Active Fixturing for Mesoscale Manufacturing Systems: Fixel Design Alternatives

This paper presents an investigation of fixel design alternatives for active (dynamic) fixturing to be incorporated into mesoscale manufacturing systems. Using simple compliant mechanisms and components (e.g., monolithic four-bar mechanisms and/or cantilever beams), fixels exhibiting mechanically adjustable stiffness characteristics are achievable. Manually or automating the stiffness adjustments, these fixels provide a functionality for enabling greater control of the dynamic response of the workpiece due to vibrations and variation in contact forces at the tool-workpiece-fixture interface. To quantify the fixel functionality and its dynamic range, this paper presents the theoretical models of the stiffness characteristics expressed as a function of each fixel design’s mechanical variables. Upon establishing a common stiffness range for the different fixel designs, a metric is formed based on the sensitivity of stiffness expressed as a function of slenderness ratio and an operation range, bounded by a maximum possible stiffness value shared by all fixture models. Using this metric, results are generated to delineate the advantages and disadvantages of each design and their potential impact on fixturing and material handling in the creation of micron features on micro and macro parts.