Festo gets to grips with laser sintering
02 April 2012
Festo has used additive manufacturing to produce its latest innovation - a bionic gripper. Fast and economical batch production of the complex components that go to make this product is achieved using a laser sintering machine supplied by EOS.
The advantages of additive manufacturing (AM) over conventional manufacturing practices are many. Thanks to the design freedom of this layer-by-layer technique, the number of individual parts can be reduced, making assembly less costly. Moreover, no injection mould tools are needed, meaning further time and cost savings.
Festo has been gathering experience with AM since 1995. What began with concept models and functional prototypes has now developed into the manufacture of several thousands of parts per year, and the development of its ‘bionic handling assistant’ is no exception.
Unlike conventional industrial robots, this pneumatically controlled gripper arm is very safe; in the event of a collision the system yields immediately. The design allows for smooth movement, with eleven degrees of freedom and an unparalleled weight/payload ratio.
Products derived from nature are often of complex design. The flexible bionic handling assistant is based on the elephant's trunk and consists of three elements for spatial movement. At the end is a 'hand' – essentially an adaptive gripper, modelled on a fish fin. Klaus Muller-Lohmeier, who heads up advanced prototyping technology at Festo, takes up the story:
"The gripper's functionality and structure, incorporating components of complex geometry, makes it impossible to produce the product by any means other than AM. Just four components produced in an EOS Formiga P100 laser sintering machine are sufficient to make a complete bionic handling assistant.
"Thanks to the design freedom that laser-sintering gives us, we can manufacture movable, flexible but also specifically rigid shapes, just as they occur in nature. Our designers can operate independently of the restrictions of conventional manufacturing techniques and concentrate fully on the implementation of the natural principles they have analysed.
"We are using laser-sintering more and more for projects in which limited annual quantities of a complex part are required. In these cases, the process is a real alternative to existing, often tool-based methods."
Of particular note is the fact that the gripper elements have their final functionality immediately after laser-sintering, without need for post-assembly. Moreover, the adaptive gripper is some 80 per cent lighter than conventional metal grippers – and there is no loss of mechanical performance. Studies have shown that the gripper elements can withstand more than five million bending cycles.
In a separate customer project, Festo manufactured 12,000 components using laser-sintering as an alternative technology, saving 40 per cent of the unit cost compared with injection moulding. All parts were finished within one week in just four build cycles, whereas conventional production would have taken two months. Festo’s customer was able to take its product to market much faster, as a result.
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