Fixed Station Data Acquisition Systems

As the name implies, fixed station data acquisition systems are fixed to one location, either because of size or because the wiring makes it very difficult to move the unit. A fixed station DAS can have a wide range of capabilities. A simple DAS may record data from only one extruder, i. e., a dedicated DAS. A number of machine suppliers now offer extruders with integrated data acquisition and SPC capability. 

A more sophisticated DAS may be able to record data from various sources, analyze the data, present control charts, show trend plots for different variables, etc. These systems are often referred to as plant-wide monitoring systems. Central computer-based systems are now available that allow the user to view the operation of plant equipment and change the operating parameters on any selected equipment. A fixed 

Station DAS can take many different forms depending on the application. A good DAS can be a very valuable tool in improving process control as well as in problem solving. For the application of DAS to extrusion operations, the following capabilities are useful  

The different methods of data collection each have their advantages and disadvantages. Check sheets are slow, prone to human errors and transcription errors however, they are also inexpensive, flexible, efficient for small amounts of data, and easy to use. Fixed station data acquisition systems are fast, not prone to human errors and transcription errors, can handle large amounts of data however, they tend to be 

Some plant-wide monitoring systems allow changes to be made by remote control from a central terminal. In such parameters as screw speed or barrel temperature. Obviously, the results from these changes have to be monitored carefully, because they can make the process not only better, but also worse. 

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A simple DAS is a chart recorder that can track important variables like screw speed, diehead pressure, melt temperature, motor amperage, etc. More useful is a computer-based DAS these come in two forms portable data collectors/machine analyzers and fixed-station data acquisition system. 

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