Adaptive Slicing and Process Optimization for Direct Metal Deposition to Fabricate Exhaust Manifolds

Abstract

Direct metal deposition is an additive technology that has the potential to fabricate large parts in multiple buildup directions. Especially curved, thin-walled geometries such as exhaust manifolds are a promising use case: In theory, direct metal deposition allows nearly arbitrary shapes. Internal surfaces that are not accessible with the final part could be inspected and machined in a stepwise buildup process. However, the successful production of such parts requires suitable algorithms for five-axis tool path planning as well as for the optimization of the parameters for the specific process. Herein, an adaptive slicing algorithm is presented that aligns the direction of each layer for minimized overhangs and creates the tool path under consideration of the process capabilities and limits. By a variation of the scan speed, the deposited powder per length and therefore the layer height can be modified continuously. A model-based feedforward control of the laser power accounts for the varying thermal conduction in thin walls. These approaches are integrated in a fully automated CAM software that generates a suitable tool path with locally adapted parameters. The fabrication of an exemplary exhaust manifold shows that the software reduces the manual preparation effort and enables a flexible additive manufacturing process.