Realizing 3D Printing’s Potential via Automated Post-Processing Tech
Michael Molitch-Hou posted on May 15, 2019 |

As the 3D printing space continues to transform into something that fits into industrial factory settings, we’ve seen materials expand, systems improve, and a trend toward automation. What has so far seemed to be the missing piece is an equal improvement in post-processing technologies.

One company looking to address that gap is Sheffield, UK-based Additive Manufacturing Technologies (AMT), which has developed a technology for modifying the surface area of a wide range of polymers, specifically with an eye toward 3D-printed parts. Not only that, but AMT aims to automate the entire 3D printing post-production process, from depowdering to inspection. To learn more, we spoke to AMT CEO Joseph Crabtree.

Post-Processing

Crabtree has a background in engineering, having spent the last ten years in traditional manufacturing, including in the aerospace and weapons industries. When he became exposed to 3D printing technology about three years ago, he also noticed the lack of attention paid to the post-processing space.

“Everyone’s either looking at raw materials or making a big splash about bigger, better faster printers, but this bit at the end—3D printing’s dirty little secret—wasn’t being addressed and we couldn’t believe it,” Crabtree recounted.

The PostPro3D is capable of modifying the surface of a 3D-printed object, smoothing the surface, sealing pores and strengthening the mechanical properties. (Image courtesy of AMT.)
The PostPro3D is capable of modifying the surface of a 3D-printed object, smoothing the surface, sealing pores and strengthening the mechanical properties. (Image courtesy of AMT.)

This led to the formation of AMT at the beginning of 2017. Using technology spun out of the University of Sheffield, AMT has created a range of products that modify the surface of 3D-printed parts without any manual intervention.

The flagship product, the PostPro3D, is a system that uses a proprietary “physiochemical process,” as Crabtree described it, in which a specialty liquid is converted into a vapor within a vacuum chamber. Parameters such as pressure, temperature and time can be precisely controlled to manage the surface modification of plastic parts.

Crabtree pointed out that the process doesn’t only smooth the texture of a component, but it can also strengthen a part and seals it as well (all with “no dimensional tolerance changes, no loss of fine features,” according to the CEO).

“Not only do we manage to smooth the part, but we’re also potentially improving the mechanical properties, such as elongation at break,” Crabtree said. Resolving all of the microscopic pores in 3D-printed parts thus makes them suitable for use in settings in which liquid penetration is an issue, such as in automotive or medical applications.

Parts are smoothed to the extent that they resemble injection molded components. (Image courtesy of AMT.)
Parts are smoothed to the extent that they resemble injection molded components. (Image courtesy of AMT.)

The liquid used for the PostPro3D is packaged in a consumable cartridge that is automatically re-ordered when the solvent runs out and relies on recycling used canisters. So far, over 85 different polymers have been validated for use in this process, including such standards as Nylon 12 and aerospace-approved materials like ULTEM 9085. Even elastomeric polymers, such as TPU, can be processed with the technology, despite the fact that other post-processing technologies, such as sandblasting, are too abrasive for such delicate materials.

The PostPro3D is currently available for sale and has a 100L chamber. AMT has also developed the PostPro3D Mini, with a chamber of only 30L, for use in universities, research labs and small manufacturing shops. The Mini is currently available for pre-order.

Beneath the Surface

While the most obvious form of surface modification is simply smoothing parts, the technology enables other types of alteration. This includes strengthening the Z-axis of a component printed via fused deposition modeling (a process for anisotropy is particularly problematic), as well as coloring parts, applying radio frequency coatings or carbon nanotubes.

For color parts, AMT is currently beta testing the PostPro3D Color, which has substantial benefits over existing methods for coloring parts—typically dying processes.

“Our technology reflows the semi-sintered or semi-porous surface of a polymer part to make it smooth and improve the mechanical properties. At that point, we have a great opportunity to introduce third party media,” Crabtree explained.

Color pigment actually penetrates the part during the smoothing process, so that it won’t leech off over time. (Image courtesy of AMT.)
Color pigment actually penetrates the part during the smoothing process, so that it won’t leech off over time. (Image courtesy of AMT.)

The PostPro3D Color, currently in beta testing, uses cartridges that allow users to mix colors or use a single color. Color pigment is introduced as an atomized mist while the component is being made smooth, allowing the pigment to bond directly to the polymer substrate. As a result, the color won’t wash or leech out over time. This is essential for parts made for aerospace or biomedical applications, which require specific colors for certain applications, such as tooling or orthopedic surgery guides.

“We’re not going after color matching,” Crabtree said. “We’re using color to add value and not just to create parts that are aesthetically pleasing.”

Post-Post-Processing

AMT isn’t solely focused on post-processing parts. The company is looking to improve everything that happens after the actual printing is complete. This includes unpacking and depowdering, for such technologies as MultiJet Fusion and selective laser sintering, as well as inspection. Moreover, all of this meant to be automated. 

“When we talk about targeting that $13-trillion industrial manufacturing market, we’re really applying our expertise in traditional manufacturing, such as injection molding and CNC machining, and applying that to 3D printing to get end-to-end, fully-automated, lights-out production,” Crabtree said.

A diagram of a complete Digital Manufacturing System, in which printed parts are automatically moved from a 3D printer, such as the HP system above, to post-processing stations, followed by automatic inspection and packaging for shipment. (Image courtesy of AMT.)
A diagram of a complete Digital Manufacturing System, in which printed parts are automatically moved from a 3D printer, such as the HP system above, to post-processing stations, followed by automatic inspection and packaging for shipment. (Image courtesy of AMT.)

According to the CEO, AMT has metrology, depowdering and end-to-end automation at work in-house. This automated Digital Manufacturing System, as the company refers to it, is in the process of being implemented with some customers. Among the technologies involved in this system are industrial robotic arms and machine learning, used to sort and recognize parts, as well as perform inspection based on qualified standards.

Customers will have the ability to purchase all or part of the system, from individual PostPro3D modules to a solution that covers everything after printed components are fabricated, depending on their needs. To learn more about AMT, visit the company website, or visit the booth (#656) at the upcoming RAPID + TCT show.


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