Metal additive manufacturing, or 3D printing as it better known, is set to revolutionise the automotive sector, bringing numerous benefits, as well as innovations in part design and processing.
Already examples are emerging, such as the 3D-printed titanium brake caliper for the Bugatti Chiron. Produced as a single unit from titanium through the layering process in the build chamber of an SLM 500 multi-laser machine, it features a tensile strength of 1,250 N/sqmm and a material density over 99.7%. On testing the parts, Bugatti found the 3D-printed components sustained strength and retained stiffness amid the high temperatures witnessed at the speeds of more than 375km/hour achieved by these high-performance sports cars.
When BMW redesigned the folding mechanism of the BMW i8 Roadster and built it in the metal-powder bed fusion chamber of an SLM Solutions laser machine, it found the part to be 10 times stiffer than the plastic injection moulded counterpart. It was also 44% lighter as it was built from AlSi10Mg. Traditionally the folding mechanism of the i8 Roadster’s soft top is cumbersome, loading the car with unwanted additional weight, and taking up boot space. The new folding mechanism reduces all of these unnecessary issues. BMW also optimised the design specifications so that the part can now be produced in greater quantities, since the reduction in support structures enables stacking of 238 parts per platform, realising a significant economic cost saving.
Dedicated teams from SLM Solutions, with strong R&D applications knowledge and service experience, work closely with companies on specific customer development projects. One such project, the LightHinge+ project, demonstrates not just the usual benefits of 3D printing in terms of weight reduction and efficiencies, but also addressed the safety requirements of parts when vehicles become involved in a collision. The LightHinge+ project combined three organisations – EDAG Engineering, voestalpine ADM Centre and Simufact Engineering – in the redevelopment of a vehicle hood hinge with stringent specifications and the requirement for weight reduction.
The exacting safety and functionality demands imposed on engine hoods demonstrate how complex the parts actually are. The response of the hood hinge is critical in the event of a pedestrian accident, as within a fraction of a second the hinge extends the distance between impact and engine components by raising the hood, thereby reducing pedestrian injury. However, complex kinematics are involved to trigger this instantaneous response. In the past this has entailed the use of around 40 components, intensive assembly and high tooling costs, due to the hinge systems being manufactured by stamping, casting or forging. Moreover, hinges made from sheet metal, for example, weigh around 1,500g each, adding considerable weight to every vehicle.
The redevelopment team applied bionic design, or biomimetic engineering, a process of adapting designs from nature that feature complex geometries best implemented in a selective laser melting machine. SLM Solutions systems feature multi-laser options, bio-directional recoating and closed-loop powder handling for safety with increased build speeds for complex and dense metal parts.
Implementing bionic design allowed the LightHinge+ engineers to develop an important additional function of predetermined breaking points on the structure. They were also able to integrate the connections for the gas pressure springs, along with mounts for the windshield wipers. Aside from these enhanced features and improved safety, initial topology optimisation of the design for minimal material requirements enabled a weight saving of 52% compared with the sheet metal construction, enabling the team to meet the specifications and a produce a better part.
The LightHinge+ project, undertaken by working closely with a team from SLM Solutions, provides just one example of the impact of 3D printing on automotive part manufacturing. Australian companies can now access a team of engineers to support individual customer project development, located both in Sydney and Lübeck, Germany.