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Hybrid Fused Filament Fabrication with In-Process Machining
Hybrid Fused Filament Fabrication with In-Process Machining
Fused filament fabrication (FFF) is the most widely used additive manufacturing process thanks to its low cost and easy setup, but it is limited by low accuracy, poor surface finish, slow build time, and inferior anisotropic mechanical properties. In this study, we conduct experimental studies to investigate the integration of in-process machining with FFF using PLA filaments on a commercial multi-head printer setup. A hybrid FFF with in-process machining test platform with process monitoring capabilities was developed. Tests were then conducted to evaluate the FFF-machining process parameters and integration strategies. The experimental platform development process identified that spindle rigidity and newly printed filament temperature control (e.g., quick cooling with compressed air nozzle) were two key considerations for a high-quality machined surface.
Experimental testbed for hybrid manufacturing process:
Proof-of-concept demonstrations:
Machined surface temperature sensor for data-based hard turning tooling management
Machined surface temperature sensor for data-based hard turning tooling management
The tool-foil thermocouple forms a thermometric junction between the cutting tool and embedded metal foil. As the first technology to provide real-time on-site measurements of the machined surface temperature in hard turning without inverse heat transfer modelling, it scanned the steady-state machined surface temperature at multiple segments, enabling correlation between cutting conditions, tool wear, and machined surface temperature for better product quality and data-based tooling management decisions.
Experimental setup
Tool-foil concept
Tool-foil thermocouple calibration
Cylindricity error analysis to move beyond trial and error and reduce ramp-up time
Cylindricity error analysis to move beyond trial and error and reduce ramp-up time
To identify error sources for cylindricity in finish cylinder boring process, data from multiple sources (design, process, and inspection) needed to be unified and analyzed. This study established a comprehensive cylindricity error prediction and data processing methodology in finish cylinder boring with pioneering inclusion of spindle error data as a dominant factor. Such methodology is implemented at Ford for shortening the ramp-up time of modified engine block designs.
Finish boring experimental setup
CMM scan result
Error Sources Analyzed:
Thermal expansion
Cutting force
Clamping force
Spindle error
Data Unification and Error Source Identification:
Harmonic analysis of CMM data
Cylindricity error source identification result
Thermal modelling of friction stir extrusion process
Thermal modelling of friction stir extrusion process
Friction stir extrusion process could extrude lightweight metallic tubing that enhances mechanical and metallurgical properties with respect to traditionally extruded tubular products, critical for lightweight material structures like automotive frames and marine hear exchanger tubes. In a collaborative project led by Lockheed Martin under Manufacturing USA Institute LIFT, pioneering work on experimental temperature monitoring and finite element thermal modelling of the newly developed friction stir extrusion process were conducted.
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