EXTRUDER DIES Extruder Sheet and Cast Film The convention between cast film and sheet is that film is less than 0.01 inch thick and sheet is more than 0.01 inch thick. The key components in a sheet/film extrusion line are: die, three-roll stack or cooling rolls, puller or nip rolls, and windup or sheet stacking system. The sheet die should uniformly distribute the polymer melt across the entire die width. This is to provide a uniform melt thickness and polymer flow to the three-roll stack. Die width typically range from approximately 24-120 inches (0.6-3 meters. Cast film/sheet is produced using a multiple roll stack. Depending on the thickness, film is wound in continuous rolls and sheet is cut to length and stacked. The die is designed to fit between the rolls in a three-roll stack and lay the sheet down on the roll. Roll diameters generally range between 8 and 16 inches. Roll stack designs are simple 'up' or 'down' stacks to control the entry and exit angle and th...
THERMOCOUPLE WORKING PRINCIPLE OF THERMOCOUPLE Thermocouple is a temperature measuring device constructed of two dissimilar metal wires joined at one end. When one end of each wire is connected to a measuring instrument the thermocouple becomes a sensitive and highly accurate measuring device. Thermocouple may be constructed of several different combinations of materials. The performance of a thermocouple material is generally determined by using that material with platinum, The measuring junction is normally formed at the bottom of the thermocouple housing. In a typical thermocouple, the leads are encased in a rigid metal sheath. CONSTRUCTION OF THERMOCOUPLE The most important factor to be considered when selecting a pair of materials is the thermoelectric difference between the two materials. A significant difference between the two materials will result in better thermocouple performance. Constantan is excellent for temperature up to 2000℉. Nickel/Nickel-Molybdenum sometimes r...
Fluid Machines The machine that either add energy to the fluid or extract energy from fluid are called fluid machines. They are classified into two categories Positive displacement machine Turbomachines or dynamic machines POSITIVE DISPLACEMENT MACHINE:- are those machine in which energy transfer is accompolished by volume changes that takes place due to movement of the boundaries in which the fluid is confined. TURBOMACHINES:- Fluid device which direct the flow with blades or vanes attached to a rotating member are termed as dynamic or turbo machine. Eg Francis turbine, Centrifugal pump etc Each of these two category or sub classification as pumps and turbines Pump are those machine which add energy to the fluid Turbines are those machines which extract energy from the fluid Some example of positive displacement pump are Reciprocating...
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