A contribution for increasing workpiece location accuracy in a 3-2-1 fixture system

The 3-2-1 fixture design principle is the most used method to locate prismatic workpieces. To further increase location accuracy, the influence of friction and contact stiffness between workpiece and fixture parts should be minimized. This can be achieved by decreasing the structural stiffness of the locators in the tangential direction to the contact. Hence, based on flexure hinges, locators with two different stiffness values are investigated. To analyze the influence of locator stiffness, a special experimental setup is developed to study two locators positioned in the secondary plane of the 3-2-1 fixture. Experiments are carried out to compare the locators with flexure hinges to a rigid one. The displacement and rotation of the workpiece are investigated as a function of the clamping force. The experimental results show that the reduction in the tangential stiffness can improve the position and orientation accuracy of workpieces.