Self- And Datum-Referenced Form Measurements

摘要

Form or geometry gages are generally divided into two categories depending on what form parameters they are designed to measure. While there is no formal designation to differentiate these two categories-sometimes they are simply referred to as roundness or cylindricity gages-their difference is primarily based on their ability to make self-referenced or datum-referenced measurements. The basic form parameters of roundness, concentricity, circular runout, circular flatness, perpendicularity, plane runout, face runout, circular parallelism and coaxiality are all self-referenced measurements, and they are done with a basic roundness gage. This type of gage stages the workpiece on a precision rotary table and provides a means of positioning the gaging transducer against the part. As the turntable rotates, the gaging transducer senses and measures the devia-tion from the reference circle provided by the spindle.