Gas Singeing Machine
In this type of singeing machine, the fabric passes over a burning gas flame at such a speed that only the protruding fibres burn and the main body of the fabric is not damaged by the flame. This is the most common type of machine used for singeing fabrics as well yarns.
The main purpose of singeing is to burn the protruding fibres from the yarn and/or fabric surface. In order to burn the protruding fibres, energy must be supplied. The supplied energy must be just enough to burn only the protruding fibres, while keeping the firmly bound fibres in tact. This is achieved by allowing time of contact between the singeing flame and the fabric to practically a fraction of a second. As the temperature of the flame is too high (around 1300°C), any regulation of this temperature is out of the question. However, metering and control of thermal energy of the flame is essential for the safe but effective burning off process.
Main Components of a Gas Singeing Machine
|Fig. Line Diagram of Gas Singeing Machine for Woven Fabrics|
Following are the important gas singeing parameters:
1. Flame intensity
2. Fabric speed
3. Singeing position
4. Distance between flame burner and fabric
5. Flame width
Essential Eonditions for Good GAS Singeing
Following are three essential conditions for good singeing:
1. A flame with high mechanical & thermal energy to quickly burn thermoplastic protruding fibres (e.g. polyester) without any molten beads formation
2. A homogeneous flame with uniform mechanical & thermal energy to result in uniform singeing
3. An optimal flame/fabric contact time to neither result in incomplete not over-singeing
Important Considerations During GAS Singeing
- Make sure that the flame is more bluish (less yellowish) to give the maximum temperature.
- Control and maintain the recommended flame length and angle of contact, depending on the fabric construction, thickness, weight, heat sensitivity, etc.
- Regulate the fabric speed according to the fabric construction/thickness/weight etc.
- Make sure that all the burner nozzles are free from choking. Choking of nozzles may result in the appearance of haziness, patchy appearance or faint lines, which become apparent after dyeing.
- Make sure that the machine is threaded through the machine correctly. Rubbing marks may show up if the fabric is threaded wrongly over defective stationery bars and/or if the fabric rubs against the burners. (As the guide rollers are very close to the burners, any problems due to loose brackets supporting the rollers will guide the fabric to touch the burner block/nozzle). Invariably such defects only show up after dyeing or finishing, at which stage it is difficult to attribute the cause to the singeing machine operation.
- Make sure that the threading is as per specification drawing so that both sides of the fabric are singed. Singeing on only one side of the fabric may result in face to back shade variation after dyeing.
- Make sure that the width of the flame is set to cover just a little more than the fabric width. This will ensure conservation of energy.
- Make sure that the exhaust blowers over the burners are in proper operation. If not, it can lead to redeposition of the burnt out fibres on the fabric causing black specks.
- Ensure appropriate quenching into water/desize bath after singeing. Otherwise, the entrapped smouldering particles may lead to fabric getting burnt (holes).
- Guide rolls next to the flames or the guide rollers on which flame is directed in case of heat-sensitive fabrics should be cooled, generally by cold water circulating through the guide rollers. Otherwise they could become red hot and scorch the fabric.
- Interlinking of stop button/flame switch-off mechanism/ quenching system should be effective to avoid burning of the fabric and any incident of fire.