## 4 Application of the Concepts: Design of an In-Line Measuring Machine
### Analysis of Current Gauging Process and Target Specifications  
To prevent defective products from reaching the customer, manufacturers strive for zero-defect-production. This is particularly true for the automobile industry [43], in which part traceability [44] has become an essential tool to analyze and predict part failure. In practice, manufacturers are moving towards verifying all critical specifications in every single part produced. Conventional inspection methods, which combine in-line gauging  
Figure 3: Provide Connectivity function block. Specific actions are performed in this function, as data flows in either direction. procedures with off-line metrology systems to verify part compliance with specifications and identify sources of error [23] are not designed for this new approach, as only samples of parts are fully verified before they are released. In response to these changing needs, a new paradigm for in-line inspection system design, in which all critical specs of all parts are measured, is emerging. This particular case deals with the design of a machine in a casting operation. Figure 4 presents a schematic of the process that is followed to produce and inspect an aluminum die-cast part. After the casting process, a robotic arm takes the workpiece from the die casting die to a cooling water system and then to a punch press where excess material is removed. The part is then delivered to a gauging station, where a flatness test is performed. The test consists of measuring the height of approximately 20 points with linear variable displacement transducers (LVDT). Measurements are reported on a monitor screen. No provisions are made to store or transfer the data from the measurements. The environment around the measuring station is typical of die casting operations: ambient temperatures can vary between 18 \({}^{\circ}\)C and 38 \({}^{\circ}\)C depending on the time of the day and season of the year. Steam released during the casting and quenching processes produce ambient humidity, and the punching operation produces noise, shock, and vibrations. The plant has several similar cells, which contribute to the overall conditions. In general, in-line gauging systems in the automobile industry are built for robustness and speed. In this case, the pace of the part measuring process is given by the casting operation, which takes about one minute. Measurements need to be made in about 20 to 25 s to allow the operator to try to make corrections to the part if needed. As seen in Figure 5, the position of each LVDT is fixed, and therefore the gauging system can only be used for the specific part for which it was designed. The probes are covered and therefore they are well isolated from accidental impacts. Figure 4: Workpiece process. The robot takes the part from the die casting machine (1) and submerges it in a water tank (2). The robot then inserts the part in a trim die, where excess material is removed. The workpiece is then delivered to a measuring station to check the flatness of the surface of the casting. The main advantages of the current measuring station are reliability, robustness, and simplicity of operation. On the other hand, the gaging inspection system's main weaknesses are its lack of flexibility, the tendency of the LVDT to catch debris from the part or the environment, and the lack of system information for the integration to I4.0. The intention of the new design was to maintain the advantages of the current system, while adding flexibility and Connectivity to the Cloud. The use of permanently fixed sensors posed the main obstacle to achieve flexibility. The use of a moving probe allows the possibility to reconfigure the measuring plan. However, given that the measuring cycle needs to be completed in less than 25 s, speed becomes an important issue. As stated by [45], the use of contact probes limits the speed with which measurements can be made. Therefore, a laser probe was proposed for the application.