Evaluation of geometrical parameters of workpieces in serial production under harsh environmental conditions

Thermal expansion is a property of materials, which was discovered a long time ago, comprehensively studied and explained. However, the consideration of the effect in the field of metrology if often not trivial. It is accepted state of technology to integrate measurement processes into a production process with the aim of establishing quality control loops. That make the production process robust against a variety of disturbing influence factors. According to existing standards geometrical measurements should be performed under controlled environmental conditions. Particularly the temperatures of the measuring instrument, the workpiece and the air must be adjusted to 20 °C (normal temperature). In observance of the above stated requirement causes errors due to of thermal expansion of the materials. Investment in air-conditioning equipment may turn out to be quite expensive, especially for companies in developing countries with tropical climate. High-end measuring instruments with thermal compensation equipment and thermal enclosures (the equipment allowing to isolate a measuring instrument from the surrounding area to maintain constant temperature conditions of the instrument) exist, but they are not always affordable, too. The aim of this research project is to develop and investigate an alternative method how to perform measurements under non-normal conditions and correct the results afterwards without having knowledge about the construction details of the measuring instrument nor current thermal conditions of any object, involved in the measurements.