Among all the operations involved in the micromanufacturing of microproducts and complex microelectromechanical systems, microassemby is the most critical one. According to the current industrial context, contact grippers, such as tweezers and vacuum based are mostly used. The main drawback related to contact tools is the elevated risk of damaging the component during handling. Furthermore, the present grippers are required just to grasp and handle the product, whereas alignment and releasing tasks are frequently carried out by external systems. In this thesis, capillary effect has been exploited as contactless gripping principle. When the characteristic length of the handled component is smaller than the capillary length of the working fluid, gravity becomes negligible in comparison with the capillary forces. The objective of the work is to design and manufacture a fully 3D printed capillary microgripper for pick and place applications. Besides the picking and handling operations, the tool is designed to align and release by itself the handled 1005 SMD component. The re-picking task and the amount of liquid left on the object after releasing are investigated as well. The manufacturing process is based on two-photon polymerization and stereolithography techniques. The picking head is printed with Nanoscribe Photonic Professional GT on an Autodesk Ember printed component, combining the sub-micron resolution of the first one with the handleability of the second one. Moreover, a PDMS based replication technique is proposed for large scale fabrication. Finally, the pick and place routine has been successfully demonstrated: the gripper is proved to be able to pick, align and release the component without external help. Furthermore, the re-picking task has been tested as well, covering all the operations performed in the industry.
Tra tutte le operazioni coinvolte nella produzione di microparti e MEMS ibridi, l'assemblaggio è la più critica. Nell'attuale contesto industriale, vengono utilizzati principalmente gripper di contatto o suzione. Lo svantaggio principale legato a questi strumenti è l'elevato rischio di danneggiamento del componente durante la manipolazione. Questi gripper sono utilizzati per sollevare e movimentare il prodotto, mentre le attività di allineamento e rilascio sono spesso eseguite da sistemi esterni. In questa tesi, l'effetto capillare è stato sfruttato come principio di gripping non invasivo: quando la lunghezza caratteristica del componente in questione è inferiore alla lunghezza capillare del fluido di lavoro, la gravità diventa trascurabile rispetto alle forze capillari. L'obiettivo del lavoro è progettare e produrre un microgripper capillare completamente stampato in 3D per applicazioni di pick and place. Oltre alle operazioni di prelievo e movimentazione, lo strumento è progettato per allineare e rilasciare il componente SMD 1005. L'operazione di ri-presa e la quantità di liquido rimasto sull'oggetto dopo il rilascio sono state altrettanto analizzate. Il processo di produzione si basa sulla polimerizzazione a due fotoni e la stereolitografia. La punta da presa è stampata usando la stampante Nanoscribe Photonic Professional GT su un componente stampato con la tecnologia Autodesk Ember, combinando la risoluzione sub-micrometrica della prima con le dimensioni millimetriche del secondo. Una tecnica di replica basata sul PDMS è proposta per la fabbricazione su larga scala. La procedura di pick and place è stata effettuata con successo: è stato dimostrato che il gripper è in grado di sollevare, allineare e rilasciare il componente senza aiuti esterni. Inoltre, anche l'attività di re-picking è stata testata, coprendo tutte le operazioni svolte nel settore.
Design and manufacturing of a capillary microgripper
CAVAIANI, MARCO
2016/2017
Abstract
Among all the operations involved in the micromanufacturing of microproducts and complex microelectromechanical systems, microassemby is the most critical one. According to the current industrial context, contact grippers, such as tweezers and vacuum based are mostly used. The main drawback related to contact tools is the elevated risk of damaging the component during handling. Furthermore, the present grippers are required just to grasp and handle the product, whereas alignment and releasing tasks are frequently carried out by external systems. In this thesis, capillary effect has been exploited as contactless gripping principle. When the characteristic length of the handled component is smaller than the capillary length of the working fluid, gravity becomes negligible in comparison with the capillary forces. The objective of the work is to design and manufacture a fully 3D printed capillary microgripper for pick and place applications. Besides the picking and handling operations, the tool is designed to align and release by itself the handled 1005 SMD component. The re-picking task and the amount of liquid left on the object after releasing are investigated as well. The manufacturing process is based on two-photon polymerization and stereolithography techniques. The picking head is printed with Nanoscribe Photonic Professional GT on an Autodesk Ember printed component, combining the sub-micron resolution of the first one with the handleability of the second one. Moreover, a PDMS based replication technique is proposed for large scale fabrication. Finally, the pick and place routine has been successfully demonstrated: the gripper is proved to be able to pick, align and release the component without external help. Furthermore, the re-picking task has been tested as well, covering all the operations performed in the industry.| File | Dimensione | Formato | |
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2017_12_Cavaiani.pdf
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https://hdl.handle.net/10589/137883