January AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 9 1 5 PROCESS TECHNOLOGY Experimental apparatus for the hot embossing experiment. Courtesy of DGIST. LASER MACHINING BOOSTS SPACEFLIGHT A team of optical physicists at NASA’s Goddard Space Flight Center, Greenbelt, Md., is experimenting with a femtosecond laser that could rev- olutionize the way NASA technicians manufacture and assemble instru- ment components made of dissimi- lar materials. The team has already shown that this ultrafast laser can effec- tively weld glass to copper, glass to glass, and drill hair-sized pinholes in different materials. The team is now expanding its research into more exotic glass such as sapphire and Zerodur, and metals such as titanium, Invar, Kovar, and alu- minum—materials commonly used in spaceflight instruments. The goal is to weld larger pieces of these materials and demonstrate that the laser tech- nology is effective at adhering windows onto laser housings and optics to metal mounts, among other applications. Science and Technology (DGIST) Profes- sor Dongwon Yun developed a new pro- cess that can freely imprint fine circuit patterns on polymer substrate. Tradi- tional hot embossing process technol- ogy, which is used to imprint patterns of nm and µm size on a flexible polymer substrate, is used for mass imprinting of precise patterns at a low unit cost. However, it can only imprint circuit pat- terns that are engraved beforehand on the pattern stamp, and the entire stamp must be changed to apply differ- ent patterns. The team succeeded in develop- ing a new process that overcame the weaknesses of the conventional meth- od. First, they developed an electro- magnetic actuator that can apply tens of MPa pressure needed for the hot em- bossing process on the film. Then they fixed the actuator at the desired loca- tion on the film using heat and success- fully developed a precise location con- trol system that can imprint patterns, completing the new process technolo- gy. With this new method, hundreds of µm-sized fine circuit patterns can be imprinted on the desired location in the desired shape, reducing the addi- tional cost and time caused by pattern changes. www.en. dgist.ac.kr. Central to advanc- ing these applications is the laser itself. Due to its short pulses—measured at one quadrillionth of a second—an ultrafast la- ser interacts with ma- terials in a unique way. The laser energy does not melt the targeted mate- rial, but instead vaporiz- es it without heating the surrounding matter. As a result, technicians can precisely target the laser and bond dissimilar materials that oth- erwise could not be attached without epoxies. Another important application is in the area of micromachining. The ability to remove small volumes of ma- terial without damaging the surround- ing matter enables the machining of microscopic features, say researchers. These micromachining and welding ca- pabilities hold potential for numerous NASA projects. nasa.gov. HOT EMBOSSING PROCESS BREAKTHROUGH An international research team led by Daegu Gyeongbuk Institute of A Goddard team is using an ultrafast laser to bond dissimilar materials, with the goal of eliminating epoxies that outgas and contaminate sensitive spacecraft components. From left, silica welded to copper; silica welded to Invar; sapphire welded to Invar. Courtesy of NASA/W. Hrybyk. BRIEF Xometry, Gaithersburg, Md., is offering a new service where customers can request quotes for die casting, stamping, and extrusion work from its network of qualified partners. To receive a quote, customers upload part files to the com- pany’s site and specify part requirements. Then, an RFQ is sent to the partner network and shops can respond within seven days. It costs $20 to issue an RFQ and send it to the network. xometry.com .