Additive Manufacturing

NOV 2017

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.

Issue link: https://am.epubxp.com/i/894355

Contents of this Issue

Navigation

Page 62 of 67

AM / From Master Patterns to Mass Production additivemanufacturing.media 61 this printer that helped the Weber brothers launch their sili- cone tooling business into the world of additive back in 1995. Creating silicone tooling involves first creating a master pattern; at Forecast 3D, the master is commonly 3D printed us- ing SLA or FDM technology. Then, a finish is applied to make this pattern an exact replica of the desired molded outcome. Forecast 3D suspends the master inside a custom-built box and fills it with liquid silicone. The box goes into an oven to cure, then is separated into two by cutting around the pattern. The master is removed, and the remaining silicone tool is ready to be injected with resin in a vacuum oven to make production parts. The advantages to this process include the ability to make use of 3D printing's speed while achieving the high sur- face finish of injection molding on the final production parts. While effective, the silicone casting approach didn't make sense for all Forecast 3D's work. For customers needing more than hundreds of parts, the investment in a pattern and mul- tiple silicone tools could be cost-prohibitive. In the past, the logical next step for thousands of parts was typically injection molding. When the Weber brothers were introduced to Multi Jet Fusion (MJF) 3D printing, what they saw was a new logical next step. In addition to being a faster, more cost-effective option for short runs, 3D printing also has fewer design restrictions than injection molding, in the company's experience. "There are many rules that must be followed in order for a design to be successful in the injection molding process," says Corey Weber. "You have to consider draft, parting lines, undercuts, wall thickness and direction of pull. With AM you don't have those rules that need to be followed. This makes designing parts so much simpler and faster." An example might be a mounting boss perpendicular to the direction of pull in a cavity. "That would be impossible with injection molding," he says, but "With AM, no problem!" The company has also added metal sintering machines from EOS and SLM Solutions, plus CNC machining equip- ment over the years. "Clients come to us with an application and we have all these different routes we can go down," says Corey Weber. "We don't want to 'shoehorn' anyone into a process that doesn't make sense." Having a range of capabilities gives Forecast 3D the flexibility to choose the right solution. Adding On The company's portfolio of options has recently expanded even further, with the installation of 12 HP Multi Jet Fusion 3D printers in its 3D Manufacturing Facility, just across the street from the Carlsbad headquarters. The speed of MJF coupled with an affordable material means that even injection molding designs can make sense in these machines, Donovan Weber says. Rather than batches of hundreds of parts, this fleet of printers can be tasked with volumes in the tens of thousands and up. The MJF 3D printers use a binder jetting-like process to print parts within build units that are removable from the printers. Binding and detailing agents are deposited onto plastic pow- der, and each layer is fused at once using infrared light to melt the areas held by the binding agent. This layer-by-layer (rather than point-by-point) fusion allows the process to be faster than laser-based 3D printing systems, and each layer takes the same amount of time to fuse regardless of complexity, according to HP. Forecast 3D also takes advantage of several other MJF benefits. Because the powder supports the parts as they grow, sacrificial support structures are not necessary. It's even possible to nest parts vertically as well as horizontally, filling the entire build vol- ume with individual, separate parts. All it takes is a gap of at least 3 mm in between them. The lack of support therefore allows for larger quantities to be produced at once, and enables greater de- sign freedom by eliminating the need to design in the supports and then remove them. And because heating takes place layer by layer with powder packed beneath the parts, warping is far less The Vekla watch cases are made from Nylon 12 and emerge from 3D printing a light gray, shown at the top. MJF parts can be dyed a limited number of colors over this base shade.

Articles in this issue

Links on this page

Archives of this issue

view archives of Additive Manufacturing - NOV 2017