Controlled shrinkage dryer CA-85

The CA-85 dryer represents an important step in the improvement of drying technology, specifically to process both tubular and open width knitted fabrics, and also a wide variety of woven and non-woven fabrics.
ALEA, textile drying specialists since 1881, have designed this machine to meet the growing demands for "dimensional stability" and "improved handle" of knitted fabrics.

We would like to point out the main technical features of this machine as follows:

  • structure: designed to resist mechanical and thermal stress
  • insulation: designed to minimize heat losses
  • air circulation: designed to produce symmetrical ariflow with minimal pressure drops. Re-circulated air is filtered, heated, and blown by high performance fans into delivery channels
  • air nozzles: they are specifically designed to create a warm air vibrating cushion in which the drying process takes place with excellent output. The symmetrical airflow holds the fabric in open, crease-free form with selvedges uncurled
  • heating system: machine can be supplied for heating by steam, superheated water, diathermic oil, or direct gas
  • exhaust system: for machines with standard filters damp air is exhausted via ductwork fitted with butterfly valve to control quantity of exhausted moist air
  • automation: drying temperature is maintained at preset values by a temperature controller with automatic control valves. Fabric speed is controlled by a DC drive system, easily adjusted by potentiometer from the operative position. A DC driven feed roller provides overfeed adjustment between -10% and +40% according to fabric shrinkage. Fabric take-off is also by DC drive and both overfeed and take-off are adjustable by potentiometer from the operative position. Speed ratio between feed and take-off is automatically maintained when fabric speed is adjusted
  • stainless steel conveyor belt: designed for strength and to allow maximum airflow. The belt is driven directly by sprockets running the width of the machine, thus avoiding the need for belt centering devices
  • DC motors: they ensure smooth running and perfect synchronisation of overfeed speed and take-off speed.

The first picture shows the outlet side of a machine comprising three chambers, each of three meters length, heated with diathermic oil and specifically designed to dry silk fabrics.

The second picture shows one of many plants set up in the United States. It comprises four dryers, each with four sections. Modularity is one of the advantages of the CA-85. Additional chambers may be added to the original machine at later stages to provide an ultimate of six section machine.

The other pictures show:

1. Detail of the stainless steel belt and the fabric as it is conveyed during drying. Note that the belt mesh is very open, thus avoiding any reduction in airflow to the underside of the fabric. Hence, this ensures uniform drying to both side of the fabric. In fact the design of the mesh is such as to straighten the airflow and direct it on to the fabric.

2. Fabric laid out on the belt inside the dryer. Notice the "wavelength" of the fabric, which can be varied by adjusting the inlet overfeed. The combination of air agitation, temperature and moisture in the fabric allow the knitted fabric to relax in tensionless form to its natural state, giving improved dimensional stability.
Note also that the wave motion of the fabric avoids permanent contact with the belt and possible marking.

3.Detail of the inlet equipped with expander for light and open fabrics.

In the picture:

Cross selection of a CA-85. It can be supplied with 1600, 2000, 2400 or 2800 mm useful width.

Longitudinal section of one CA-85 chamber.
The picture shows the position of air filters and heating batteries. Both are easily accessible for cleaning and maintenance.

After passing through the moist fabric, air is re-circulated by fans, blown by filters for lint removal, then via heat exchangers or gas burner chambers. The reheated air is then directed once again on to the fabric via the special nozzle system fitted above and below the stainless steel belt. The proportion of moist air exhausted via the chimney or exhaust duct is controlled by a butterly valve.

Side view of a three chamber CA-85 with inlet overfeed roller and outlet plaiter. The picture shows the large doors on both sides of the machines for easy access to inner parts.

Front view of a CA-85 with 2800 mm belt useful width. Of course, the total width of the dryer varies according to the belt useful width.