COMPUTER AIDED QUALITY CONTROL

Guided by the quality plan, the computer-aided quality inspection and quality data collection receive quality data during different phases. The phases include purchased-mateiial and part-quality inspection, part-production-quality data collection, and final-assembly quality inspection. The methods and techniques used in quality inspection and data collection are discussed in special books on quality control (Taguchi et al. 1990). 

Figure 2. Flow diagram for control of incoming materials at a supplier to the automotive industry [9]. (CAQ = computer-aided quality) (With permission from Kunststoffe.)...

The correct interpretation of measured process data is essential for the satisfactory execution of many computer-aided, intelligent decision support systems that modern processing plants require. In supervisory control, detection and diagnosis of faults, adaptive control, product quality control, and recovery from large operational deviations, determining the mapping from process trends to operational conditions is the pivotal task. Plant operators skilled in the extraction of real-time patterns of process data and the identification of distinguishing features in process trends, can form a mental model on the operational status and its anticipated evolution in time. 

In addition, the measurements are rapid and simple, and are now even used in 100% inspection for quality control of multiple-layer semiconductors. An example is shown in Figure 1.6. This is a GaAs substrate with a ternary layer and a thin cap. The mismatch between the layer and the substrate is obtained immediately from the separation between the peaks, and more subtle details may be interpreted with the aid of computer simulation of the rocking curve. This curve can be obtained in a matter of minutes. Routine analysis of such curves gives the composition of ternary epilayers, periods of superlattices and thicknesses of layers, whilst more advanced analysis can give a complete strain and composition profile as a lunction of depth. 

The basic design of the gas chromatograph can be fitted with a range of specific injectors, columns and detectors to optimize the separation of components and aid their identification. Recent developments in computer control, the use of robotic autosamplers and the trend to couple instruments together for sequential procedures have lead to increased automation for routine analytical tasks performed by GCs in research, factory and quality control environments. 

The computer-aid qu ty system consists of four components quality planning, inspection and quahty data collection, quahty assessment and control, and integrated queility management. 

Front-end tools. Chemical reactors, in particular polymer reactors are multivariable, exhibit nonlinear characteristics, and often have significant time delays. In this case the operator cannot easily visualize what is happening in the process, so the computer should aid for visualization of the process state and its relation to the quality of the final product. As the final product quality is measured in the quality control laboratory, not only WYSIWYW (What you see is what you want) interfaces between the operator and the consol are important but WYSIWIS (What you see is what I see) interfaces between the operators (operators at the reactor, at the product formation process, and at the laboratory) are needed to share the information horizontally in the organization. 

---