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Large-format 3D printers eliminate ‘stitching’ parts together

The bigger a 3D printer’s build volume, the greater the chance it can build monolithic objects

3d printing

Seats are an example of what can be produced on a large-format FFF-style printer. BigRep

The Stratasys website states that company founder Scott Crump was looking for “a simpler way to make a toy frog for his daughter” when he invented fused deposition modeling (FDM). In 1988, he patented what was in essence a hot glue gun under CNC control, a technology that has since become one of the pillars of the 3D printing industry.

The FDM patent expired in 2009. This led companies such as Prusa and Ultimaker to develop competing 3D printers, although none can refer to their technology as “FDM.” The name remains trademarked, and those who don’t hand out Stratasys business cards generally refer to the technology as FFF (fused filament fabrication) or filament.

Stop the Stitch

Unlike Stratasys, few FFF printer builders offer supersized equipment for producing ever-larger 3D-printed objects. One that does is Berlin-based BigRep.

Frank Marangell, president of BigRep America Inc., Wilmington, Mass., cites several advantages of large-format FFF machines. Chief among them is the ability to build monolithic parts.

The company’s largest machines have 1-meter-cubed build chambers. “This allows manufacturers to print larger parts as a single piece, rather than gluing and pinning several smaller ones together. It also provides greater flexibility,” said Marangell. “For example, there are fewer restrictions on part orientation during the build process like there is with smaller machines. This makes it easier to print critical part features in the vertical direction, or Z-axis, providing greater accuracy.”

What types of large parts do companies print? Marangell said the equipment is used by furniture makers, architectural firms, toy manufacturers, and the automotive industry, where it’s used to print prototypes of grills and dashboards as well as jigs and fixtures for the factory floor.

Owning a big machine doesn’t mean a manufacturer is limited to printing big parts, though. Marangell points out that many customers leverage a BigRep machine’s 1,600-sq.-in. print bed, which is 15 to 20 times larger than most FFF machine beds. They print entire production runs of smaller parts in a single build then, as the need arises, they change over the machine to print large workpieces.

Big Constraints

Detractors of FFF machines—whether they be small-, medium-, or large-format printers—say that the technology suffers from several deficiencies. Delamination historically has been a problem with FFF equipment, and resolution and accuracy often are insufficient for fine details, particularly as parts and machinery get larger.

Furthermore, spool size can be a constraint when producing large workpieces. Without the means to sense an empty spool of material, automatically stop the build until the spool has been replaced, and then pick up where the previous spool left off, users might be left with scrapped parts and significant loss of production time as the machine prints air.

Marangell said industrial-grade FFF printers have addressed these concerns. BigRep and competing large-format printers feature automated spool management, as well as sensor-based process monitoring, multiple- and large-reel capabilities, and different nozzle sizes for printing fine details or maximizing deposition rates.

additive manufacturing

The team at Solaxis has built a business around large-format FDM printing. Solaxis

Ingenious Manufacturing

Someone with extensive large-format printing experience is François Guilbault, president of additive manufacturing firm Solaxis Ingenious Manufacturing Inc., Bromont, Quebec. The 10-person Solaxis team operates two Fortus 400mc and seven F900 Gen III FDM printers from Stratasys, the latter with a build envelope of 914 by 609 by 914 mm.

Solaxis, founded in 2010, serves a variety of industries, Guilbault explained. Given its proximity to Bombardier Aerospace in Montreal, aeronautics is high on the list, but the company also prints parts for air-quality and industrial equipment manufacturers, among others.

Notable projects include a 28- by 28- by 12-mm thermoforming die made of PEKK, as well as flooring panels and other parts for recreational vehicles (RVs), some of which were so large they had to be spliced together at multiple points. Nearly two-thirds of the objects the company prints are end-use parts; the rest are functional prototypes or specialized tooling.

Guilbault noted that, done properly, splicing is not something to be avoided, and the techniques used to splice are similar to those found in autobody repair shops. In the RV flooring example, the joints were stronger than the surrounding material. He added that sometimes it’s much faster to print a part in sections and assemble it afterward.

“Warpage and overheating can be a problem with larger parts, particularly on higher-temperature materials such as PEKK and Ultem,” said Guilbault. “There have been some hardware advancements recently that help to avoid these issues, but build strategy also plays a role.”

Strategy also plays a role when 3D-printing nylon and other moisture-sensitive materials. In these applications, it’s crucial that the air in the build chamber remain as dry as possible.

“That said, good equipment is clearly important, but success with large-format printing depends a great deal on your part design skills and the ability to anticipate any potential problem areas,” said Guilbault.

About the Author

Kip Hanson

Kip Hanson is a freelance writer with more than 35 years working in and writing about manufacturing. He lives in Tucson, Ariz.