Machine tool errors caused by optical linear encoders

Position measurement in machine tools is usually carried out through rotary or linear encoders. Quite often, it is considered that part dimensional errors are only due to direct strain, thermal or vibration effects in the machine tool structure. There is, however, another important source of error: the encoder itself. This paper is intended to recognize, classify and determine the value of the different kinds of error in optical linear encoders: strain and displacement errors, thermal errors and errors caused by vibrations. The error identification will also permit a better understanding of some of the limitations that appear in the use of these devices.