Statistical process control system

Control System Included in this classification are Supervisory Control and Data Acquisition Systems (SCADA), Distributed Control Systems (DCS), Statistical Process Control systems (SPC), Programmable Logic Controllers (PLCs), intelligent electronic devices, and computer systems that control manufacturing equipment or receive data directly from manufacturing equipment PLCs. 

To prevent material loss due to excursions such as the previous example, robust process control systems are required throughout the supply chain from the raw materials manufacturer to the pad manufacturer and the CMP module. Invariably, incident reviews of such excursions reveal that the excursion could have been prevented or limited to only a small amount of material lost if the proper statistical process control systems had been in place. Invariably, the excursion could have been detected by careful scrutiny of an in-process parameter that was either monitored or should have been monitored by the subsupplier, pad manufacturer, and/or the CMP operation. 

Trendcheck [Nalco], TM for real-time statistical process control system. 

Currently more challenging is the integration of in-line analytics into a statistical process control system (SPC) [6]. As part of an automated microreaction process, this would allow active regulation of the process and would result in long-term quality, robustness and safety. 

From the data obtained, a variety of statistical figures may be determined, including the detection limit, the accuracy, the recovery in typical sample matrices (hence identifying any matrix effects) and the precision (within and between batch). Furthermore, an ongoing statistical process control system can be set up for day-to-day quality control purposes. This normally... 

Fig. 4.12. Statistical process control chart for TXRF measurement systems. The sensitivity of the system can be controlled by daily calibration with an...

Failure modes analysis Statistical process control Measurement systems analysis Employee motivation On-the-job training Efficiency will increase through common application of requirements for Continuous improvement in cost Continuous improvement in productivity Employee motivation On-the-job training... 

The alternative is hexane, which because of the explosion hazard requires a more expensive type of extractor construction. After the extraction the product is dull gray. The continuos sheet is slit to the final width according to customer requirements, searched by fully automatic detectors for any pinholes, wound into rolls of about 1 m diameter (corresponding to a length of 900-1000 m), and packed for shipping. Such a continuous production process is excellently suited for supervision by modern quality assurance systems, such as statistical process control (SPC). Figures 7-9 give a schematic picture of the production process for microporous polyethylene separators. 

Quality systems/statistical process control Toll chemistry Management of change Logistics Invoicing... 

Section 9.2 will review traditional statistical process control/statistical quality control (SPC/SQC) techniques used in quality control. Section 9.3 will follow this review with a discussion of techniques based primarily on an experiential rule base and expert system technology. Section 9.4 will discuss control strategies that use an on-line process model a variety of models can be used in such model predictive control. Section 9.5 will discuss this variety of models. Section 9.6 will summarize this chapter and discusses future trends in the field. 

Is there a computerized, analytical results tracking and graphing system [process management software or statistical process control (SPC)] in place, as well as manual checks ... 

A bioprocess system has been monitored using a multi-analyzer system with the multivariate data used to model the process.27 The fed-batch E. coli bioprocess was monitored using an electronic nose, NIR, HPLC and quadrupole mass spectrometer in addition to the standard univariate probes such as a pH, temperature and dissolved oxygen electrode. The output of the various analyzers was used to develop a multivariate statistical process control (SPC) model for use on-line. The robustness and suitability of multivariate SPC were demonstrated with a tryptophan fermentation. 

Manufacturing information systems for real-time process control in the lab and for efficient statistical process control, as well as the right number of lab trials, limits information losses between the plant and the labs. Parallel synthesis, such as units with online analytics in the lab, and the use of new technologies such as Micro Reaction Technology developed by Clariant and a few other companies for application in production mean a step change in reproducibility. 

In this way, the AuMpRes process control system can perform systematic variations of process parameters based on predefined statistical DoEs (design of experiments) [108],... 

Develop a metrics system allowing for quantifiable results wherever possible for example, use statistical process control charts for manufacturing processes and correlating manufacturing deviations with consumer complaint trends. 

Statistical process control methods are applied to preparative chromatography for the case where cut points for the effluent fractions are determined by on-line species-specific detection (e.g., analytical chromatography). A simple, practical method is developed to maximize the yield of a desired component while maintaining a required level of product purity in the presence of measurement error and external disturbances. Relations are developed for determining tuning parameters such as the regulatory system gain. 

Engineering process control is not generally the same as quality control or statistical process control engineering control is intended to continuously reject and attenuate errors which enter while the process operates, while most statistical control techniques seek to identify sources of error so that they may be eliminated by subsequent process or operation revisions. At times the two approaches are in conflict, for by correcting or compensating for a disturbance an engineering control system may distort the statistical parameters used in quality control analysis. 

The Shotscope system also maintains and displays statistical process control (SPC) data in a variety of formats, including trend charts, X-bar and R charts, histograms, and scatter diagrams. This information provides molders with the knowledge that their processes are in control, and, should they go out of control, Shotscope can alert to an out-of-control condition and divert suspect-quality parts. Furthermore, because the Shotscope system can measure and archive up to 50 process parameters (such as pressures, temperatures, times, etc.) for every shot monitored and the information archived, the processing fingerprint for any part can be stored and retrieved at any time in the future. This functionality is extremely important to any manufacturer concerned with the potential failure of a molded part in its end-use application (for example, medical devices). 

The intent in this chapter is not to present in great detail the mathematics behind the statistical methods discussed. An excellent reference manual assembled by the Automotive Industry Action Group (AIAG), Fundamental Statistical Process Control, details process control systems, variation, action on special or common causes, process control and capability, process improvement, control charting, and benefits derived from using each of these tools. Reprinted with permission from the Fundamental Statistacal Process Control Reference Manual (Chrysler, Ford, General Motors Supplier uality Requirements Task Force , Measurement Systems Analysis, MSA Second Edition, 1995, ASQC Press. 

Quality assurance is an important consideration for the user and producer. Both aspects are discussed by Puls (17) in his symposium paper. Lot-to-lot variations in purchased catalyst can be minimized by a system of statistical process control by the catalyst producer, his supplier, and the user. The statistical process helps to minimize product quality variations by instituting corrective action on a real-time basis to prevent the production of off-specification material. 

In any process, regardless of how well designed or maintained, a certain amount of natural or inherent variability will exist. This natural variability has been called a stable system of chance causes. A process operating with only chance causes is said to be in statistical control, and the variation is said to be because of common causes. Statistical process control evaluates whether or not a process is in statistical control with respect to one or more process or product characteristics. 

Blaivas (B4) described the use of an IBM-1710 process-control system, on-line to 20 AutoAnalyzers, in which the computer program included instructions for the acceptance or rejection of standard curves, and a series of checks for monitoring the acceptability of values obtained for control sera. Any results that failed to meet the requisite criteria were indicated within a few seconds of the charting of a peak by a message typed on an on-line typewriter. This system has the ability to include daily statistical assessments of the quality of results, but these possible additional control features were not listed in the description (B4). 

Up to the present time it has not been possible to demonstrate the ultimate reliability of characterizations based on random disturbances. However, the use of random disturbances offers great potential advantage in studying existing process control systems where upsets like step disturbances cannot be tolerated. Because of the extensive calculation required to reduce the random operating records to statistical-correlation functions, high speed digital computation is essential in this treatment. 

The principles utilized in these expert systems are general purpose and based on failure modes, effects and critically analysis, FMECA, a sub-process of reliability centred maintenance, RCM, and statistical process control, SPC. The analysis paradigm includes ... 

Consider using statistical process control, reexamine the types and locations of sensors, and use the four basic levels of control (1) basic process control system, (2) alarm system,... 

Contents indude mathematical modeling, process control, statistics, hierarchical control systems, artifidal Intelligence techniques, knowledge-based expert systems, and modeling of large scale systems using the general purpose simulator. 

Implement advanced micro-fabrication processing methods and statistical process control Evaluate environment-tolerant protective coatings Investigate catalytic chemistry at sensor surface Examine the phase transformation mechanism of the sensing materials Develop integrated system solution... 

M. Reis, P. Saraiva, Heteroscedastic latent variable modelling with applications to multivariate statistical process control, Chemometrics and Intelligent Laboratoy Systems 80 (2006) 57-66. 

To date, process control systems like Programmable Logic Controllers (PLCs) have only enabled paperless operation in combination with SCADA (Supervisory Control and Data Acquisition) systems or as part of a DCS (Distributed Control System), which enable measurement and control actions to be recorded and used as part of batch documentation. Process control systems have the advantage that they focus on real-time data as a necessary part of both control and supervision. The real-time focus is very useful for implementing both active and proactive control when combined with, for example, statistical tools or predictive algorithms. 

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