Abstract
Fixtures are used to fixate, position and support workpieces and represent a crucial tool in manufacturing. Their performance determines the result of the whole manufacturing process of a product. There is a vast amount of research done on automatic fixture layout synthesis and optimisation and fixture design verification. Most of this work considers fixture mechanics to be static and the fixture elements to be passive. However, a new generation of fixtures has emerged that has actuated fixture elements for active control of the part–fixture system during manufacturing operations to increase the end product quality. This paper analyses the latest studies in the field of active fixture design and its relationship with flexible and reconfigurable fixturing systems. First, a brief introduction is given on the importance of research of fixturing systems. Secondly, the basics of workholding and fixture design are visited, after which the state-of-the-art in active fixturing and related concepts is presented. Fourthly, part–fixture dynamics and design strategies which take these into account are discussed. Fifthly, the control strategies used in active fixturing systems are examined. Finally, some final conclusions and prospective future research directions are presented.
Highlights
Workholding devices and systems, such as fixtures, are of paramount importance within a manufacturing environment
Sensor-based fixture design is a fixturing strategy where vision and sensor systems are utilised to ensure that the part is located correctly in the fixture
Another approach has been taken by Culpepper et al (2005), who developed an eccentric ball-shaft-based positioning-table fixture concept, where the balls are actuated by ball-screw actuators to increase the accuracy of part positioning
Summary
Workholding devices and systems, such as fixtures, are of paramount importance within a manufacturing environment. Geometrical variations in the features of the fixture reduce the locating accuracy of the workpiece relative to the global coordinate frame of the manufacturing process. This can result in the production of out-of-tolerance parts. Developments relevant to active fixturing systems in the following areas, which are only marginally and dispersedly touched upon in the other review papers and standard textbooks, are discussed: fixture design concepts, the effect of the dynamic nature of the manufacturing forces on the part-fixture system, especially regarding active fixtures, and active fixture control strategies.
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