Machining performance evaluation for B-Type five-axis machine tool

Since a five-axis machine tool has linear and rotary axes that are connected in series, motion errors of each axis and its assembly error are accumulated in the positioning error of a tool relative to a workpiece. There are many devices reported in the literature on the identification of kinematic errors based on the measurement of the motion error. Although it is important to evaluate kinematic error using non-cutting measurement, users concern more the evaluation of machine's accuracy when it performs the actual machining. The National Aerospace Standard (NAS) 979 presents five-axis machining test of a cone frustum on five-axis machine tool with a universal spindle. Several conditions for tilting rotary table type have not been defined in this standard. In order to improve the accuracy of five-axis machine tool, it is important to develop a methodology to estimate it. This paper proposes a machining test for a B-Type (tilting rotary table type) five-axis machine tool to evaluate its performance. The workpiece consists of 10 machining features. These features include the multi-axis simultaneous machining patterns and the positioning machining patterns. The setup of workpiece is away from the rotational centre of C-axis. The flat end mill cutters are applied in each machining feature. Geometric errors of finished workpiece are measured using a coordinate measuring machine (CMM). Experimental results demonstrate that the influence of kinematic errors can be observed based on the error profiles of finished workpiece.