Basic Terms of fabric preparation equipment

Batch Machines:

In batch processing, machines are used where the entire load of fabric is
immersed in the total amount of liquid needed for that process. These machines are
primarily used to dye fabric, however, in many cases they are also used to prepare
fabric prior to the dyeing cycle. The section that follows describes some of the more
popular machines.

1. Becks

A beck is the simplest type of wet processing batch equipment. It is a large vat
which holds the entire lot of fabric. The fabric is fed into the machine in the form of
a rope and is made into a continuous loop by sewing the two ends together. The
length of the loop is equal to a piece length, usually 100 to 200 yards. The fabric is
agitated by the action of a lifter wheel which gently moves the fabric through the
liquor by lifting and dropping the rope in and out of the liquor. Lot size is
determined by the number of loop strands that can be accommodated by the machine
and is a function of the front width of the machine. Commercial machine are
available ranging from one strand to 16 strands. A schematic of a beck is shown in
figure.

Schematic of an Atmospheric Beck

2. Jet Machines

Jet machines are similar to becks in that a continuous loop of fabric circulates
through the machine. They differ however in that a stream of liquor is forced
through a venturi tube. This provides the force to propel the fabric through the
machine. Temperatures in Jet machines that operate at atmospheric pressure cannot
exceed the boiling point of water; however, higher temperatures can be obtained in
those that are operated under pressure. An advantage of the jet machines is that
lower liquor ratios can be used. In a beck, the liquid is stationary and the fabric
moves through it. In a jet however, both the liquid and the fabric move in relation to
each other. This increases the rate of interchange between the liquid and fabric and
speeds up the process. The distinguishing features of jet machines are the venturi
tubes which create the force to circulate fabric, and circulating pumps which cycle
the bath through the venturi tubes. Figures shows schematic diagrams of pressure
and atmospheric jets.
Atmospheric Jet

Schematics of Jet Machines

3. Jig

A Jig or Jigger is a batch machine which handles fabric in open width. It is
a simple machine consisting of let-off and take-up rolls, a trough containing the
processing liquor and guide rolls which allow the fabric to pass from the let-off to the
take-up roll. After all the fabric transfers, the driving mechanism is reversed and the
fabric makes a second pass through the liquor by returning to the original let-off roll.
The cycle can be repeated as many times as it takes to achieve the desired effect.
Figure shows a schematic of a jig.

Schematic of a Jig