Use of SMA Wire Actuators in a Clamping Device for Small Machine Tools

SMA actuators offer a particularly good relation between size and work capacity. This advantage makes them ideal for miniaturization. In a current research project the use of SMA actuators in a machine tool for micromachining is investigated. The machines currently used in this field show an extensive disproportion between workspace and cross section. This is partly due to the inability to miniaturize the drives and other vital machine parts. Through the use of SMA actuators in downsizing these components, new and innovative machines can be designed. The resulting machine should have a sizeable advantage in cross section and could even be considered for desktop manufacturing. SMA actuators are investigated for their applicability in the feed axis and, in the scope of this paper, the clamping devise used to hold the part in place. The clamping device should be able to lock the part into position for several hours during machining. The generated clamping force should be constant. In addition, a range of part dimensions should be usable with this device. The device should be usable for either parts or mounting plates. This paper examines the development process needed to construct such a small-size, lightweight SMA clamping device. Experimental results from the working prototype are included as well.