Design, Print, Test, Repeat: Iteration in 3D Printing
Iteration of 3D printed parts. TOP: OEM part, BOTTOM left-to-right: PA12, Tough Resin, EPX 82, RPU 70.
The main advantage of 3D printing over traditional manufacturing is the ability to iterate quickly and cheaply. Design changes can sometimes be made in a matter of minutes and parts can be printed in as little as a couple hours–both without even leaving your office in some cases. This makes the technology revolutionary in its ability to spur innovation.
We’ve come so far in terms of our ability to efficiently design and print that we’re now comfortably in the next frontier of advancement: production of materials that can be used in end-use parts. For a long time, 3D printing was best used for prototyping parts that would eventually be produced using traditional methods and materials. Now, there are new materials hitting the market nearly every day, most of which are highly functional and durable.
These new materials are especially useful for industries such as automotive, aerospace, medical devices, engineering, energy, and many more. Industries such as these often require high-fidelity materials that can withstand stressors such as heat, water, solvents, pressure, tension, etc. None of which basic 3D printing materials such as PLA can hold up against. Luckily, there are several companies that have made it their mission to constantly be researching and designing new materials. Examples of these companies are Carbon, HP, 3D Systems, Stratasys, and Formlabs.
Carbon 3D’s EPX 82 material used to produce functional carabiner
The best way to utilize 3D printing for production of parts that need to be functional is through iteration. This means keeping true to the original purpose of the technology while also maximizing the new facets. Below is the step-by-step process we took to create new replacement automotive parts for classic Mercedes Benzs cars.
1. Reverse engineering and file design
Measurement of OEM automotive part
Before you can 3D print anything, you need a digital model file of the part. In the case of this OEM automotive windshield wiper part, we had to reverse engineer the original part by hand. Our team used tools to measure the part as precisely as possible to ensure that it fit correctly inside the vehicle and attached to an accompanying metal fitting. The end result was a geometrically accurate 3D printable STL file.
2. Prototyping in a non-functional material
Non-functional part printed in SLS PA12 nylon
To ensure that the geometry and size of the part was accurate, we first printed the part in a non-functional PA11 nylon material using HP’s MJF printer. This material is durable and accurate, making it a great option for printing a small, thin, hollow part. However, the powder-based material is also porous and rigid, meaning it wouldn’t be a good fit for final production because the part needed to withstand fluids and had to have a small amount of flexibility.
3. Functional material testing
Once we felt confident that the design was final, we then moved into printing the part in various functional materials. These materials were all resins that were designed to mimic traditional injection molding plastics such as polypropylene and thermoplastic elastomer.
We started with Formlabs’ Tough Resin, which had good strength, but not enough flexibility and we weren’t confident in its longevity when exposed to water and solvents.
Next, we tested Carbon’s new EPX 82 resin. This was excellent in terms of its durability and we felt confident that parts printed in this material could last several years. However, it lacked the slight flexibility required to fit the associated metal fitting piece.
Lastly, we tested Carbon’s RPU 70 resin. The material is known for its ability to flex slightly while also being extremely durable. Similar to the EPX 82, we knew parts printed in this material would last a very long time.
4. Final design updates
3D digital model of the part prior to going into production
Once we settled on the right material (RPU 70), we then had to make some final minor adjustments to the design file. Namely, updating the wall thickness so that the flexibility of the new part matched the OEM part. These are not edits we could have made prior to testing because we didn’t know the exact amount of flexibility each material would offer.
5. Production
With a final digital 3D model created and a material chosen, we were able to rapidly produce a low-volume production run of the parts here in NYC. This saved the client significant time compared to having to outsource the project to an overseas company that would likely have production minimums much higher than what he needed. In the future, our client will be able to have additional orders printed and delivered in a matter of days.
