A shape memory alloy based tool clamping device

The traditional collet-chuck mechanism for tool clamping is a significant source of errors in spindles due to stack-up tolerances. This, in turn, adversely affects the toolʹs error motions particularly in demanding micro-cutting operations performed with ultra-high-speed miniaturized spindles. Hence, novel thought for miniature tool clamping is needed to minimize tool run-out and error motions in order to meet the necessary cutting speeds and accuracy requirements. In this paper a couple of Shape Memory Alloy (SMA) based solutions for the clamping of miniature tools will be explored. For clamp actuation the so-called Two-Way Shape Memory Effect (TWSME) property of NiTi SMAs will be exploited. The basic principles, design requirements, analysis and physical realization of these devices will be discussed. It will be shown through experimental verification tests that clamping forces in excess of tens of Newtons are possible, confirming thus the feasibility of the proposed solutions.