Rapid payback from SLS machine

By now, most engineers are aware of rapid prototyping (or layer manufacturing) as a method of producing models of new products by the precise sequential addition of layers of material. Since the introduction of rapid prototyping back in the 1980s, the range of applications has evolved from design verification to the manufacture of tooling, metal castings and, more recently, rapid manufacturing (RM). RM is distinct from rapid prototyping (RP) in that RM involves the generation of production components either directly on an RP machine or as part of the process chain, not prototypes. At the same time, there is an increasing need for companies to reduce new product development lead times, which is forcing design engineers to look at alternative production techniques in order to bring new products to market ahead of the competition. A UK-based company, KV Automation based in Milton Keynes, has developed an 'advanced manufacturing technology' (AMT) based on selective laser sintering, that is cutting lead times and giving manufacturers the design flexibility they need to produce complex shapes quickly. The process also offers excellent surface finish and machineability. KV Automation is better known for designing and manufacturing pneumatic and fluid control products, including custom design solutions. Applications include sliding pneumatic modules for train doors, automatic milking systems and customised manifold assemblies for the pressing and coating of pharmaceutical tablets. Although KV receives most of its revenue from the sale of pneumatic and fluid control products, a new line of business has emerged recently which has saved the company more than £20k in manufacturing costs. In 2001, KV spent around £250,000 on a selective laser sintering machine, supplied by 3D Systems. Payback from the machine was achieved in under 12 months and the company is continuing to use the machine for both internal production parts and for customers. "We're currently producing products for customers using CAD data [Solidworks] taken directly into Magics mould tooling software and then the 3D Systems Sinterstation 2500 machine," explained Andrew Rea, senior engineer at KV. "A master model is produced using glass-filled nylon. This is then used to produce around 50 or 60 vacuum cast silicone moulds used directly in production. We can now produce more complex shapes, virtually any shape a customer requires using 3D CAD. For some clients, we've cut lead manufacturing lead times from months to three days because we've taken the whole concept-to-prototype process and taken it into manufacturing, to produce parts in hours. "We download stl files from Solidworks and the machine then slices the 3D model from bottom to top. Rather than using a print head, a laser is used to melt the powder or resin in those positions where the computer programme has told it that there is a solid layer. It gives very high accuracy and we can use steel, nylon or glass-filled nylon as the laser is powerful enough to fuse these materials. It means we can produce one-off injection mould tools or production parts in a couple of hours." Parts produced have a good surface finish ranging from 5 to 10 µm Ra and require little or no additional post processing, depending on the application. Highly complex geometries and features can be created that are normally difficult to produce using conventional technologies. KV simply converts the 3D CAD design into appropriate top and bottom mould tools allowing for appropriate draft angles and integrate complex, conformal cooling channels - which would normally take weeks to produce - in hours. Rea said the company had recently upgraded the Sinterstation 2500 machine from a one-axis laser to a two-axis laser machine. "This will enable us to produce complex parts with superior surface finish," explained Rea. "We're also looking at automatic powder feed systems for the machine, so that we can achieve improved machine productivity and we'll be able to leave the machine running for longer periods." KV has recently launched a new division for the semiconductor, medical and pharmaceutical industries, with one of the largest clean rooms (380 square metres) for pneumatic devices in the country. The Clean Pneumatronic Systems (CPS) division will offer its expertise in highly integrated electro-pneumatic control systems for very demanding clean room applications.