Coextruded multilayer distribution
Vol. 26 #1, March 1999
Many sheet and film lines have from 3 to 7 layers and sometimes more. One way to tell layer distribution is with an optical microscope for thick samples and SEM for thin samples.
Thickness distribution can be measured in the TD and MD directions with these techniques. An on line check of average layer thickness can be done with weigh feeders. If you do not have a weigh feeder and feed your hopper from a drum or Gaylord box, put the drum or box on a scale and record the loss of weight over a 10 to 15 minute period (or longer). This will give the actual flow rate for that extruder under production conditions. Average layer thickness is then calculated by knowing how much product is produced in a given time.
- John Wagner, JVW Enterprises, Inc.
See also:
- Casting of extruded semi-crystalling film and sheet
- Estimating flow rate of a continuous sheet line
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