Tuesday, 25 August 2015

Stratasys PolyJet Multi-Material 3D Printing

For the few products made of one material and color, prototyping and production can be a one-step process. However, most products are assemblies, comprised of several parts that are typically made from different materials, in more than one color (Figure 1). Each part must be individually machined, molded or cast in the desired material and color and then assembled together. Painting and decorative operations may also be necessary to complete the product.

Figure 1: 
3D printed calculator with a rigid housing, clear display and soft- touch keys with printed characters.

Multi-material 3D printing creates prototypes that simulate final- production parts in a single operation, which improves functional evaluations and overall appearance. Using PolyJet™ Connex™ technology, a single part can have a variety of mechanical properties, colors and levels of opacity and durometer. This unique technology is fast and efficient when creating prototypes with features that exemplify the finished product (Figure 2). PolyJet technology is a 3D printing process (additive manufacturing) that builds objects layer by layer, from computer aided design (CAD) files, by jetting tiny droplets of liquid photopolymers. With PolyJet ’s Connex family of 3D printers, two or three materials are jetted simultaneously and often blended to create digital materials.

Figure 2: 
3D printed glasses with clear lenses and a multi-colored frame.

The blended digital materials combine to deliver a wide range of material characteristics. Some blends mimic ABS plastic, while others simulate rubbers with different Shore A values. Digital materials also combine transparent and colored materials to alter appearances. For example, Connex 3D Printers offer more than 1,000 color options from an inventory of just 22 base materials (Figure 3). This provides designers and engineers with a single- operation prototyping option for parts that would otherwise require multiple fabrication steps.

Figure 3: 
Connex 3D Printers offers 20 color palettes for rigid and flexible materials.

Multi-material 3D printing reduces the time, effort and expense in the production and evaluation of products that combine multiple properties such as rigid, rubber-like, overmolded, and colored features (Figure 4). It also increases utilization and cost- effectiveness of the 3D printer by reducing downtime for material changeovers and increases the variety of material characteristics in parts produced in a single build (Figure 5).

Figure 4: Overmolded, multi-colored razor handles.   
 Figure 5: Multi-material printing

Engineers and designers at Trek Bicycle in Waterloo, Wisconsin, are obsessed with continually improving their products. Trek’s prototyping lab was among the first to adopt the Objet ® 500 Connex3™ 3D Printer, an advanced, color, multi-material 3D printer using PolyJet technology. It creates prototypes that look and feel like production parts, with more material options and more uptime than ever before.

Engineers at Trek embraced multi-materials to integrate soft, rubber-like components into models built with durable Digital ABS™, one of the digital materials available with Connex3 3D Printers. This is important because many bicycle parts contain both soft and rigid materials. Prior to using Connex3 technology, engineers had to build these parts in separate jobs, swapping out 3D printing materials in between, and then bond the components together. The alternative was to make parts in one print job, but with less-than-optimal material characteristics.

“It ’s important for our prototype parts to look and feel like production parts,” says Mike Zeigle, manager of Trek’s prototype development group. Accessories like handlebar grips and chain guards require the same realism for fit and function testing (Figure 6). Multi-material 3D printing gives Trek’s designers the ability to quickly develop prototype parts with all of the desired characteristics of final-production parts.

Figure 6: Durable Digital ABS chain guard with rubber-like components made in one print job.

Trek’s engineers also use multi-material 3D printing to communicate through color. The product development team was able to translate finite-element analysis data into a physical 3D color map of a bike seat showing the pressure a rider puts on specific areas of the seat (Figure 7). This lets designers actually “see” these pressure points, allowing them to decide where to put high-density foam for a better-performing seat.

Figure 7: Color map model shows the pressure that a rider puts on the seat.

The ability to 3D print parts with different material properties in multiple colors gives Trek Bicycle faster prototyping capabilities as well as more descriptive concept communications.

Source: Stratasys Application Brief