Asset optimization through data variation analysis.Application: The proposed "fingerprint" technique can identify the sources of problematic sheet variation, allowing the papermarker to take corrective action A corrective action is a change implemented to address a weakness identified in a management system. Normally corrective actions are instigated in response to a customer complaint, abnormal levels if internal nonconformity, nonconformities identified during an internal audit or . Sheet variation is inherent to the papermaking process. Common sources of variation include bad valves, poor mixing, faulty transmitters, excessive mechanical vibration Mechanical vibration The continuing motion, repetitive and often periodic, of a solid or liquid body within certain spatial limits. Vibration occurs frequently in a variety of natural phenomena such as the tidal motion of the oceans, in rotating and stationary , and improperly tuned controllers. Excessive variation cuts into the mill's profit margin by reducing machine productivity (sheet breaks, lower machine speeds) and compromising sheet quality. While sheet variation cannot be eliminated, it can be controlled within acceptable limits. All paper machine monitoring and control system output a statistical report at the end of each reel of paper. These reports include useful information about the machine and cross-direction (MD and CD) variation in the sheet, but this provides only a snapshot into what is going on in the machine. The reel statistics are of little help in deciding where to focus resources for troubleshooting machine problems. This paper presents a technique for quantifying paper machine performance well beyond statistical reel report data. Using this tool, the papermaker can identify sources of problematic variation and take corrective action. The fingerprint The "fingerprint" is a technique for studying process variation in both the MD and CD. Data are collected from the quality control system, distributed control system A distributed control system (DCS) refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component , and individual instruments. Where system processing speeds are limited, high-speed data logging (data) data logging - (data acquisition) Storing a series of measurements over time, usually from a sensor that converts a physical quantity such as temperature, pressure, relative humidity, light, resistance, current, power, speed, vibration into a voltage that is then converted of sensor signals is performed with special equipment. The logged data are processed to obtain a time series in engineering units. Using Fourier analysis Fourier analysis n. The branch of mathematics concerned with the approximation of periodic functions by the Fourier series and with generalizations of such approximations to a wider class of functions. , each time series is expressed as a sum of sinusoids of varying amplitude frequency, and phase, with each contributing a known variance or power to the signal. The MD variations are divided into six frequenc bands (decades) spanning the range 0.0001-100 Hz, as seen in Fig. 1. The decade in which variation appears provides insight into the source of variation. Note that the area covered by a typical reel report (shaded area) monitors only decades 2 and 3 (frequency rang 0.001-0.1 Hz) while excluding the information in decades 1, 4, 5, and 6. In order to benchmark a a machine's performance, variation in the CD and in all six decades of the MD must be measured. [FIGURE 1 OMITTED] Mill application Figure 2 is a fingerprint showing the CD and MD variation in a tissue mill before and after fine tuning Fine Tuning is the name of XM Satellite Radio's eclectic music channel. The program director for Fine Tuning is Ben Smith. The channel is described as "A musical oasis for the sophisticated listener culled from every imaginable genre and country. of controls. Most of the problems with this machine had to do s with stock prep, actuator-level controls, and scan-level controls. After extensive control and process work, the overall COV COV Composés Organiques Volatiles (French) COV Compuestos Orgánicos Volátiles (Spanish: Volatile Organic Compounds) COV Coefficient of Variation COV City of Villians (game) (coefficient of variation Coefficient of Variation A measure of investment risk that defines risk as the standard deviation per unit of expected return. ) on the tissue machine was cut in half. The CD variation was reduced considerably, but it remained high because the mill only had manual control of the actuators. The reduction in CD variation was obtained by manual adjustments of the actuators. This mill would be a good candidate for automatic CD control. [FIGURE 2 OMITTED] Conclusion A fingerprint can be a useful tool for establishing machine performance before and aider major machine changes, when assessing the need for capital equipment purchases, or when determining if further control work is necessary. The fingerprint can also identify where money should be invested to improve sheet quality and machine runnability. Starr is process optimization Process optimization is the practice of making changes or adjustments to a process, to get results. Optimization is the use of specific techniques to determine the most cost effective and efficient solution to a problem or design for a process. development manager at ABB n. 1. Among weavers, yarn for the warp. Hence, Noun 1. ABB - an urban hit squad and guerrilla group of the Communist Party in the Philippines; formed in the 1980s Inc., 650 Ackerman Rd., Columbus, OH 43202. Address correspondence to Start by email at kevin.start@us.abb.com |
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