Structur3d Innovation Brings the Factory to Your Desktop

If you ever wanted a factory in your home, you are in luck. Structur3d has unveiled the Inj3ctor platform, a low-cost desktop injection molding tool that uses 3D-printed molds. Andrew Finkle, co-founder and CTO of Structur3d, discussed the Inj3ctor’s launch with engineering.com.

Founded in 2013 in Kitchener, Ontario, Structur3d began with the Discov3ry Paste Extruder, which was funded through Kickstarter in 2015. It featured an add-on for desktop fused deposition modeling (FDM) printers that allowed much greater flexibility in the choice of materials, aside from just plastics.

“The Discov3ry is compatible with most open additive manufacturing platforms,” Finkle said. “It gave 3D hobbyists the option of using thousands more materials with their plastic 3D printer thanks to this upgrade. We currently have thousands of hackers, scientists, engineers and educators using the Discov3ry technology in their workflow.”

Through customer feedback and collaboration with Ultimaker, the company expanded its offerings to include pre-integrated printer systems, the Discov3ry Complete and Discov3ry 2-Part Complete.

The Canada-based organization now aims to overcome challenges preventing 3D-printed rubber parts from meeting necessary manufacturing standards, by bringing 3D printing and desktop injection techniques together with factory-grade materials.

Most 3D-printing applications call for rigid materials. Typically hard and brittle thermoplastic materials, such as polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS), offer very limited applications. Sometimes, more flexibility and strength are required.

Elastomers, which are rubber-like materials, try to fulfill that requirement. However, the flexibility comes with drawbacks. FDM 3D printers, the most popular type, extrude heated filament so that it can melt and be brought into the requisite shape. This does not work with elastomers, as the print head would be blocked. Additionally, elastomers cannot be used in functional parts due to their fragile nature.

Other leading rubber parts production processes are casting and traditional injection molding. Casting involves premixing precursor materials and pouring or dipping into the desired shape. Though it is a reliable process, it results in a lot of wastage of time and materials. As for traditional injection molding, the mold has to be tailored to one specific part, making it very expensive. This makes it feasible for the production of thousands of units but not suited for rapid prototyping of that same part during pre-production design.

While the original Discov3ry extruder was able to address some of these issues, there remained a larger problem. The structural integrity of extruded parts along the Z-axis (i.e., the height) was weaker than that along the X- and Y-axes.

“Due to viscosity and the slower ‘hardening’ times compared to plastic, silicone parts are limited in the surface quality that can be achieved through direct writing of the material, even seeing some slumping,” Finkle explained. “Direct writing of silicone can lead to slow print times—about five times slower than plastic—and reduced surface finish quality.”

Therefore, the demand for rapid prototyping of manufacturing factory-grade rubber products remained unfulfilled. Structur3d stepped in to fill that gap.

Finkle, along with his co-founder and CEO Dr. Charles Mire, received a lot of interest from customers about the possibility of making rubber products.

“We were aware of the issues related to rapid prototyping and manufacturing of rubber parts,” Finkle said. “We understood the material property limitations of plastics and rubber alternatives in applications for automotive, aerospace, food science and biomedical science.”

Structur3d combined 3D printing and desktop injection molding, which expanded its material capabilities by creating a “technology stack.” Hence, the Inj3ctor platform was born.

“We worked closely with customers like Stanley Black and Decker to fully understand the issues they were facing for rubber items requiring small-scale manufacturing,” Mire said. “Existing technologies were not adequate to solve these issues, and we developed the Inj3ctor System to fill that gap.”

The Structur3d team was accepted into the first cohort of the Stanley + Techstars Additive Manufacturing (Industry 4.0) Incubator in Stanley’s newly formed state-of-the-art “Manufactory” in Hartford, Conn.

“Through our time with Stanley, we worked hand in hand with their product engineers to develop new product prototype solutions,” Finkle said. “In one example, we helped develop a customized gasket for weatherproofing, and another was to help improve an existing product line that traditional technology production costs could not justify. One of the most important Inj3ctor product features to Stanley was the ability to prototype and develop with the same materials they use in production.”

“As a team of scientists and chemical engineers, we took a materials approach to 3D-printing technology and expanded the printers’ material capabilities beyond standard plastics,” Mire said. “Our Inj3ctor platform spotlights our shift to industrial manufacturing markets and demonstrates how additive manufacturing can lead the way toward the factory of the future.”

The Inj3ctor takes the best parts of the existing technologies and combines them effectively. It couples 3D printing with desktop injection molding and automates the casting process to reduce wasted materials and technician time required for higher and more controlled throughputs.

“It also makes the process viable for short-run, complex geometries and customization and personalization of production parts,” Finkle added.

The platform can produce new products with factory-grade rubber materials using 3D-printed molds to inject two-component (2K) flexible materials, such as silicones and polyurethanes, into customizable shapes. The detailed molds are designed using CAD software and 3D printed using standard, durable or dissolvable plastic via an Ultimaker S5 3D printer. Injection molding imparts truly isotropic properties to the rubber components, thus resolving the problem of “slumping” along the Z-axis.

Owing to the platform’s open material system, users can customize thousands of liquid rubber materials, including silicones, urethanes, epoxies and composites. They can achieve the desired durability, flexibility and curing time before programming the mixing ratio and injection volume. Based on these parameters, the Inj3ctor fills the 3D-printed mold to create a customized, flexible product. Reducing costs and procurement risks, this process is well-suited to small-batch on-demand manufacturing of rubber prototypes and end-use parts.

“It can automate the mixing process and filling of molds, allowing rapid production of high-quality rubber parts in a fraction of the time,” Finkle said.

The operation of the Inj3ctor system can be described in four steps:

1. Design the mold.
2. 3D print the mold.
3. Inject the mold using the Inj3ctor.
4. Release the finished product from the mold.

Despite the benefits, there are still hurdles that the Inj3ctor technology might face. The finish of a 3D-printed mold may not be smooth enough for high-definition parts and may require some post-processing to achieve the necessary finish. Additionally, while this style of injection molding may be appropriate for rubber materials, it may not work for molding high-temperature plastics.

Two other firms that have developed similar technologies are AddiFab and Collider, both of which use a stereolithography-style process to create disposable molds for injection molding. While AddiFab’s molds are put into an injection-molding machine, Collider’s molds are dissolved during the 3D-printing molding process within a single machine.

Several new rubber-like materials have been developed recently. Fillamentum Industrial, a Czech manufacturing company, has introduced a range of flexible resins called Flexfill thermoplastic elastomer (TPE). These are appropriate for prototyping, packaging, medical products and components, such as gaskets and seals.

3D Systems, operating out of the U.S., introduced its Figure 4 RUBBER-65A BLK elastomer. The material exhibited a high level of flexibility and durability, making it applicable for air and dust gaskets and seals for electronics.

Another U.S.-based 3D-printing resin specialist, Adaptive3D, developed ToughRubber—a resin-based soft rubber-like material—in collaboration with Dutch nutrition and materials multinational DSM.

GoProto, a prototyping service provider, introduced a new 3D-printing service called 3DElastroPrint, specializing in producing rubber-like parts based on a flexible, lightweight thermoplastic polyamide (TPA) optimized for HP’s Multi Jet Fusion (MJF) systems.

Other manufacturers offer semi-flexible filaments, such as MakerBot’s Flexible Filament or the new TPU 95A from Ultimaker. Though not as rubber-like as the ones above, they still provide some flexibility. For instance, the MakerBot filament becomes flexible when placed in hot water, allowing it to be reshaped before the material cools and becomes rigid again.

According to Structur3d, anyone and everyone can use the Inj3ctor. The benefits of the platform are being heavily explored in numerous industries, including automotive, industrial products, aerospace, academia, energy, biomedical and various consumer products in which customization is desired. Due to the chemical and mechanical properties of rubbers, the parts make excellent candidates for applications in vibration resistance and comfort; human touch points, such as wearables and cushioning; and personalized medical devices.

The platform removes expensive and time-consuming stages of manufacturing rubber products, such as hand-casted molds and costly mass production tools. As large manufacturers look to the future of custom, on-demand manufacturing, the Inj3ctor could open the door to firms thinking about integrating additive manufacturing (AM) technologies into their workflows. Structur3d is well-placed to supply the technology capable of meeting the demands.

The first batch of Inj3ctor platforms shipped out at the end of last year to Industry 4.0 manufacturers. Included within the Inj3ctor Platform Bundle were the Inj3ctor, an Ultimaker S5 3D printer and a selection of pre-filled cartridges of silicone and polyurethane. Finkle detailed the Structur3d team’s plans for the future: “With the successful delivery of our first Inj3ctor shipments in late 2020, we are now ready to expand the capabilities of our customers. The focus in 2021 will be on education and new material partnerships. For education, we want to document and share what can be done with the Inj3ctor.”

Structur3d is further collaborating with Ultimaker to develop a process to 3D-print molds of soluble polyvinyl alcohol (PVA), another synthetic polymer.

“We are also continuing to develop partnerships with material vendors in order to provide the best production quality rubbers to our customers,” Finkle said. “We are very excited to see what creative processes our customers will build with the Inj3ctor Platform.”