Additive Manufacturing

JUL 2018

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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JULY 2018 Additive Manufacturing 18 TAKING SHAPE "The thermal process of debinding and sintering removes the polymer content from the component (the polymer decomposes and outgasses), ensuring a highly pure ceramic state that contains no additive residues. Following the debinding step, the component is sintered for up to two days at a temperature of up to 1,600°C." Traditionally, ceramic components are manufactured and processed using dry pressing, injection molding or grinding. The additive production of technical ceramic components offers several advantages over conventional methods, says Steinbach. "One big advantage is the elimination of tooling costs, which constitute a signifi- cant cost, especially for small to mid-sized quantities," he explains. "Using our LCM process allows us to even produce a single part at low costs, which wouldn't have been economically feasible to produce using conventional technologies. Additive manufac- turing allows for the production of prototypes which exhibit the final properties of the desired component, but it is also suitable for small and medium series production. Here at Steinbach, we mainly deal with series production." Aluminum oxide and zirconium oxide are currently available as ceramic materials in Steinbach's LCM process. For zirconium oxide, the maximum part dimension is 56 × 31 × 110 mm; for aluminum oxide, this is slightly larger with a maximum height of 117 mm. Due to the debinding process, in which the polymer is burnt out of the component, the wall thickness is currently limited to 4 mm maximum. Thicker wall thicknesses significantly increase the cracking probability of thermal treatment. Walls larger than 4 mm can be realized by design adjustments such as intrusions, penetra- tions or depressions, Steinbach explains. Steinbach is currently testing a new slurry made from aluminum oxide which will allow for increased wall thickness. According to Steinbach, the LCM process is more accurate than laser sintering, but produces smaller components. The accuracy of the process depends mainly on the shrinkage that occurs during the sintering process. "We are able to control the shrink- age process that occurs during production," Steinbach says. "The shrinkage that occurs amounts to ±1 percent of the length, but not more than ±0.1 mm. The surface quality is 0.4 micron Ra without postprocessing. The print resolution is 40 microns in the X and Y axes and 25 microns in the Z axis, which results in components that are indistin- guishable from conventionally manufactured parts." Steinbach is convinced that additive manufacturing processes for technical ceramics will continue to advance. "For example, ceramics are useful to produce high-wear spare parts. Machines commonly feature metal or plastic parts which are subjected to high amounts of friction and fluctuations in temperature, which leads to a shorter service life. "Ceramic components can help remedy this situation; however, many people are reluctant to invest in expensive tools and put up with the downtime this involves. Creating a special tool or mold often only makes sense when it involves quantities in excess of several tens of thousands of units. Additive manufacturing is a cost-efficient alternative to produce small batches or even single units. The low unit costs could open up completely new fields of application for ceramic parts." As a way of helping them to serve international customers faster, more cost- efficiently and with more customer-focused service, the company has recently pooled its expertise in ceramics with Protiq GmbH. Protiq, a member of the Phoenix Contact Group, has developed a web portal for uploading and configuring 3D models that can then be used to directly initiate orders and print jobs for additive manufacturing. The lithography-based ceramic manufac- turing (LCM) process starts with a slurry consisting of a ceramic powder and a UV- light sensitive momomer. After debinding and sintering, the end-use part is a gas- tight component with a smooth surface. The process is suitable for small to medium series production, as well as batch-size one. Images: Steinbach AG

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