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Measuring Error of CMM (I)

Dec 29, 2016

At present, coordinate measuring machine(CMM) is widely used in the industry, it is a kind of general-purpose measurement equipment with high precision, high efficiency, it is the quality assurance tools of mechanical processing, mold manufacturing, automobile manufacturing, aerospace and other industries. Therefore, it is important to use CMM in the production.

1. Mechanical Error

CMM itself exists errors because of parts machining, calibrating and other factors. Usually according to the geometric parameters of the error in all degrees, divide errors into three position, 6 straightness, 9 Angle error and 3 squareness. Totally 21 items of parameter error.

2. Measuring Method Error

CMM is used in size error measurement of parts and components, form and position error measurement, especially it has high accuracy, high efficiency and large measuring range in form error measurement.  And there are many sorts of methods to measure form &position errors, GB1958-80<The shape and position tolerance test regulations> specified there are five error detection principle: compared with the ideal element principles; the principle of measuring the coordinates; the principle of measuring characteristic parameters of runout. And it also lists more than 100 kinds of measuring methods. If we cannot use the right detection principle when measuring form &position errors, it will cause measurement error. Therefore, people who engaged in the operating of the CMM must be familiar with measuring method, especially the method to detect form& position errors.

3. Human Error

Common reason of human error: points record is taken under certain load conditions. Human error is occurred when manual collecting points, the measurement speed of each person is different, which lead to human error. The other cause of human error is that it is difficult to collect points in its direction when measuring elements. Or what we often say that the actual measurement point and the theory of cosine error of measurement point.

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