Join us at PLAST-EX 2007
May 1-3, 2007
International Center
Toronto, Canada
Booth #416
Sizing
Cages
In the
blown film extrusion process, the sizing cage (aka, sizing
basket, calibration cage or calibration basket) is used to
stabilize the blown film bubble directly over the die and
air ring. Keeping the bubble stable over the die and air ring
improves film quality by ensuring the air ring and internal
bubble cooling effects are uniformly applied to the entire
circumference of the bubble.
As production
rate increases, and in particular, when internal bubble cooling
is used, the sizing cage is a required feature. The higher
production rates require more air flow on the bubble which
results in bubble movement and sometimes complete instability.
A six level cage, like the one shown here provides an excellent
bubble stabilizer.
By
necessity a sizing cage must come into contact with the blown
film bubble in order to stabilize the material. Depending on
the film properties, different styles of contact surfaces can
be specified. This and a variety of other features all need
to be specified when a cage is purchased. Learn
more...
The
key element regarding installation of a sizing cage is the height
of the cage above the blown film die and the proper alignment
over the die. For sizing cages that do not have a vertical height
adjustment, the height position is critical to proper operation
of the line.
Improper cage alignment will cause gauge problems, which can
lead to roll conformation problems. Learn
more...
Sizing cages come in a variety
of designs and costs. Cages are available primarily through
blown film extrusion manufacturers. Although there are at
least two independent sizing cage manufacturers.
Click here
for a list of cage manufacturers compatible with the IS-IBC1
non-contact IBC control system.
