The Fraunhofer Institute for Additive Production Technology (IAPT) has shown how 3D printing can improve technical performance and manufacturing costs by redesigning the door hinges of luxury sports cars.
During the part redesign project, IAPT engineers optimized everything from the geometry of the door hinges to the build orientation and process parameters to maximize cost and weight savings.
Ultimately, this work aims to shed light on the less obvious factors that affect the cost of 3D printed parts, not just the geometry of the components themselves.
Simplify car production
The automotive industry is one of many industries that have embraced additive manufacturing over the years, using the technology for a variety of applications. To date, however, many use cases have been limited to small batches, as 3D printing has not yet provided the throughput of traditional automotive production technologies—without simultaneously keeping the cost of each part low. Thus, the Fraunhofer project may show that the technology as a whole is currently underutilized in the automotive sector and that high-volume series production applications are still in their infancy.
The first established use case is rapid prototyping, as the development phase of a new model can take up to five years. During R&D, several prototypes of parts are inevitably developed and tested, which means rapid design iterations with minimal lead times: this is one of the main selling points of additive manufacturing.
Automakers are also using 3D printed manufacturing tools, such as jigs and fixtures, to help with production and assembly workflows. There are even potential applications in aftermarket parts that were once cast but are now obsolete. The dynamic and flexible nature of 3D printing enables parts suppliers to print on demand, completely eliminating the need for physical component inventory.
3D printed door hinges
Before starting any design work, Fraunhofer engineers used part screening software developed by 3D Spark, an IAPT spin-off, to identify car parts suitable for demonstration studies.
In the early stages of the project, the team first identified the most cost-effective orientation for the components in the build room. Engineers considered the necessary support structures, and how many parts they could fit into a single build. This initial orientation optimization step resulted in a 15% cost savings compared to a 3D printed build without such considerations.
Next is topology optimization of the hinge arm itself. By removing unnecessary material and strengthening only the parts of the part needed to simulate force flow, engineers were able to reduce the weight of the hinge arm by 35 percent. Subsequent material savings and shorter print times resulted in a further 20% cost savings.
The Fraunhofer team also calculated additional cost savings associated with reducing post-processing (by reducing support structures) and choosing the best metal powder material for the job: 10% each.
Interestingly, the study found that even the build parameters used in the 3D printing process contribute to potential cost savings. For example, thicker layers, faster scan speeds, and deformation of the laser beam profile all help reduce build times, reducing printing costs by another 15%.
Ultimately, this cost-centric design approach allowed IAPT engineers to 3D print the hinge at an 80% lower cost than its 3D-printed counterpart without the same optimization. Compared to their CNC-milled counterparts, the project achieved cost and weight savings of 50% and 35%, respectively.