Actual manufacturing machines must have a repeatable and accurate behavior. Unfortunately, according to a CIRP evaluation, more than 50% of the machining errors even in the case of modern machine tools are due to the thermal phenomena. The optimization of the thermal behavior of machine tools is a very important part of a unitary metrology concept, which must take into account all factors, proportional with their importance. The author has carried out for the first time in Romania, a thermographical study of machine tools. The obtained improvement contributed to a better quality and a higher precision of Romanian machine tools and also to a better technological organization inside the factory. There were some first steps (in the years '70 -'80) of the quality management in Romania, according to the international standards, and advanced metrology concepts. The paper presents some of the results obtained at the Technical University of Cluj-Napoca, Romania. Other tests were carried out at the University of Stuttgart, Germany.