The best of both worlds

For mass producing identical parts, injection molding is king. For a rapid prototype or small run of custom pieces, nothing beats a 3D printer. Try to operate between these worlds, and you'll have to make some compromises. Or will you?

Between mass production and rapid prototyping lies a world of untapped potential. A market gap that neither injection molding nor existing 3D printing technology can serve without becoming cost prohibitive or simply unfeasible. "Smaller batch sizes can't offset the cost of building molds," explains Steve Chillscyzn, CEO of Evolve Additive Solutions. "On the other hand, conventional 3D printers are too slow to scale up effectively."

Evolve set out to fill this gap in 2017. After years of intense development, the Minnesota-based startup has arrived at a solution they say is faster than any other production-scale additive technology on the market today. To complete its first commercial systems, Evolve was looking for a reliable automation partner who shared its vision. They found it in Hartfiel Automation, a B&R engineering and distribution partner headquartered in Minneapolis.

The platform Evolve created is called SVP, which stands for scalable volume production. At the heart of the SVP platform is Evolve's revolutionary new additive technique called selective thermoplastic electrophotographic process – or simply STEP. In theory, the STEP concept sounds simple enough: Three-dimensional parts are printed as a series of two-dimensional slices, which are stacked and fused into a fully functional production-grade part.

The STEP process begins with a well-known 2D printing technique – electrophotographic deposition. As feedstock, it uses familiar engineering thermoplastics like ABS and Nylon, which are micronized into fine particles through a proprietary process. A proven technique using proven materials, combined in a way that's never been done before: That gave the Evolve platform the speed it needed to bring additive's flexibility and short lead times to production scale.

To make functional parts, however, the Evolve platform would have to deliver not just quantity, but quality as well. "To make sure our customers get the performance they expect from their chosen materials, we needed our control solution to ensure extremely precise positioning and timing as the slices are aligned and fused together," explains John Lees, Evolve's vice president of engineering. "That reliable, repeatable performance is exactly what we got through our engineering collaboration with Hartfiel and B&R."

The alignment and fusion steps feature a total of six motion control axes: two that control the speed and tension of the transfer belt, and two each for horizontal and vertical movement of the build plates. "Precise positioning and timing are critical for the stacking process," says Scott Albrecht, vice president of advanced control technologies at Hartfiel. "And the microsecond triggers and ripple compensation on B&R's ACOPOS P3 servo drives helped us achieve really great results."

Just like in injection molding, precisely controlled cycles of temperature and pressure are the key to ensuring consistent high quality results. "The B&R Automation PC 3100 gives us plenty of computing power to coordinate all the complex motion and temperature control tasks, while taking up very little space in the cabinet," says Albrecht.

A surface scanner checks for imperfections, which are then compensated by depositing more or less material at specific points when printing the next layer. The result is a fully dense part with consistent properties in all directions. "Our parts have an average surface roughness of only five microns," says Lees. "Normally that kind of finish might require sand-blasting, but thanks to the control precision we've achieved together with Hartfiel and B&R, we're able to do it with no post-processing at all."

Having developed two early iterations of its platform using other control systems, Evolve turned to Hartfiel in 2020 to complete its first commercial system. "As much as the technical factors, what really sealed it for us was confidence in the partnership," says Chillscyzn. "From the level of engineering engagement they offered to the understanding Hartfiel and B&R demonstrated for what we're about and where additive is headed."

Hartfiel collaborated with Evolve engineers for months of intense development to tune the linear motors, implement the high-precision controls for web speed and tension, and synchronize the movement of the build plate. Hartfiel even provided a full electrical schematic and panel layout and handled UL certification. "It wasn't just here's a box of parts and off you go," recalls Lees. "They've been deeply involved throughout the project – and continue to deliver rapid turnaround for ongoing upgrades and adaptations."

"This is the kind of story I love to hear from our partners around the country," says Patrick McDermott, president of B&R North America. "It highlights exactly what we're looking for: people who share our passion for solving engineering challenges. It's one thing to offer world-class products. But what's really exciting is to see a team bring that potential to life and accomplish something that's never been done before, like Hartfiel has with Evolve."

Technology potential also played a role in the supplier switch. "We saw an even higher ceiling for where we could go with B&R in the future," notes Lees, citing plans to use B&R machine vision to further refine stacking alignment as just one example. "With partners like Hartfiel and B&R, we are excited to be leading the way into a new era of additive manufacturing, where the technology will continue to advance by leaps and bounds."