Feasibility and uncertainty evaluation of sequential hybrid manufacturing using optical coordinate metrology

Hybrid manufacturing has been suggested as a solution to global manufacturing challenges including stock availability, manufacturing costs, and difficulty in production of complex parts. However, feasibility and validation of hybrid manufacturing remain open research opportunities.

This research evaluates measurement uncertainty for optical coordinate metrology (OCM) within a sequential hybrid manufacturing (SHM) framework where a primary manufacturing process, a part geometry measurement, and a secondary manufacturing process are performed sequentially on optionally separate machine tools. In this work, an additively manufactured preform is produced, the part geometry is measured using structured light optical coordinate metrology, and the final geometry is obtained using subtractive manufacturing. Quality parameters for four low to high cost OCM 3D scanning systems are found using a performance evaluation based on current ISO and VDI/VDE standards. Uncertainty of a fiducial sphere's center position is defined using the selected OCM system. This uncertainty is then propagated into the uncertainty of the coordinate system position and orientation for a coordinate system defined by three sphere centers using Monte Carlo simulation. The simulation results are validated with experimental testing. An additional function is implemented into the simulation to estimate the required overbuild to account for the coordinate system positional and rotational uncertainty. A case study with wire arc additively manufactured preforms is provided. Combined, this work represents a step towards validation, traceability, and feasibility of sequential hybrid manufacturing.