This document discusses a stenter machine, which is used in textile processing. It has three main units: a padder to apply finishing agents uniformly, weft-straightening devices, and control equipment. The stenter machine is used for processes like equalizing fabric skew and bow, controlling printed designs, setting fabric width, applying finishing chemicals, and drying. It works by conveying fabric between two endless chains through heated compartments to dry and set the fabric. Key aspects of operation include temperature uniformity and control, and devices to straighten the weft of the fabric.
3. Main Units
A padder to uniformly wet-out fabrics and apply
finishing agents,
Weft-straightening devices
and control equipment
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4. Uses
The stenter is a continuous types of machine and can
be used before or after dyeing/printing.
The stenter frame used for following processes.
1. Equalizing(skew and bow control)
2. Printed design control
3. Fabric width setting
4. Application of finishing chemicals
5. Drying
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8. Process Description
The selvedges are held by two endless chains typically
40 to 60 metres in length and the fabric is conveyed
through a series of heated compartments or bays. Hot
air is directed onto the fabric equally from above and
below. The selvedges are held either on pins about 5
mm long mounted in base plates or by clips that grip
the selvedges between smooth surfaces. Lubrication of
the chain is important and this takes place
automatically during running. The lubricant must be
completely stable during continuous high-temperature
operation.
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9. Some features
Stenter speeds range from only 10 m/min for heavyweight
furnishings up to 100 m/min for lightweight dressgoods.
Overfeed is frequently necessary to compensate for warp way
stretch in previous processing and to minimise shrinkage in washing
and dry-cleaning.
The speed of the fabric through the stenter is controlled by the
motion of the pin chain, but the fabric entry can be adjusted
independently by the entry rollers.
Temperature uniformity over the entire area of fabric is ensured
Too low temperatures do not allow a good setting while too high
temperatures and too long setting times cause yellowing (PA and
elastic fibres), stiff hand (acrylics), and loss of elasticity (elastic
fibres).
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10. The setting temperature used is above Tg.
In heat setting, inter-chain bonds, such as
hydrogen and dipole bonds, break. This
allows the molecular chains to move and
adopt new, stress-free positions. New
intermolecular bonds then form with the
fabric in a relaxed condition at the setting
temperature. After cooling, the polymer
molecules in the filaments become frozen in
place. The new bonds are stable up to the
heat setting temperature. The reorganized
internal polymer structure, and the
material’s dimensions, will be stable.
Heat setting
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18. Mahlo or Bianco Location
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19. 1. Actual weft
configuration
2. Actual
distortion (in%)
3. 60min trend
diagrams
(skew and bow)
Controling Monitor
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