Rapid on the uptake

Although it's been a couple of decades since the first rapid prototyping systems came to market, many engineers remain convinced that this technology area offers little more than 'models' for sales and marketing pitches. The truth, however, is that today's mainstream rapid manufacturing techniques are capable of producing robust and functional parts made from the intended production material – or very near replica with equivalent properties. Processes such as selective laser sintering/melting (SLS/SLM), fused deposition modelling (FDM), electron beam melting (EDM) and 3D printing (3DP) are increasingly part of the process for progressive OEMs looking to cut swathes from the time it takes between product concept and first production run. Nowhere is this more acute than in the motorsport sector, as NASCAR specialist Joe Gibbs Racing can testify. JGR engineers typically have just three days to diagnose a problem, find a solution and implement it before the car ships to the next race. Image: This fast car required a fast response Stratasys' FDM additive fabrication technology, available in the UK from Laser Lines (01295 672500), makes it possible for engineers to perform this feat by creating concept models, functional prototypes, manufacturing tools and end-use parts in a matter of hours. BLOWOUT TRYS TO SPOIL THE DAY One Sunday, a tyre blowout on a JGR car caused it to crash, damaging the car and ending the team's race. It was later determined that a duct outlet supplying air to the tyre was not doing its job. In the past, it would have taken several weeks to get from solution to production part. However, using a Stratasys Fortus 3D production system, JGR mechanical engineer Scott Temple built a concept duct outlet from ABS-M30 plastic in just four hours. After completing a couple of iterations of the concept on Monday, Mr Temple was ready to move on to a functional prototype. He chose PC-ABS for good impact strength and used the Fortus machine to build the prototype overnight. On Tuesday morning, he performed bench testing and determined that airflow could be improved with minor changes to the design, again using the Fortus to create a new part late Tuesday morning. Tuesday afternoon, Mr Temple confirmed that the fourth design fitted perfectly and the airflow was now optimised over the tyre bead to keep it at the proper temperature. Using the Fortus, he then produced the part again – this time using high temperature PPSF plastic – to be used as tooling to create a fibre glass mould. On Wednesday the mould was used to create the final duct outlet part from carbon fibre. Like FDM, SLS/SLM produces thermoplastic parts, although metal components can also be created. In fact, laser sintering specialist EOS (01926 623107) recently unveiled a new machine for processing metal powders. EOS, which has sold around 270 metal systems globally, says EOSINT M280 includes significant technological developments, such as: a 400 W laser that can melt more metal powder per second; increased build height to 325 mm (from 215 mm); and optimised gas management to ensure stable melting behaviour. EOS has also introduced a new metal powder, EOS NickelAlloy IN625, a versatile material with high tensile strength, high processability and uniform corrosion resistance. Image: EOS NickelAlloy IN625 can be used for parts like this Of course, it's not just conventional engineering sectors that are benefiting from the evolution of rapid manufacturing techniques; industries such as jewellery and dental can also save considerable amounts of time and money by building fully dense metallic parts in stainless steel, cobalt-chrome and precious metals, using the newly introduced Mlab laser melting machine from Concept Laser – available in the UK from ES Technology (01327 701100). For applications within the jewellery sector, the freedom that the process gives to designers allows complex filigree structures to be produced, which would be difficult, if not impossible, using traditional methods. When applied to applications in the medical implant and dental technology sectors, the Mlab can produce components with micro or macro-cellular structures that mimic the structure of human bone and thus combine light weight with high mechanical load-bearing capacity. The medical implant and dental sector is potentially big business for rapid manufacturing processes, largely because each human is slightly different and requires bespoke solutions. Here, EBM scores highly, because it takes place in a high vacuum, so the parts are fully dense, void free and very strong. With this in mind, EBM specialist, Arcam (+46 31 710 3200) has recently announced FDA clearance of implants produced using its EBM technology. The US market for orthopaedic implants represents about half of the worldwide implant market. PLASTIC MOULD TOOLS So what of 3DP? Well, this process has evolved tremendously in recent years and today it is possible to build products fit for working trials in thermoplastic materials. However, certain innovative companies are thinking outside regular frameworks to develop even more markets for 3DP. A case in point is High Wycombe-based Ison Products, a company that specialises in subcontract product design and manufacturing, using its recently acquired Objet Eden 250 3DP system from OPS (01283 585955). "We recently had a customer who wanted to manufacture a rubber seal for a drinking vessel," explains managing director Paul Isaacs. "Originally, the client suggested using vacuum casting, but it proved difficult to replicate the exact material." Mr Isaacs had the idea of deploying the Eden 250 to 3D print a set of plastic injection mould tools – die and cavity. Once built, Ison was able to inject the tool with the exact rubber material intended for production of the seal. Because rubber has a low melting temperature, it didn't damage the mould tool. Image: Plastic injection moulds. Yes, using this set-up Image: And here they are Ison has since used this idea to produce security industry production parts that would normally have been manufactured by the investment casting (lost wax) process. Instead of making the tooling to produce the pattern waxes in metal, Mr Isaacs and his team simply 3D printed the injection mould dies, using the Eden 250, saving considerable amounts of time and money. That said, rapid manufacturing can still embrace conventional subtractive techniques. The firstcut service from Proto Labs (01952 607488), for example, uses CNC machining to produce functional prototypes from engineering-grade plastics or aluminium. The high degree of automation allows Proto Labs to deliver fast parts with surface finishes comparable to injection-moulded parts. Image: Rapid also means fast machining, too A recent beneficiary is Liverpool-based Butters Innovation, a manufacturer of scientific and medical instruments. Butters has recently been working on improving an existing medical device component. Because the firstcut service can deliver single aluminium prototypes, the company has been able to produce three working versions of the component for fitting and testing. In the process, Butters has been able to adapt the design, so it can be machined or moulded. This will make it easier and cheaper to scale up production, something that was an issue in the past, because of the large capital costs involved.