The fit for digital fab

Posted on Sep 9, 2010 :: Cover Story
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Posted by , Insight on Manufacturing Staff Writer

A visit to an art fair three years ago gave Melron Corporation President Debbie Flood a brush with technology that would transform her manufacturing business. Melron makes casted parts for window and door manufacturers.

With the housing market in recession for two years and cheap imported parts cutting into her market, Flood says Schofield, Wis.-based Melron might not be in business today had it not adopted the technology she learned about at that Madison art fair: digital fabrication. With digital fabrication, special equipment outputs parts directly from a three-dimensional, computer-aided design model. The technology is used for rapid prototyping, but also is making headway as a means of creating tooling and customized parts.

The sculptor Flood met at the art fair was using digital fabrication in his small foundry, but Flood soon realized such gear could be used to create the patterns for the sand-casting that is the cornerstone of how Melron makes parts. “I looked at it, and just thought: this is the future of manufacturing,” says Flood.

Flood began investigating digital fabrication and made a deal to buy a used fused deposition modeling or “FDM” machine that makes parts by laying down and curing plastic layers. The move required Melron to bring in an employee with expertise in 3D CAD, but it eliminated the need to outsource pattern making to machine shops that cut the patterns from metal. Melron continues to sand cast and  finish metal parts in a conventional manner.

Flood says moving pattern making in-house with digital fabrication slashes cycle time. Before, a machined pattern might take six weeks to produce, but now Melron can go from concept to finished part in as little as two weeks.

“I would contend that in this difficult economy – and still having to do a lot of product development – that we might not be in business had we not purchased this machine because it allows us to turn projects very quickly,” says Flood.

Digital fabrication is beginning to catch on among manufacturers in the region, including for the production of patterns, tooling and parts. It’s also being used for production by a major dental lab. In addition, the New North is home to an educational center for the technology: the Fab Lab at Fox Valley Technical College, one of 17 such labs worldwide.

With digital fabrication and the related concept of “additive manufacturing,” the machines form parts directly from digital data. There is no creation of tooling or molds, and no painstaking transfer of design data into machine code. Once the 3D model is generated, a standard file format (usually STL, for Standard Triangulation Language) is read by the machine to fabricate a part. “It’s like you are almost printing the object,” says Jim Janisse, development manager for the Fab Lab at FVTC. “You are simply sending the machine a digital description of what you want to make.”

But for all the excitement about digital fabrication, it remains an emerging technology that some observers say doesn’t suit every need, requires special equipment and training, and isn’t cost competitive with more conventional techniques when it comes to producing less complex components in high volumes. For now, the sweet spot for the technology appears to be prototyping and the rapid production of patterns and other tooling. At the same time, there are misconceptions about the technology, such as that it can only produce paper-based parts or fragile plastics.

“We are seeing digital fabrication being used to produce real parts for limited use – not just for prototyping,” says Peter Bilello, president of CIMdata, an Ann Arbor, Mich.-based research firm that tracks engineering technology. “It has become good enough to do that.”

Bilello says that for cost reasons it’s still cheaper to produce most production parts using conventional techniques such as casting or machining. He also says digital fabrication machinery is usually limited in the size of a component it can produce. This is because the equipment typically has compartments of finite size where the forming takes place.

Fused Innovation is a Neenah-based company that is a digital fabrication service provider, and currently has three different types of additive manufacturing machines. David Kettner, technical director, agrees there are plenty of misconceptions about the technology, including that it only can produce thin-skinned prototypes. One of the machines at Fused Innovation – a laser metal deposition machine – can form hard metal parts or even fuse harder metals on softer metals. “The strength characteristics depend on the technology you are using,” says Kettner. “With laser metal deposition, we have made tool steel components, stainless steel components, and titanium components.”

Part of the problem might stem from flashy video examples of the technology that exist on the Internet. Do a Google search for digital fabrication, and you are likely to spot a prototype costume design from an Iron Man movie. But here in Wisconsin, digital fabrication is less about flashy, origami-like figurines, and more about industrial necessities like patterns for making real parts.

Time compression

Taking the leap into digital fabrication wasn’t an easy decision, says Flood. The FDM equipment – even used – cost roughly $200,000 at the time, and carries a $20,000 annual service contract. Melron would also need to find a technician skilled in 3D CAD. Other digital fabrication gear can cost much less today, but as Flood warns “There can be quite an investment in the equipment, and a knowledge-base that goes with it.”

It was a tough decision, says Flood, but one that she is glad the company took, primarily because it takes big chunks of time out of developing unique casted parts. Flood says it usually takes the FDM machine about three to five days to fabricate a pattern

. Digital pattern making makes it easier to get the casting just right without going back and forth to a pattern shop, says Flood. Additionally, the FDM machine is able to quickly produce a variation in the gates that allow metal to flow into a casting.

The machine also can fabricate prototype parts. Because the ABS material has fairly good hardness, customers can assemble a prototype into a window assembly to test it. All of this, Flood says, helps her company land jobs.

Another Wisconsin company using digital fabrication to accelerate production is Griffin Industries, a pattern and machine shop in Green Bay. The company uses a 3D printer for multiple purposes, says Jonathan Krouth, president.

The primary use of the machine, from a vendor called Z Corporation, is to create plaster-based models of parts that will later be casted and machined in metal. The mockups allow Griffin’s staff to explain to customers how a design might need to be tweaked to improve the manufacturability of the casting or machining process. An issue that might not be readily understood by looking at a 3D image (such as how a protrusion on a part might impact casting) can be more easily communicated by examining the physical model.

While the concept models are plaster-based, they have a hard-coated surface that makes them suitable for other purposes, such as testing the fit-up of a mock part within a customer’s assembly, or in some cases, for producing patterns for sand castings that don’t require a high degree of complexity. Griffin also uses the machine for another purpose: to help figure out the best way to build the fixtures that will hold a casted metal part that needs to have some machining done on it.

“In some cases, we will build our fixtures using these models long before the castings get here,” says Krouth, “so we are able to gain additional time compression.”

All these digital fabrication uses align with Griffin’s focus of helping manufacturers quickly produce complex parts. Krouth doesn’t see digital fabrication as displacing conventional casting and machining as the most cost effective way to produce most larger or complex metal parts in higher volumes, but does recognize its value as a way to speed up time to market. “Time compression is what we are selling,” Krouth says. “By utilizing this rapid prototyping technology we are able to reduce that timeframe because we can shorten the communication cycle between the foundry, the machine shop and the customer design team.”

 Best uses

Even while digital fabrication is proving itself in certain areas, it may not suit every production need. John West, president of Fox Valley Metal-Tech, a Green Bay-based custom sheet metal fabricator, says the technology is interesting, but wouldn’t work well for his company.

Typically, says West, customers order in fairly small volumes, but demand turn around in as little as a week. What’s more, they may provide only a two-dimensional drawing. “If I don’t get a 3D model from the customer, they have maybe a 2D print, and they say, ‘now turn it around for me as quickly as possible.’”

In this environment, it would be hard to get payback on the time and effort of creating a 3D model and digitally fabricating parts, says West. Getting into it, he adds, also would require adding a 3D CAD expert. “It’s very difficult to be competitive in our market with that particular type of equipment,” says West.

Even proponents say there are times when the technology isn’t the best choice. Fused Innovation’s Kettner says one key thing to consider is how much material needs to be cut away under a “subtractive” technique like machining. “Look at it this way,” says Kettner, “if I’m looking at a part that is essentially a square block of metal with a groove in it, it’s going to be cheaper to start with a square block of metal and cut a groove in it.”

But for many complex smaller parts with unique surfaces, shapes, or voids, digital fabrication might be ideal. The technology can even incorporate movable shapes melded into one component in ways that can’t be machined. “There is a point where adding material to something is better, more capable, or less expensive than subtracting the materials away,” Kettner says.

Others involved with digital fabrication believe its biggest barrier to adoption may be reluctance to try new techniques. Bill Murphy, vice president with Motion Products, a Neenah-based company that uses the technology to produce parts for vintage cars, says it’s a misconception to think digital fabrication is just for prototypes. “We are realizing it can be used for small production runs,” he says. “The technology can be pushed there.”

Manufacturers in the region need only look to related sectors to see examples of production use of digital fabrication. At Lord’s Dental Studio, a DePere-based dental laboratory, a 3D printer is used to fabricate the core or “base” of false teeth out of a resin-based, blue-colored polymer, according to Kris Van Laanen, VP of research and development. This blue base is then finished with other materials to look like a normal tooth.

Before moving to digital fabrication three years ago, the bases for crowns, implants and partial dentures were hand-sculpted by technicians under strong magnification. The training for the process could take a year just to be able to produce a crown, and years more to master all aspects, says Van Laanen. “We made beautiful crowns that [older] way,” he says. “It just took a lot of labor and experience. And the consistency was difficult to maintain.”

Van Laanen estimates that only a modest percentage of dental labs are using scanning of dental models and digital fabrication for crown production today – perhaps 10 percent – but he foresees rapid uptake as more labs recognize the training and production efficiencies. “This system does a lot of thinking for you,” he says.

Flood is confident Melron did well to move early with the technology. “I do think you can get behind,” she says. “We’ve invested heavily in recent years in design technology, and like I said, I’m not sure we would be in business had we not done that, because it has allowed us to develop products economically, and very quickly.”