任何形状都是由三维空间点组成的，所有的几何量测量都可以归结为三维空间点的测量，因此精确地进行空间点坐标的采集，是评定任何几何形状的基础。 三坐标测量机的基本原理是将被测零件放入它允许的测量空间范围内，精确地测出被测零件表面的点在空间三个坐标位置的数值，将这些点的坐标数值经过计算机处理，拟合形成测量元素，如圆、球、圆柱、圆锥、曲面等，经过数学计算的方法得出其形状、位置公差及其他几何量数据。
根据以上原理，三坐标测量仪可定义为一种具有可作三个方向移动的探测器，在三个相互垂直的导轨上移动，此探测器以接触或非接触等方式传送讯号，三个轴的位移测量系统 ( 如光学尺 ) 经数据处理器或计算机等计算出工件的各点坐标(X、Y、Z)及各项能测量的仪器。在进行测量作业时，工人将测量工件固定在特制夹具上，确保工件静止动，测量机的传感器通过三个坐标轴导轨灵活移动，探针系统通过旋转，由 测量软件完成几何尺寸的测量和形状位置公差的评价，最后经SPC导出测量报告和计算评价指标值，从而监控工件精度。
All shapes are composed of points in three-dimensional space, and all geometric measurements can ultimately be reduced to the measurement of three-dimensional spatial points. Therefore, the accurate acquisition of spatial point coordinates forms the foundation for evaluating any geometric form.
The basic principle of a coordinate measuring machine (CMM) is to place the measured part within its permissible measuring space, accurately measure the three-dimensional coordinate values of points on the part’s surface, process these coordinate values via a computer, and fit them into geometric elements such as circles, spheres, cylinders, cones, and curved surfaces. Through mathematical calculations, form and position tolerances as well as other geometric data are then derived.
Based on the above principles, a coordinate measuring instrument can be defined as a measuring instrument equipped with a probe capable of moving in three directions along three mutually perpendicular guideways. The probe transmits signals through contact or non-contact methods, and the displacement measuring systems of the three axes (such as optical scales) compute the coordinates (X, Y, Z) of each point on the workpiece and various measurable parameters via a data processor or computer.
During measurement operations, the operator secures the workpiece on a special fixture to ensure it remains stationary. The sensor of the measuring machine moves flexibly along the three-axis guideways, and the probe system rotates as needed. The measuring software completes the measurement of geometric dimensions and the evaluation of form and position tolerances. Finally, measurement reports and calculated evaluation indicators are exported via SPC to monitor workpiece precision.
