Dimensional metrology plays an important role in the modern manufacturing technology. Accurate machining technology remains the main focus of global industry, where needs to permanent study for the purpose of improving. Coordinate metrology is an important inspection tool of dimension and geometrical surface form for machined work-piece to provide functionality in quality process. Several factors affect the accuracy and quality of manufactured parts when machined using circular pocket cycles on CNC machining centers. Such accuracy depends to a great extent on work-piece material, the cutting conditions; namely spindle speed, feed rate, depth of cut and the structure of the fixed cycle. The accuracy of dimensional and geometrical form plays a vital function on the required tolerance and fit of manufactured parts to be assembled.This paper studies the influence of those parameters on the accuracy and quality of milled pocket diameter with its roundness. Several specimens made of aluminum, copper and steel metals were pocket milled on a CNC using different cutting conditions. CMM was used to assess the errors in diameter and roundness measurements of machined parts. In despite of scientific advances in machining technology, however there are still clear deviations in the measurement results according to choice of the cutting condition, especially when change the type of work-piece material. Monitoring suitable validiation method for a typical manufacturing machining is achieved accurately. Moreover, expanded uncertainty in measurement has been estimated using statistical repeatability analysis and most effective experimental parameters.