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How eggshell molding helps create Formula 1 racing parts

3D Systems' Figure 4^® eggshell molding solution gives BWT Alpine F1 Team unprecedented speed and flexibility to produce silicone and polyurethane parts for development and on-car use.

Speed is the name of the game in Formula One (F1) racing, both on the track and for everything behind the scenes. Using 3D Systems' innovative eggshell molding solution, BWT Alpine F1 Team has gained the production speed, quality, and flexibility it needs to innovate and accelerate development of silicone and polyurethane parts like never before.

Example of a universal gasket used in wind tunnel testing, designed to print in a batch of 36 on the Figure 4 Modular.

 

 

The Challenge: Rapidly produce molded elastomeric parts for wind tunnel and on-car applications
Conventional tooling methods for molding silicone and polyurethane parts are time consuming, often excluding them from consideration for F1 development. With only a few months between racing seasons and a push for nonstop progress year-round, speed of production, testing, and iteration is paramount. Given the grueling environment of the track and wind tunnel, there is no negotiating part performance either.

The Solution: Shortening development and manufacturing time
3D Systems' Figure 4 solution for eggshell molding enables the BWT Alpine F1 Team to produce a diverse range of high-quality molded silicone and polyurethane parts in record speed, providing unprecedented access to one-off and iterative parts using conventional molding materials. The straightforward workflow keeps up with the aggressive pace of Formula One, making it a tremendous asset to the team. For example, grommets or seals that would take multiple days or weeks using conventional metal tooling or vacuum casting can now be delivered in a single day using Figure 4.

BWT Alpine F1 Team runs multiple builds a day on its Figure 4^® Modular 3D printer for a wide range of casting tools for on-car parts and testing. Pat Warner, BWT Alpine F1 Team's advanced digital manufacturing manager, estimates that most 3D-printed eggshell molds print in just 90 minutes, with the largest builds taking up to three hours.

Flexibility across multiple applications
The team's productivity gains extend beyond same-day parts to the ability to address a wide range of applications using the Figure 4 eggshell molding process. The process relies on 3D Systems' Figure 4^® EGGSHELL-AMB 10 material, a process-optimized material for producing sacrificial tooling with the flexibility to deliver final parts in a range of silicones and polyurethanes. Figure 4 EGGSHELL-AMB 10 is a rigid plastic specifically engineered to fracture and break away easily after curing.

Eggshell molding is a sacrificial manufacturing technique that uses 3D printing to produce a thin, single-use mold that is injected with the final production material and then broken away.

 

 

According to Warner, this flexibility has been a major benefit: "We have a huge array of materials, and we can basically use all of them in the period of a day." This allows the team to look at a broad range of applications varying in stiffness, elongation, color, and other properties. "I can't think of another way we could make this many different components," Warner said. Most applications currently addressed using 3D Systems' eggshell molding solution fall into the categories of grommets, seals, and gaskets, which are used throughout the car.

Straightforward workflow
The straightforward CAD-to-molding workflow begins with sending the file to print within 3D Sprint^®, an all-in-one software for polymer 3D printing. The software's extensive toolset includes options for adding supports as well as managing the printing process. Once printed, BWT Alpine F1 Team post-processes the eggshells, which involves cleaning and post-curing them in the LC-3DPrint Box post-curing unit. This process takes roughly two hours and primarily consists of a 90-minute, hands-off post-cure.

Suspension seal and frame for testing produced with polyurethane casting using Figure 4^® EGGSHELL-AMB 10 and selective laser sintering in DuraForm^® PA, respectively.

 

 

After UV post-curing, BWT Alpine F1 Team coats the internal surface of the 3D-printed eggshell in a chemical releasing agent, and the shell is ready for polyurethane or silicone. Cure times vary depending on the material used and can take anywhere from 10 minutes to 24 hours.

Silicone bellows like the above are being produced at BWT Alpine F1 Team for the car's braking system.

 

 

Filling the eggshell molds is usually done in one of two ways: Either with the use of a static mixing nozzle, where the A and B components are mixed as the eggshell is being filled, or with a more standard syringe, where the components have been pre-mixed. A key aspect is that no specialist injection apparatus is necessary. Degassing of the material, to remove air bubbles, can be advantageous, but not always necessary.

Performance in a grueling environment
The performance demands on Formula One parts are extreme. Races take up to two hours, during which the entire vehicle is subjected to wildly varying temperatures, intense vibration, and brutal forces.

"It's a horrible environment to put something you haven't seen before yesterday," said Warner, "and we are always striving for perfection. We must ensure that all our parts perform the tasks they are given."

The parts produced using 3D Systems' eggshell molding solution meet this high threshold for performance. Warner said the surface quality is very good, which is especially important for aerodynamic parts. The ability to rapidly produce high-quality, high-performance parts also makes it possible for the team to now modify parts that were previously deprioritized due to the extreme time constraints of the sport.

The Results: Unprecedented access to high-performance molded parts for record-speed development

• Same-day digital production -- compared to weeks with conventional methods;
• High-quality on-car performance -- withstands extreme temperatures, vibrations, and forces;
• Broad material versatility -- with a range of casting silicones and polyurethanes; and
• Increased capacity for innovation -- to evolve previously deprioritized systems.

Learn more about 3D Systems' Figure 4 EGGSHELL-AMB 10 material at https://www.3dsystems.com/materials/figure-4-eggshell-amb-10.

Source: 3D Systems

Published July 2023

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