Process Control Capabilities Research Articles

A methodological approach for model validation in faster than real-time simulation

When successfully dealing with time constraints, faster than real-time simulation (FRTS) improves process control capabilities through providing short-term predictions. Validation of a simulation model is accomplished through comparing system observations and model data corresponding to the same time points. A methodological approach is necessary for the realization of this comparison, considering the time-dynamic system behaviour and the potential deviations between the model and the system. A seven-step method is proposed, emphasizing the following issues: determining when predictions should be considered as valid, accomplishing validation on the basis of the available model and system data, considering that not all deviations between the model and the system are of equal significance, and indicating potential system changes, so that the model can be modified in real time. Computer networks are used as an example domain, due to their multi-entity structure and time-dynamic behaviour, offering excellent test cases for evaluating the proposed method. Experimental FRTS results from the application of the proposed method to the network domain are also presented.

Analytical Method of Process Capability for Steel

The mechanical properties of steel are the most important factor in the safety of structures that must be stable and appropriate. In order to investigate whether the process capa- bility of steel production meets the quality requirements or not, Sung et al. proposed a procedure to evaluate the production and quality control of steel manufacturing. This evaluation model uses statistics to judge the quality of steel objectively. However, there are various types of steel which can satisfy the engineering requirements of design and con- struction, but procedures are lacking with which to evaluate the multi-process capability of the whole steelwork. In this paper, the objective evaluation methods proposed by Sung and Vannman are modified appropriately and extended by using the principles of statistical inference. A procedure to evaluate the quality of the multi-process capability analysis method is proposed. This evaluation method not only completely evaluates the process capability and quality, but it also improves the production process and quality control capability, and so can reduce production loss. A steel structure is more reliable than a wooden structure or a reinforced concrete structure for resisting earthquake-induced forces (1,2). According to these results, steel will be widely used in the construction industry in Taiwan and Japan. Carbon steel, high strength-low alloy steel and heat treatment-low alloy steel are often used as constructional materials for frame structures. Additionally, in order to promote the earthquake resistance capability of a structure, new steels for construction have been developed such as: low yielding ratio steel; narrow yielding stress variation steel; and low yielding stress steel. To increase the strength and provide special functional characteristics to steel, alloying elements other than carbon are added to produce steels of various yielding stress. Quenching and tempering heat treatment procedures can also be used to obtain higher yielding steel. The key aspects of the production process are puddling and heat treatment after crushing. These techniques affect the mechanical properties of the steel. In order to ensure the quality of the steel, the analyses of chemical composition and mechanical behaviour are tested. The test of steel monotonically loaded in tension is widely used to ascer- tain the quality of steel that has a major effect on the safety of structures. Although there are some analytical methods for evaluating the production process control of steel, there is still a lack of evaluation methods to estimate the efficiency of the production processes control involved. The purpose of this work is to propose a procedure to evaluate the quality and control capability of the multi-processes of steelworks. At this time, many new evaluation methods are continually being developed to enhance the analysis and the evaluation of a satisfactory production process, for the loss function of the production process and for the index of production capability. The technology of engineering quality analysis is very mature for assessing the production capability. Effective methods for evaluating production processes are provided by many workers such as Kane (3), Chan et al. (4), Chou and Owen (5), Boyles (6), Pearn et al. (7), Boyles (8), Greenwich and Jahr-Schaffrath (9), and Chen (10). Sung et al. (11) proposed indices of accuracy and precision to evaluate the quality and tensile strength of steel bars. A new index, the quality index, for the tensile strength of steel reinforcing bars is created to evaluate the production quality and efficiency of steel bar manufacture by combining these two indices. This method is useful for

Development of a Resin Transfer Molding Test‐bed with Process Control Capability

AbstractFiber reinforced plastic parts have traditionally been manufactured by resin transfer molding. This method is based on a fixed recipe and no attempt is made to control process conditions during the manufacturing process. In this paper, an experimental test‐bed is developed which has the capability of implementing a wide variety of temperature and pressure profiles for the manufacture of plastic parts via resin tranfer molding. The performance of the test‐bed is evaluated by implementing several desired pressure and temperature profiles in production of fiber reinforced polyester parts.

Effects of Borophosphosilicate Glass Dopant Concentrations on Isotropic Etch Profile

AbstractIn the process of chemically etching contact openings, film characteristics of the Borophosphosilicate glass (BPSG) film strongly effect the formation of an ideal contact profile. Ideal contact profiles represent a wine glass shape to provide better metal step coverage into the contact opening in comparison to a vertical sidewall profile. The rounded shape of the wine glass is etched chemically (isotropic) allowing for etch in the vertical and horizontal direction. As the addition of dopants to the oxide film effect the etch rate, the profile of the isotropic etch will change which in turn effects the electrical device properties, down stream processes and device reliability.BPSG film characteristics are the area of investigation. Characteristics of concern are weight percent concentrations of boron and phosphorus, film density and dopant concentration profiles in relation to depth. To evaluate the entire contact formation module, chemical etch characteristics including etch rate in relation to film depth for thermal oxide films were also investigated. Experimentation in the form of a response surface design was used to model effects of previously discussed BPSG film characteristics.To achieve the desired and predictable wet etch rate of BPSG in a buffered oxide etch (BOE), calculated control limits were placed on the boron and phosphorus dopant concentrations. Results showed that dopant effects on the isotropic etch process exceeded the control capability of dopant concentrations in the deposition process. In relating process control capabilities to 6σ techniques, a Cpk above 1.5 is considered capable. To eliminate previously discussed defects created in the isotropic etch process, reject limits for dopant concentrations in a BPSG film deposition process would need to be set well within the typical 6σ giving a Cpk below 1.5

The numerical modelling and process simulation for the fault diagnosis of rotary kiln incinerator.

The numerical modelling and process simulation for the fault diagnosis of rotary kiln incinerator were accomplished. In the numerical modelling, two models applied to the modelling within the kiln are the combustion chamber model including the mass and energy balance equations for two combustion chambers and 3D thermal model. The combustion chamber model predicts temperature within the kiln, flue gas composition, flux and heat of combustion. Using the combustion chamber model and 3D thermal model, the production-rules for the process simulation can be obtained through interrelation analysis between control and operation variables. The process simulation of the kiln is operated with the production-rules for automatic operation. The process simulation aims to provide fundamental solutions to the problems in incineration process by introducing an online expert control system to provide an integrity in process control and management. Knowledge-based expert control systems use symbolic logic and heuristic rules to find solutions for various types of problems. It was implemented to be a hybrid intelligent expert control system by mutually connecting with the process control systems which has the capability of process diagnosis, analysis and control.

An Expert System for LD Steel Making

LD process of stealmaking accounts for 70% of steel production throughout the world. Due to various constraints like the complexity of LD process; variation in quantity, quality and grade of input materials; varying operating conditions, random parameters and their values; the interventions of an expert and skilled operator is necessary to tackle the complex situation. To overcome this, there exists, a need of a system, which does not only possess the process control capabilities, but also emulates operator's expertise in terms of his knowledge and skill. Such a system has been developed named “Expert Steelmaker”. The paper discusses the “Expert Steelmaker” which can presently be used in an advisory mode by the LD steelmaking operator.

Implementation of statistical process control and process capability studies: Requirements or free will?

Focuses on whether requirements from customers or other reasons cause organizations within industries in Sweden to implement statistical process control and/or process capability studies. Requireme ...

STATISTICAL CHARACTERIZATION OF A DIE SHEAR TEST

[This abstract is based on the author's abstract.] Traditional statistical quality control methods rely heavily on the normal distribution. This model has two major practical applications: statistical process control (SPC) and process capability anal..

Tungsten Chemical Mechanical Polishing Endpoint Detection

Conventional methods of controlling tungsten Chemical Mechanical Polishing (WCMP) processes have included blanket wafer polish rate and platen temperature monitoring. In order to enhance process control of WCMP, a second generation motor-current sense endpoint system was chosen as the evaluation tool. The endpoint detection system (Luxtron 9300) was installed on a WCMP polisher (IPEC 472) at the Motorola MOS6 facility. Endpoint algorithms were evaluated under various polishing conditions during time periods between pad changes. The data collected over 3 months led to a reliable endpoint recipe for both the contact and via WCMP process. The endpoint data compared with the conventional timed recipe, indicated that a time reduction at WCMP could be achieved, with a 10% increase in throughput. In addition, contact and via W-plug endpoint data showed a strong signal versus pattern density for given device types. In summary, the motor current endpoint system tested verified reliable endpoint, process control, and characterization capabilities.

Multichannel process monitor for real-time film thickness and rate measurements in dry etching and deposition

The versatile multichannel process monitor system, MPM- X, designed for the online control of plasma and ion beam etching and deposition is introduced. It provides a number of in situ process data like etch rate and selectivity, deposition rate, film thickness, uniformity and endpoint. This is achieved by an integration of optical emission spectroscopy (OES) and optical interferometry, where no external light source is required. By using the plasma itself as a light source for the wafer illumination, a large number of wavelengths, ranging from the deep ultra violet to the near infrared, is available for the interferometric process control. The process control capabilities of the MPM- X system are demonstrated in this paper for various etch and deposition applications.

Advances in metallocene polymers for wire and cable applications

When combined with manufacturing and process control capabilities, these metallocene catalysts have created new polymers that are being used in a variety of applications, including wire and cable insulation and jacketing.

AIRCRAFT ACQUISITION AND OPERATION IN A TOTAL QUALITY ENVIRONMENT Part II: Process Modeling and Improvement

In part I of this work, a conceptual framework and approach for handling the problem of aircraft acquisition and operation in a total quality environment was presented. Decisions related to aircraft acquisition or operation are usually based on predicting the expected performance of Aircraft Mission Support Process (AMSP). The objective of part II is to present the modeling approach and improvement procedure of this process. The model is developed such that it can provide sampling experiments required for the application of Statistical Process Control (SPC) and process capability measures. A process capability index is used to measure the capability of the process in providing the system user with the required level of performance. Aircraft operational availability is taken as the process external performance indicator (or quality characteristic). A simple analytical model is investigated to determine its adequacy for the intended statistical analysis. Simulation is adopted as the preferred approach to model the process. Different acquisition options for improvement are evaluated by changing the design, support, and/or operational characteristics of the acquired system. For each option it is possible to determine the benefit and the worth of the change. Results of application of this approach show its power in predicting the process future performance. The suggested model could also provide an interfacing mechanism between aircraft users and suppliers in support of their mutual decision making during aircraft acquisition or operation.

AIRCRAFT ACQUISITION AND OPERATION IN A TOTAL QUALITY ENVIRONMENT Part I: A Conceptual Framework and Approach

A conceptual framework and an approach for handling the problem of aircraft acquisition and operation in a total quality environment are proposed in this part of the work. For this purpose, a typical acquisition process is described and the system operational and maintenance support requirements are summarized. The Aircraft Mission Support Process (AMSP) is analyzed at different levels of detail to identify the problem symptoms, causes, statement, problem solving approach and the design alternatives. This provides the necessary background and foundation for establishing a Logistic Engineering Model to support the decision making during aircraft acquisition and operation. Statistical Process Control (SPC) and process capability measures are utilized in the decision making process. To support this concept, the intended model is further developed to provide sampling experiments to pursue the required statistical analysis. This is done by using aircraft operational availability as the external performance indicator for the Aircraft Mission Support Process. Internal performance indicators are also considered. This approach can provide a mechanism for evaluation of different acquisition and/or operation options directed to continuous improvement of aircraft readiness and utilization. Part II of this work presents (AMSP) modeling and improvement procedure.

The role of intelligent systems in weld process control

In materials processing, the process parameters are generally controlled based on knowledge of the relationships between the parameters and the desired material properties. Post-processing quality control is then used to determine if the processing was successful. A primary goal of intelligent sensing and control is to bring quality control into the process by incorporating sensing capability, knowledge of process physics, control capability, and process engineering such that the intelligent processing system is aware of the state of the process and knows how to make a good product based on that awareness. Methods of incorporating intelligent systems, such as fuzzy expert systems and artificial neural networks, into control schemes are discussed along with standard classical and modern control theory. The methods of intelligent systems such as neural networks and fuzzy systems are often means of generating an input-output mapping function. An example of an intelligent control system employs both fuzzy logic and a neural network to control heat input and mass input in gas metal arc welding (GMAW). Two cameras are used to measure the area of the joint to be filled and the temperature gradient in the solidified weld metal. This information is processed by a fuzzy logic system tomore » determine the required mass to fill the joint and the heat input to the weld to maintain a specified cooling rate. This information is processed by neural network which maps this to the welding parameters, travel speed and electrode speed. Hardware, actuators on the weld machine then implement the require values.« less

Rapid Thermal Processing Requirements for 0.35-µm IC Technologies and Beyond

ABSTRACTThis paper will present an overview of rapid thermal processing (RTP) technologies for fastcycle-time IC production. RTP has experienced significant advances in equipment design, process control capabilities, and unit process applications over the past eight years. The Microelectronics Manufacturing Science and Technology (MMST) program at TI successfully demonstrated CMOS IC production in a single-wafer factory with all-RTP thermal fabrication for various anneals, oxidations, and chemical-vapor depositions. The use of RTP in conjunction with other single-wafer processes enabled 0.35 µm IC fabrication with a 3-day cycle time. Selected RTP equipment, sensor, and process control developments will be reviewed. The RTP applications and requirements for state-of-the-art and future IC technologies will be described.

Emerging chemical sensor technologies for use in on-line applications

Advances in instrumentation and process control capabilities are being driven by the increased sensitivity of analytical chemistry methods, the commoditization and ruggedization of instruments and associated electronics, and changing consumer concerns and expectations, as well as government regulations. The emergence of biotechnology methods for the detection of contaminants, as well as the miniaturization and ruggedization of more standard analytical instruments based on mass spectrometry and infrared spectroscopy are discussed as related to on-line process monitoring.

The Pulse of Pultrusion: Pull Force Trending for Quality and Productivity Management

A large number of studies in recent years have focused on the significance of the thermal environment within the pultrusion die and the effects of process parameters on the reaction of thermosetting resins within the die. Numerical models have been proposed which can simulate internal exothermic reaction dynamics for simple shapes. The rate and position of reaction can be predicted given thermal inputs and considering the heat transfer characteristics of the die, material, and profile geometry. On a practical plane, commercial instruments have been developed which allow the processor to easily conduct thermal analysis experiments which can measure the reaction characteristics for more complex profiles not within the current predictive realm of computer models. Another area of investigation which has recently received attention is the influence of internal die pressures on processability and product quality. A variety of methods have been employed to quantify the internal pressures on both a continuous and intermittent basis. A number of investigators have studied the effects of different raw materials on frictional resistance within the die and have measured the resultant pulling force required to overcome the resistance. The results of such studies have established that internal pressures are substantial and desirable for good product integrity and dimensional reproduction. They have also established that there are numerous contributions to frictional resistance that are difficult to measure independently and even more difficult to model numerically. Such a model when perfected could be useful in helping to optimise materials and die design which would help to minimize internal porosity, improve surface quality, and reduce internal stress imbalances that result in dimensional tolerance problems. However, as is the case with pultrusion heat transfer models, simplifying assumptions often limit the applicability of a model's predictions. In lieu of a technique to segregate the component causes of pulling resistance, the measurement of the pultrusion machine pulling force is an extremely useful tool for the processor. Factors which can cause changes in the pulling force include a loss or excess of reinforcement, poor fibre wetout, change in resin reactivity or viscosity, loss of temperature, or change in line speed. The stability of pull force, therefore, becomes a valuable operator diagnostic tool when displayed as a graphical historical trend line. Coupling such a display with a high-load alarm to signal the machine operator to process threatening conditions provides an important process monitor and control capability. Additional benefits of pull load and line speed trending can be realized by the production supervisor and the process engineer who are charged with optimising productivity and quality. This paper describes the use of pull force measurement techniques and commercial equipment which is now available to establish this necessary process insight. Practical examples of the use of this methodology are provided.

The Pulse of Pultrusion: Pull Force Trending for Quality and Productivity Management

A large number of studies in recent years have focused on the significance of the thermal environment within the pultrusion die and the effects of process parameters on the reaction of thermosetting resins within the die. Numerical models have been proposed which can simulate internal exothermic reaction dynamics for simple shapes. The rate and position of reaction can be predicted given thermal inputs and considering the heat transfer characteristics of the die, material, and profile geometry. On a practical plane, commercial instruments have been developed which allow the processor to easily conduct thermal analysis experiments which can measure the reaction characteristics for more complex profiles not within the current predictive realm of computer models. Another area of investigation which has recently received attention is the influence of internal die pressures on processability and product quality. A variety of methods have been employed to quantify the internal pressures on both a continuous and intermittent basis. A number of investigators have studied the effects of different raw materials on frictional resistance within the die and have measured the resultant pulling force required to overcome the resistance. The results of such studies have established that internal pressures are substantial and desirable for good product integrity and dimensional reproduction. They have also established that there are numerous contributions to frictional resistance that are difficult to measure independently and even more difficult to model numerically. Such a model when perfected could be useful in helping to optimise materials and die design which would help to minimize internal porosity, improve surface quality, and reduce internal stress imbalances that result in dimensional tolerance problems. However, as is the case with pultrusion heat transfer models, simplifying assumptions often limit the applicability of a model's predictions. In lieu of a technique to segregate the component causes of pulling resistance, the measurement of the pultrusion machine pulling force is an extremely useful tool for the processor. Factors which can cause changes in the pulling force include a loss or excess of reinforcement, poor fibre wetout, change in resin reactivity or viscosity, loss of temperature, or change in line speed. The stability of pull force, therefore, becomes a valuable operator diagnostic tool when displayed as a graphical historical trend line. Coupling such a display with a high-load alarm to signal the machine operator to process threatening conditions provides an important process monitor and control capability. Additional benefits of pull load and line speed trending can be realized by the production supervisor and the process engineer who are charged with optimising productivity and quality. This paper describes the use of pull force measurement techniques and commercial equipment which is now available to establish this necessary process insight. Practical examples of the use of this methodology are provided.

Emerging chemical sensor technologies for use in on-line applications

Advances in instrumentation and process control capabilities are being driven by the increased sensitivity of analytical chemistry methods, the commoditization and ruggedization of instruments and associated electronics, and changing consumer concerns and expectations, as well as government regulations. The emergence of biotechnology methods for the detection of contaminants, and the miniaturization and ruggedization of more standard analytical instruments based on mass spectrometry and infrared spectroscopy will be discussed as related to on-line process monitoring.

Interactive posters

A multi-year, interdisciplinary effort is currently in progress to assist the design of effective human-computer interaction (HCI) for systems with real-time process monitoring and control capabilities shared between human and computer agents. Based on observations and experiences from this research, a persistent problem in the design of such systems is inadequate consideration of HCI requirements.