Meaning
Three dimensional error measured at the tool tip relative to the intended coordinate system. Unlike simple axial error, spatial coordinate deviation accounts for the combined effects of all moving axes and their squareness to each other.
Volumetric Inaccuracy
Geometric flaws such as roll, pitch and yaw in the individual axes contribute to the total error. When the spatial coordinate deviation is mapped, it reveals regions of the machine volume that are more accurate than others. Manufacturers use this data to determine the optimal placement for the most critical workpiece features.
Path Correction
Advanced controllers can use a volumetric map to adjust the motion of the axes in real time. This adjustment reduces the spatial coordinate deviation by compensating for the known mechanical imperfections of the machine. The result is a tool path that more closely follows the digital model, even on large and complex parts that span the full working envelope of the machine tool.
Calibration Procedure
Laser tracers or ball bars are used to measure the deviation at numerous points in space. Measuring the spatial coordinate deviation is a time consuming process but it provides the most complete picture of machine performance. This thorough evaluation is required for the production of components with complex curved surfaces.
