# A Rule-Based System for Quality Control in Brake Disc Production Lines
## 3 Quality Defect and FMEA Method  
In this study, a brake disc production line consisting of five stations was presented, as shown in Figure 2. The first station is a picking-up station that unloads semi-finished brake discs. Next is the balancing station for cutting imbalanced part and the grinding station for finishing the brake disc surface. Furthermore, to quality assurance of the product, brake discs go to the inspection station for quality specification measurement and individual tracking marking. The last station is the dispatching station, in which all good-quality products are loaded to the final palette. Dispatching stations are not considered in the development of a quality control system, because all quality defects end up being inspected at the inspection station. Figure 3 shows the type of quality defects of brake disc to be inspected in this system, specifically disc thickness variation (DTV), runout, and parallelism. Figure 1: Systematic procedure for carrying out the research. These quality defects are selected based on the number of defects that have occurred on this brake disc production line. However, this type of design is the main specification that must have a brake disc that will lead to the performance system's brake disc. A brief description of each quality defect is given. * DTV: Disc thickness variation is when the brake disc has a difference in thickness across the surface. The design specification of this brake disc is measured at more than 12 points along the circumference, with the management standard being 5 \(\upmu\) or less. This quality defect will lead to uneven wear and cause the two friction surfaces of the disc to no longer be parallel with each other. * Runout: Runout is when the centerline is not parallel and concentric with respect to the hub axis, but instead is tilted with respect to a line perpendicular to the hub axis. The runout tolerance limit of this disc brake design specification is 25 \(\upmu\) or less at a circumstance of 5 mm from the outside diameter. Excessive movement of runout will result in vibration and pulsation in the steering wheel. * Parallelism: Parallelism is the brake disc thickness variation between two surfaces, which are designed to be parallel to one another surface within a certain specification. This quality defect is known as the allowable tolerance coming from DTV. Parallelism is diagnosed by measuring 8 different spots along the surface of the rotor with an outside micrometer and the tolerance limit is 40 \(\upmu\) or less. Considering the selected quality types, this study is driven by the need for a system that enables intelligent acquisition of FMEA data for decision making in offline control processes. Process analysis is implemented by the FMEA method, and quality defects were analyzed more specifically to generate interrelated failures of the production process from each station and on products appearances. Researchers and production teams were both considered for analyzing and determining the risks of potential failure modes for each station. Potential failure effects, potential causes, or mechanisms, and the suggestion of corrective actions for overcoming potential failure modes related to quality defects are also identified as FMEA terminology. FMEA datasheets with a brief description of the  
Figure 3: Three types of quality defect  
Figure 2: Architecture of brake disc production line. terminology and variables for analyzing the brake disc production line are shown in Figure 4. Based on the designed FMEA datasheet, the process function utilizes the features of each station related to finishing manufacturing of brake discs to generate FMEA terminologies. The potential failure mode described the phenomenon in which the process fails to perform its intended function, which will affect the selected quality defects. Then, this terminology is divided into three categories that distinguish between effects, causes, control detection, and recommended actions.