How Braskem Leveraged 3D Printing for Injection Molding
Moldmaking is used across industries by product designers, entrepreneurs, and teachers to create short production runs, prototype complex molds, test production in end-use plastics, and more. Injection molding specifically is a versatile process that is used to produce high volume parts.
For those using injection molding, combining mold making with a Formlabs 3D printer gives engineers and designers access to affordable and quickly produced molds. As a supplement to the molding process, 3D printed injection molds tend to be both faster and less expensive than CNC milling and other traditional forms of mold making.
Formlabs spoke with Technology Development Engineers Michelle Sing and Jake Fallon, Additive Manufacturing Process Engineer Collin Azinger, and Global Additive Manufacturing Technology Manager Fabio Lamon of Braskem, one of the world’s leading petrochemical companies, to talk about their first foray into injection molding with a 3D printed part.
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Direct Printing or Injection Molding?
“Remote printing on the Form 3 was very important. Being able to start a print at home really speeds up the process.”
Jake Fallon opened his inbox to see an urgent email from one of Braskem’s VPs—with COVID-19 spreading, the company needed to create thousands of straps for masks to protect their global workforce. What could Jake do in 48 hours with the equipment in Braskem’s tool chest?
When Jake met with his coworkers on the Braskem additive manufacturing team, their first thought was to 3D print the straps directly using a fused deposition modeling (FDM) printer. However, even with the speed of FDM, they estimated it would take 17 minutes per strap. Given the request called for creating thousands of straps, this would take far too much time. In addition to their benchtop FDM printers, Braskem’s Pittsburgh Tech Center also had a Formlabs Form 3 and injection molding equipment. This seeded an idea, but also many questions.
What can injection molding offer? Injection molding is widely known to be an efficient and quick way to mass produce parts, but there was early skepticism around creating a plastic 3D printed mold for their electric powered Cincinnati Milacron 110 Ton Roboshot machine. Could a plastic mold hold up to the pressure of the machine? Would it break after 50, 500, or even 1,000 shots?
Braskem turned to High Temp Resin, a Formlabs material capable of printing molds and inserts to produce parts in production materials using processes like injection molding. High Temp Resin V2, the most recent formulation, has a heat deflection temperature of 238 °C @ 0.45 MPa. This was important because the team had to keep pressure as low as possible to reduce risks of breakage on the mold gate. This required increasing temperature for lower viscosity; High Temp Resin is the only resin available from Formlabs that could handle the higher temperatures required for this specific mold.
The team designed a mold that prints two straps per shot. They took their first 3D printed mold off the Form 3, removed supports and put it through a minimal sanding process. As the shots started firing, the straps began to pile up. A flexible low viscosity polypropylene was injected into the mold in order to reduce pressure in the cavity and extend the lifetime of the 3D printed part.
The very first iteration of the mold held up to 5-ton clamping pressure, 20-second cycle time, injection speed of 0.5in/s, and holding pressure of 5000 psi for approximately eight seconds. Average molding temperatures were about 230°C.
“We use High Temp Resin V2 at 50 microns. The quality was super nice, the resolution was fantastic. If you picked up the strap off a table, you would have a hard time differentiating it from a part made with a metal mold.”
The team recommends using a standard mold release spray, which gave them 40 to 50 shots per spray. The effectiveness of the spray is improved by printing at 50 micron layer height, creating a super smooth surface finish which allows for the parts to be easily removed from the mold. There was no additional cooling needed for the 3D printed mold; there was no trace of reaction between the injected material and the printed resin.
Without access to 3D printing, Braskem would have had to outsource an expensive metal mold, costing the team money and valuable time. By leveraging 3D printing, the team was producing thousands of straps within a week of receiving the VP’s email and preparing them for shipping to offices around the world.
Design Iterations and Injections
“We reduced material use by 28% through design iterations”
With the Roboshot machine creating straps, Jake went back to his CAD software to upgrade the mold’s design, with a focus on improving and strengthening the gate. Jake also wanted to improve the flow inside the cavity in order to extend the lifetime of the mold, and to avoid flashing. In the process of improving the mold, he was able to reduce the amount of High Temp Resin used by 28%, saving the company money and reducing print time.
Although mold V1 worked on the first attempt, mold V2, now with a stronger and larger gate, was designed to withstand thousands of shots. The new mold can withstand at least 1,500 shots before needing to be replaced, and enabled the team to fulfill the strap orders. Creating four straps per minute, the new and improved mold was exactly what the team needed to complete the task.
The Braskem team sees dozens of potential uses for 3D printed molds in the future. Cheap molds, which cost less than $100 per unit to create, could help clients that are looking for small batch runs. An example would be seasonal packaging to make a product stand out on the shelf. Before, smaller firms would not be able to justify the cost of metal molds and tooling. But 3D printing molds that hold up to thousands of shots could open new marketing and branding opportunities.
“Time was the number one benefit. We were testing the mold in one week, and then in one day created a second design which delivered significant improvements.”
The Braskem team was impressed with how injection molding expanded the capabilities of their 3D printer beyond rapid prototyping and into the realm of production. With hundreds of materials available for injection molding, Braskem has long been a reliable partner for firms using injection molding for mass production. They also sell over 300 materials for thermoforming, blow molding, and other manufacturing processes which could benefit from 3D printing molds.
In the future, the team is interested in injection molding possibilities with the Form 3L, given its ability to create large parts. According to Jake, “the 3D printed mold was near the limits of the build volume for the Form 3; we are really excited to explore the opportunities that the Form 3L enables”.
Download our free white paper or watch the webinar for a detailed process workflow, design guidelines, and other best practices for using 3D printed molds in the injection molding process and see additional real-life case studies with Novus Applications and Holimaker.