping company producing principally plastic parts, to deal with customers looking at conformal cooling, unless they perceive you as a mould tool manufacturer – somebody that understand tooling – you won't get traction." The company has built almost 500 metal sintered tools since it started in 2000, placing it in the "top 10 companies in the world" in this area, it is claimed – including machined inserts, the total is 800-900 mould tools. Interestingly, CRDM has developed its mould tooling business because of the reticence of mould tool makers and moulders to take on board its sintered insert and conformal cooling technology. It had originally thought that it would be a supplier to such customers. "That probably isn't going to happen. Nobody is getting traction with the toolmakers to go this route, similarly for moulders," Mr James explains. "Their perception is that we are taking something away from their business. Our view is that 'you are already losing your business, but here is some technology that you can fit into your tools and retain mould making/moulding capacity in the UK and do what you do best.'" The people who really want it are the end users, says CRDM, with Mr James adding that the organisation is rather "shocked" at the lack of engagement with mould tool makers and moulders, hence its move into mould tool design and manufacture. Concludes CRDM's chairman: "Three years ago, we were more of an RP company; today, we are more of a tooling company. In the last 12 months, we have really upped the game on our tooling personnel, adding project management teams and QA people. Image: CRDM has its own in-house machining capability, a well as rapid prototyping, rapid manufacturing and moulding "We have migrated to an additive layer manufacturing toolmaker, which is a much more comfortable place to be, because we are differentiating ourselves and adding another dimension to our business, reducing our reliance on RP. Having said that, moving into big tooling projects is actually boosting demand for RP and silicon mould tooling, to support short term production of plastic parts ahead of tooling availability." Box item Real-time monitoring At the end of 2009, Concept Laser GmbH (ES Technology) introduced its QM system to monitor what it calls its LaserCusing process (made up of the letter C from Concept Laser and word Fusing (complete melting). The QM system monitors the construction process in real time, looking at all the process components: melt pool; documentation; process gas; powder; and temperature. A key element is the real-time monitoring of the melt pool, which requires a very high sampling rate at high resolution. LaserCusing is a microwelding process in a confined space — a track width of approximately 100 µm with a layer height of about 20 to 50 µm. This melt pool module views the construction process at several thousand images per second, analysing the relevant melt-track data, which is recorded and evaluated by software. Another key element is the powder module. Sieving of the metal takes place in parallel with the construction process, using a fine mesh that can be less than 50 µm. This powder module can be made inert by means of a protective gaseous atmosphere, typically argon. The company has constant monitoring and regulation of the oxygen concentration in the process gas, with another development the monitoring of volumetric flow rate. A temperature module monitors temperature-sensitive machine components and provides information about their current state. A documentation module analyses the ongoing construction process and makes it possible to provide reports on all of the data held within the real-time QM modules. The ultimate objective, says the company, is a self-regulating process. First published in Machinery, December 2010