## 3 Case Study. The Applied Evaluation Processes
### Phase 2: Human-Machine System  
A human-machine system for the machine tool was designed in this phase. The procedure was as follows:  
Figure 3: The production system of the human–machine system. Figure 2: The production system with an open system approach. Data collection. To obtain uniform and consistent information, first, a standardization of the terminology used to identify the failures that occurred and the assignment of their causes and sub-causes were performed using the following materials and methodology:  
1. An awareness interview was conducted with operators, technicians, designers, programmers, and managers to establish a diagnosis that facilitated the survey's design. 2. The survey was designed and applied to identify the terminology used in the presence of failures, when they occurred in the area, the causes and sub-causes that originated them, and the places where they occurred. 3. Based on the standardized terminology and the survey's results, a relationship matrix was created. Based on the name of the failure and the assigned causes and sub-causes in the different areas, the used terminology was standardized and used to create a catalog of visual aids. 4. A database was designed in excel that records the failures, causes, and sub-causes. They were recorded according to their (standardized) name, production date, part number, and standardized type of failure. Classification and analysis of data. Once the information was collected in the database and it was standardized, for the analysis of the failures, a classification was performed to identify the causes, classify them, determine the place where they were detected, and determine the sub-causes of the failure. Each failure's classification was carried out with the information from the three participating machining workshops. To carry out this activity, the participation of production, quality, and engineering personnel from the three machine shops considered was required. The procedure followed is described below. Detection of failures that occurred in the machine tool area. Detection of the failures in the machine tool area in the three machine shops was conducted in order to use only standardized failures. Some examples of these failures are great height, pores, large groove dimension, groove out of tolerance, bad grips, and chopped materials. Identification of causes and sub-causes of failures and the places where the failures occurred. The failures that occurred in the machining area were analyzed based on their causes, sub-causes, and where they occurred using the root-cause analysis (RCA) [28; 29; 30; 31]. The sub-causes of failure were listed and classified by groups or clusters and the place where the failure occurred. As a result, the six sub-causes used in this research are called components and the six places where the failures occurred are called subsystems. With them, a proper and adequate classification was obtained to develop a relationship matrix. Matrix of component-subsystem relationships. Using the classification of faults through the cluster technique and root-cause analysis (RCA), a relationship matrix between components and subsystems was constructed, identifying the component and subsystem relationship. This matrix is presented in Table 3, showing that Admission Profile and Institutional Conditions/Attitude are present in every one of the six subsystems. Maintenance/Setup, Supplier, Calibration, and Information/Communication only influenced some blocks.