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Advanced gripper development and tests for automated photovoltaic wafer handling

: Giesen, T.; Bürk, E.; Fischmann, C.; Gauchel, W.; Zindl, M.; Verl, A.


Assembly automation 33 (2013), No.4, pp.334-344
ISSN: 0144-5154
Journal Article
Fraunhofer IPA ()
Photovoltaik; material flow; handling; Greifer; Gripper; Bernoulli-Greifer; prototype; wafer; computational fluid dynamics (CFD); wafer processing; design of experiment (DOE); Automatisierung; Materialfluss; Handhaben; Produktentwicklung; Greifervorrichtung; Prototyp; Prüfen

Purpose - The purpose of this paper is to provide a technical review of a new Bernoulli gripper development using computed fluid dynamics (CFD) modeling, and also to outline an appropriate independent testing method for validating and evaluating process capability in terms of automated thin wafer handling. The investigation has been carried out by a collaborative way of Festo and Fraunhofer IPA as a connecting link between applied research and industrial needs.
Design/methodology/approach - Following an introduction, the paper first describes the basic development and fundamental principles of a gripper based on Bernoulli's law. The gripper was dimensioned and designed with the aid of CFD methods. The performance of the hardware was tested using extreme parameter settings while gripping thin, fragile workpieces. The performance of the gripper was tested from the aspects of shortest cycle times, positioning accuracy and air consumption and followed a manufacturer-independent design of experiments. A characterization of the gripping force generated during horizontal and vertical tension tests provides conclusive closed loop validation with regard to the gripper's air flow in the initial CFD model.
Findings - Photovoltaic (PV) grippers are challenging components since the handling objects, 200-120 µmm thin crystalline silicon wafers with an area of 156 × 156 mm, are one of the most fragile parts as far as required handling speeds and cycle times are concerned.
Originality/value - The paper provides a detailed technical review of a CFD application used in the development of a Bernoulli gripper and also describes a method for testing and evaluating PV grippers for industrial scale applications. The article presents the results of a close cooperation regarding an industrial development (Festo AG & Co. KG) and independent applied research (Fraunhofer IPA) for advanced product benchmarking and validation in a relatively young but dynamic and increasingly-automated PV industry.