Research On Device And Process Of Multi-material Seterolithography

Compared with traditional manufacturing technologies,3D printing requires little process planning and has a unique feature naming “what you see is what you get”.It is very capable of manufacturing complex 3D structures and is suitable for individual or small-batch production.The additive nature of 3D printing enables on-demand deposition of different materials in different coordin ates in a single part.However,current 3D printing technologies has many limitations in multi-material fabrication.Combination of materials of different electrical,magnetic,thermal and mechanical properties can achieve 3D printing of functional parts.Multi-material stereolithography had proved its value in applications such as metamaterials,tissue engineering and soft robotics.But research of multi-material stereolithography(MMSL)is not thorough enough.Current device can only print two materials i nto a single part.Lacking leveling ability and method,large error in material alignment results in poor accuracy both within layer and in z direction.MMSL's device and process are studied to improve MMSL's fabrication capability.This study focuses on device design,process control and fabrication experiments.Bottom-up MMSL was selected for manufacturing interlocking multi-material structures with hierarchical complexity.Device's overall layout and mechanical structures were designed,including separate leveling structures for each resin vat.The angular resolution leveling structure was ca lculated and the influence of refraction on fabrication accuracy was analyzed.A process planning algorithm was proposed for bottom-up MMSL to reduce material changeover.Mathematical model of projection stereolithography was established.A image morphological compensation algorithm was proposed for reducing printing error in xy plane.A selective image dilation algorithm was proposed to manipulate overlaying area of multi-material boundaries.Experiments were performed to verify above-mentioned algorithms.Three different resin was selected and their curing parameters were determined via designed experiments.Printing error was measured with test model carrying a serie s of standard features with proportional dimensions.Error was compensated via image morphological compensation algorithm and retested.The effectiveness of this algorithm was verified.Manipulation of multi-material boundaries' overlay was achieved via selective image dilation algorithm without affecting dimensional accuracy of single material boundary.Finally,a complicated interlocking multi-material part was designed and manufactured,verified the device's capability of manufacturing interlocking multi-material parts.A 3-material MMSL device and process of 43.75?m resolution,35×56×40mm3 fabrication volume,100?m layer thickness and less than 50?m of misalignment error was achieved.