Laser sintering continues rapid development
By David Vink
Posted 14 February 2013
Investment in new selective laser sintering (SLS) products and materials was evident at the Euromold 2012 fair. EOS of Germany, a leader in SLS technology, has developed new materials, spurred on by growing demand.
At Euromold, EOS showed Primepart Plus PA 2221, a new polyamide12-based material with a defined lower refresh rate of 30% fresh powder. This reduces cost compared with 50% refresh rate for other PA12 powders. Technical properties are only “marginally below” those for the established PA 2200 grade, EOS says.
EOS has introduced the P110, the successor to the P100 compact class plastics SLS machine. Hannes Kuhn, managing director of EOS customer Kuhn-stoff, said the P110 was more flexible and precise, due to layer thicknesses between 60µm and 120µm, while the build envelope remains at 200mm x 250mm x 330mm.
Kuhn-stoff was involved in the EOS stand highlight: a live demonstration of a Wittmann robot using a laser sintered gripper frame. According to Kuhn-stoff, the plastic frame reduced several things: weight from 1,542g in the metal version to 215g; cost from €2,670 to €1,700; height from 87.5mm to 30.0mm; and production from approximately three weeks to four working days. Durability is around 5m cycles versus 10m in metal, but lower weight enables higher robot speed.
Wittmann Battenfeld introduced the gripper frame at its plant in Schwaig, Germany, and plans to introduce it in Vienna. Kuhn said it is also planning to produce four 19g “bronchial” flexible grippers, designed at Within Technologies (WithinLab) with finite element analysis (FEA) software.
He said that 19g sintered plastic grippers designed for 12kg loads could partially substitute 25g elastomer grippers for 40kg loads. The sintered plastic grippers deflect when pressed, and the fingers release when air is removed. The grippers had been tested to 750,000 cycles.
WithinLab announced in July that it has worked with EOS and others to develop a laser sintered PEEK craniofacial reconstruction skull prosthesis. The work was part of the EU-funded Custom IMD (implantable medical devices) 6th Framework project to enable implant deliveries to surgeons within 48 hours.
SLS powders are also available directly from Arkema. At Euromold 2012, the company presented Kepstan polyether ketone ketone (PEKK) and Orgasol Invent Smooth PA12 (48µm) and PA11 powders for SLS applications. Its renewably sourced (castor oil) 45-50µm particle size PA11 powder has higher ductility and impact strength than PA12 and is available as black and natural colour versions.
Exceltec of France exhibited 3450 Gbx glass bead filled PA11 material and renewably sourced Innov’PA PA11 1450 Etx cream and 1350 Etx black 50 µm grades. Its PA12 powders include natural white-to-yellow and colourable 1550 Xs (42µm) and grey 2550 GBAL (45µm), as a grade containing 30% glass beads and 5% aluminium.
Among the applications Exceltec displayed was a robotic handling gripper frame made by LMD Innovation for ABB in 1550 Xs. Design items on the company’s stand included some made in black and white PA12 grades by Cresalis, a French service provider, using Eosint and Sinterstation 2500 plus machines supplied by EOS and 3D Systems respectively.
Bart Van der Schueren, executive VP at Belgian additive technology systems software and service provider Materialise, presented the company’s Magics 17 software. Along with faster analysis, the new software release includes a new 3D Nester laser sinter module to save data preparation time, maximise powder usage, minimise production time and reduce SLS build failures by avoiding collisions and interlocking.
Van der Scheuren said the new software maximises the number of parts built in an SLS chamber while minimising powder use. This is important, due to high 30-50% powder refresh levels. He said increasing the compression ratio (component packing) in a build chamber from 7-8% to 12% means the new module could save as much as €70,000 per year in powder costs.
In an example, he suggested that by building a sphere with a hole, other parts could be sintered within the sphere and taken out through the hole. The Streamics software which Materialise introduced in April 2012 furthermore improves data communication between build data and machinery.
Van der Scheuren said he was proud Magics software was used to create a SLS model of the Brussels Atomium building which was displayed on the EOS stand. This was made by an Eosint P395 machine using a 9.3MB Magics file, with the “physical design only built during the slicing process”, he said. Materialise works closely with EOS in areas such as integrating software and machines with Materialise’s Build Processor and Streamics software.
Cipres Technology Systems of Germany presented 1mm deep “e-colouring” applicable to laser sintered opaque parts and sterolithographic (SLA) transparent parts. The e-colouring process includes “raw” for simple colouring, “standard” with treatment for improved surface appearance and “standard+” thermo-chemical treatment for improved thermal, light, humidity and soiling resistance.
Managing director Ingrid Prestien said there is strong demand for SLS parts with an intense deep black colour. Examples displayed included bottle openers and helmet covers, the latter designed by Snail in Buenos Aires, Argentina for Hockey Equipment, an Argentinian sports goods company.
Design bureau Purmundus organised jewellery design awards which it presented at the Design Night event at Euromold 2012. First prize among five winners, with a cheque for €2,000, went to Clement Zheng from Singapore for his quality of artistic design, as well as complexity and detail of production technology.
Zheng had submitted the Fusilli wrist band, laser sintered in PA. The design exhibited “surprising elasticity and a new materiality not possible through conventional product design methods” to give an item that “simply slips onto the wrist”, said Purmundus.
He also submitted the 200 x 200 x 40mm Sine bowl. Zheng said the bowl was conceived by abstracting physical oscillations and waves into simple trigonometric equators in space, which were used to create interwoven threads wrapping around 3D surfaces. Purmundus said the bowl has “unexpected visual lightness and a tactility that blurs the line between a hand-woven textile and the digitally fabricated”.
Most of the 16 Purmundus award candidates involved plastic materials processed by various forms of additive technology.
Laser-sintered Hockey Equipment helmets designed by Snail and coloured by the Cipres colouring process