On the cover:
continued from cover
Moisture (extrudate, dried). ■
It is important to note that

For a truly comprehensive
When reviewing the proper drying solution
This issue will focus on
these are not standalone criteria

extrusion program, your

for your application, all parameters need to be
temperature and airflow. The
to be considered exclusively.

demanding processes must

considered:
remaining parameters—retention
Multiple relationships exist among

be complemented with an
appropriate drying solution.
Temperature;■
Airflow management (direction, volume, ■
time/bed depth, product size
and moisture—are product and
parameters, and though they may
not be directly proportional, they

velocity);
Retention time and bed depth; ■
Product size; ■
rate specific; we will address their
management in a future issue of
The Extru-Technician.
will indirectly bias the result of
others.

Figure 1.
Drying curve with air temperature of 90°C
11.8min Temperature Moisture 85 80 75 70 65 60 55 30.00 25.00 20.00 15.00 10.00 5.00 Air Temperature 90°C
Product Moisture (%MCWB)
Product Temperature (°C )
0.00

16 18 14 10 12
Drying Time (Mins)
Graphs such as this show a product-specific curve relating drying time,
moisture and air temperature.
Figure 2.
Drying curve with air temperature of 115 °C
Product Temperature (°C)
Product Moisture (%MCWB)
25.00 110 Air Temperature 115 °C 105 20.00 100 5.00 10.00 15.00 65 70 75 80 85 90 95 Temperature Moisture 5 min
0.00

Drying Time (Mins)
With the temperature optimized, other drying parameters can be
manipulated into an economically favorable set of operating ranges.