What is the recommended screw design?
You should avoid using rapid compression type screws such as those used for nylon. There should be at least four threads in the compression zone; this number will vary slightly depending on the L/D and compression ratio. Trouble is particularly likely to occur on high revolution extruders equipped with rapid compression type screws with 1 – 3 threads in the compression zone. If the total number of threads is 100, the standard number of threads should be 30-40 for the feed zone, 20-25 for the compression zone and 35-50 for the metering zone.
