The ergonomic principles integration into manufacturing engineering processes design and development is becoming a common practice in companies. In this regard muscle-skeletal injuries have an important impact in workplaces. The evaluation and measurement of risk factors is an important step towards workplace Excellency. In this work they are described the evaluation methods most commonly used, and it is showed the application of RULA "Rapid Upper Limb Assessment" and REBA "Rapid Entire Body Assessment" methods in a metal sector company with the help of virtual simulation tool in which arc integrated both methods via external programming. The entire production process is evaluated and improvements suggested in order to eliminate those ergonomic risks and to improve the production system. It is the objective of this paper to show the advantages of using these tools, as well as to implement, an adequate observation method in this field.