The role of a turbocharger is simple : It uses an engine’s exhaust to power a centrifugal compressor, pressurizing the intake air that will be mixed with fuel in an engine’s cylinders.
Greater pressure means higher density, and by increasing the mass of air entering the cylinders’ combustion chamber, the turbocharger augments the engine power output. The gas expansion and air compression stages have necessitated numerous continuous improvements in the decades since the turbocharger’s invention, and today’s high-performance versions have functional geometries designed around thermal isolation and optimal flow.
Image: Final 3D printed turbocharger housing (with 3D printed impeller)
In motorsports, overcoming engineering challenges usually require iterative design and rigorous testing of new components, but with investment casting, every new component means a new mold. Because many manufacturers depend on their suppliers for castings, the lead times quickly add up, and unlike major automakers, few racing teams have the luxury of a worldwide network of manufacturing facilities. Even when manufacturers use alternatives for R&D, such as wax-printed models, meeting deadlines often requires going from product design to production as quickly as possible – and going between wax-printed and wax-injected models generally doesn’t work.
Finding an integrated solution
Of course, casting is only one part of an entire challenging turbocharger workflow. Tough turbocharger materials like Inconel and other superalloys make finishing parts a tough milling application – and machining can only occur after reference points on the cast part have been established, a time-consuming operation in and of itself if not carefully managed throughout the entire part-production cycle.
Major automakers and other global manufacturers excel at this kind of process management due to the resources they can devote to the problem. For smaller manufacturers, including most working in the motorsports industry, it can be difficult to bring a diverse group of suppliers and technology providers together into a single, effective workflow. Integrating an entirely new technology is an even larger challenge – one with enough risks that many manufacturers will avoid by sticking with what they know.
Image: Conventional machining process of high-temperature resistant material are complex due to high cutting forces, low material removal rates and high tool wear.
Software and design
Thanks to 3DXpert™ and Cimatron™, the entire production process can be managed within a single software ecosystem that handles everything from part design, build preparation and CNC preparation to in-process inspection and part validation.
Additive and subtractive manufacturing
The DMP Flex 350 metal AM machine builds parts quickly, while the CUT AM 500 removes them from the build plates through an innovative horizontal EDM process and the MILL E 700 U high-performance milling machine performs post-build machining on a full 5-axis platform ideal for complex parts.
System 3R tooling optimized for AM processes – the Delphin TableTop Chuck, AMCarrier and BuildPal – can be used to preserve reference points and angular alignment at the same time it enables palletized automation throughout the workflow.
3DXpert™ and Cimatron™
With metal AM, the technology only drives the design insofar as parts usually need additional support structures and stock considerations for post-processing. For the most part, AM allows manufacturers to focus on the functionality of the part. Without the limitations of other processes, AM gives engineers the tools to push their designs even closer toward theoretical optimization – and consolidate complex assemblies into a single part.
Image: Part orientation and support generation with 3DXpert™
3DXpert™ also offers a range of tools aimed at simplifying part programming for metal AM. There are a number of AM-specific structures, geometries and print strategies that the software can apply automatically. In Cimatron™, this feature even provides advanced milling strategies during post-processing “in its design”, such as the trochoidal milling required to remove the tough Inconel supports that were used to hold up the part during and after the metal AM process.
Image: Simulation stages with 3DXpert™
Indeed, the software also helps manufacturers avoid risk with robust simulation capabilities. With parts such as the turbocharger, where expensive materials and a long build cycle create a high-value workpiece, getting the real-world process right on the first attempt is critical. Using 3DXpert™, multiple build iterations can be simulated to perfect build processes. As a result, potential issues like stress accumulation or elevated displacement can be addressed long before 3D printing begins.
Image: AM supports are considered for post-processing operations thanks to data exchange between 3DXpert™ and Cimatron™
An additive workflow will naturally be built around its AM system, and GF Machining Solutions offers industry-leading selective laser sintering technology through its Direct Metal Printing (DMP) series of machines. A versatile, thoroughly proven AM solution designed for the utmost in simplicity and speed, the DMP Flex 350 acts as the center of the workflow for the turbocharger demonstration. System 3R tooling provides the connections between other machines and the DMP Flex 350 to ensure full additive scalability and easy access to automation.
Part separation and post-build machining
Following a quick de-powdering process, post-machining can begin. Typically, an additional step is required – most additive processes require operators to remove AM support structures manually. However, thanks to the unified software ecosystem (3DXpert™ & Cimatron™) and palletized reference preservation, this step can be handled automatically as part of post-processing. Even without robotic assistance to handle pallets, as part of post-processing, as the BuildPal units themselves maintain the physical data chain across the entire process.
For parts such as a F1 turbocharger that includes functional elements that must be precisely refinished, keeping the part on the BuildPal maintains the same coordinate system for machining reference surfaces and holes with the highest possible precision. These same references can be used when re-clamping a difficult-to-align part such as a turbocharger for post-separation machining. For part separation, GF Machining Solutions’ additive workflow uses the AgieCharmilles CUT AM 500, an innovative horizontal wire EDM machine, while all functional surfaces plus the pre and post-separation processing steps are carried out with a Mikron MILL E 700 U.
MILL E 700 U
The MILL E 700 U is a high-value, efficient solution for 5-axis simultaneous machining. Large guideways, a double-side-supported direct drive rotary table and optimal chip removal rates allow this machine to easily handle a wide range of milling applications. These features, as well as its capacity for advanced milling strategies through Cimatron™ software and its flexible, automation-ready design make it an ideal machine for demanding AM parts’ post-processing needs.
CUT AM 500
Designed around a unique tilting table that reorients AM parts for a horizontal-wire EDM process, the AgieCharmilles CUT AM 500 is the fastest, most effective method for AM part separation. The EDM-level surface quality and small-diameter molybdenum wire allow for high-quality surface finishes. The machine’s layout is also specifically designed for the integration of the AMCarrier automation-ready clamping system for the lowest risk of part damage.