Screen Printing - August/September 2016 - 38

FIGURE 4. Hp's Multi Jet Fusion 3D technology (left) uses both a fusing agent and detailing agent to achieve significant increases in print speeds. the initial target market is parts manufacturing (below), but in the future, the machine could be used to print electronic components. Images courtesy of HP be made from a variety of materials, with embedded conductive traces and the ability to encapsulate components such as sensors and LEDs. Its "main board" includes an embedded microcontroller that runs the functions of the other modules. Moving Toward Volume Production 3D printing is a great tool for prototyping, where the value of being able to change designs on the fly makes the process much more efficient despite the fact that printing a single product can take many hours. The long-term goal of suppliers, however, is to move toward higher volume production in order to expand into more lucrative markets. In order to do this, it will be necessary to vastly increase throughput. Printing thicker layers or moving the printheads faster, though, is not the answer, as the result will be low-quality parts that do not meet customer requirements. The answer for higher volume 3D printing lies in parallelization, which can be achieved through various approaches. Lewis' group at the 38 screenprinting University of Illinois, and later at Harvard, came up with a method to print from up to 64 printheads at once. The design needed to meet several challenging criteria, including the ability to withstand the high pressures required to print highly viscous fluids from a continuous filament; achieve uniform flow rates across the nozzle array; allow simultaneous patterning of more than one material; and be scalable for large area, rapid manufacturing. The design, which Voxel8 is in the process of commercializing, can print a 3D part that might currently take an entire day to print using a single nozzle in less than half an hour. HP has created a 3D printer expected to begin shipping in late 2016 that can print an array of parts simultaneously. The company claims that its Multi Jet Fusion proprietary architecture (Figure 4) can dispense 30 million drops of fluid per second. The process appears to be similar to SLS, but it uses both a fusing agent and a detailing agent, and is much faster. Initial applications are not geared toward printed electronics, but HP's vision includes the ability to tailor the properties of each voxel (unit cube, or 3D pixel) independently. If this were extended to control of conductivity and producing translucent voxels, it could be possible for the system to create printed lenses, sensors, or parts with embedded electronics. The promise of faster production at lower cost could be what it takes to launch applications beyond prototyping and truly disrupt the manufacturing process. Parallelization will need to happen at both the nozzle level and the system level, where multiple printheads dispensing from multiple nozzles are part of a network of several machines that create an efficient assembly line. When 3D printers can reliably co-print functional polymers and conductive inks fast enough to produce hundreds of parts per day rather than a handful, the industry may be ready to revolutionize electronics manufacturing. Julia Goldstein is a Seattle-based freelance writer specializing in technical, scientific, and business subjects. She holds a Ph.D. in materials science from the University of California, Berkeley.

Table of Contents for the Digital Edition of Screen Printing - August/September 2016