Thursday, May 17, 2012
This operation is crucial for fabrics made of synthetic fibres (PE, PA, elastomers), for triacetate, and partly for PAC fibres (setting), since it grants excellent dimensional stabilisation and creaseproof properties, maintained till the fabric is exposed (by air blowing) to temperatures exceeding the heat setting one (after being treated with water at a temperature above the second order glass transition temperature, i.e. 80-85°C for acrylics).
Heat setting is carried out on gray fabrics (scarcely applied), on scoured fabrics (frequently applied) and on dyed fabrics (scarcely applied). The process grants excellent dimensional stability and good crease-proof properties. As far as operating conditions are concerned, the fabric must be treated in accurately controlled moisture and temperature conditions.
Heat setting of Some Fibers
Fibre | Min T. °C | Max. T. °C | Time in sec |
Polyester (PE) | 170 | 210 | 15-50 |
Polyamide PA 6.6 | 170 | 210 | 15-40 |
Polyamide PA 6 | 160 | 180 | 15-40 |
Triacetate | 160 | 180 | 15-40 |
Acrylic (PAC) | 160 | 180-200 | 15-40 |
Elastomers | 170 | 180-200 | 15-40 |
Stages of Heat Setting
Heat-setting can be carried out at three different stages in a processing sequence i.e. in grey condition; after scouring; and after dyeing. The stage of heat-setting depends on extent of contaminations and types of fibres or yams present in the fabric. Heat setting after dyeing could lead to the sublimation of disperse dyes (if not accurately selected).
Stenter Machine
Stenters are widely used for stretching, drying, heat-setting and finishing of Fabrics. The stenter frame is usually 80-100 feet long and 70-100 inches wide. The speed ranges from 10-45 m/min with a maximum setting time in the setting zone 30 sec at temperature ranging from 175 to 250~ depending upon the thickness and type of the material.
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| Stenter machine in heat setting |
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