Why singe?
Singeing is to quickly pass the fabric through a flame or rub it against a red-hot metal surface. Burn off the fluff on the surface of the fabric to make the surface smooth to prevent defects in subsequent processing.
The impact of the presence of fluff on the fabric:
It is difficult to recycle the roller mercerizing liquid when stained with dust and has poor gloss when printing. Pilling and pilling of dragging pulp and dragging knife affect pattern clarity
How to singe?
Singeing is a process in which the fabric is quickly passed through the flame of the singeing machine or rubbed against the red-hot metal surface in an open-width state to remove the fluff on the surface of the fabric and obtain a smooth surface. process. At this time, the fluff on the cloth surface is close to the flame and is loose, so it can heat up and burn quickly. The fabric itself is relatively tight, thick, and far away from the flame, so it heats up slowly. It has already left the flame or the red-hot metal surface before the temperature reaches the ignition point. Therefore, the principle of different heating rates between the cloth body and the fluff is used to achieve It only burns away the fluff on the surface of the fabric without damaging the purpose of the fabric.
During singeing, the singeing temperatures of different fiber materials are also different, so it is necessary to understand the thermal properties of different fiber materials.
Thermal properties:
Cotton fiber: thermal cracking occurs at 350℃~370℃
Starts burning at 400℃
Polyester fiber: 230~240℃ soft switching point
250~260℃ melting point
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Combustion starts at 485℃
Principle analysis: using the temperature difference between the fluff and the fabric body. The fluff is small in size and heats up quickly, while the fabric in large volume heats up slowly, so the fluff is easy to be burned during singeing, while the fabric is difficult to burn and does little damage to the cloth.
Key points: High temperature (conducive to singeing) and fast (protecting the fabric) are required to ensure that only the fluff is burned off without affecting the fabric body.
Notes:
The temperature is too low (under-heated) and not burned cleanly. The fluff will be ball-shaped and color spots will appear during dyeing. . If the temperature is too high or the speed is too slow (over-burning), the fabric will shrink thermally, causing wrinkles and hand-induced phenomena, and the width will shrink. If the fabric falling temperature is lower than 50℃, take measures such as blowing cold air or installing a cold water roller on the fire control. In addition, in order to eliminate sparks on the fabric surface, the fabric should enter the fire extinguishing tank (built-in hot water or desizing fluid), otherwise it will appear on the fabric surface. holes.
What are the singeing machines? There are two ways of singeing, namely contact singeing and non-contact singeing. Contact singeing machines include copper plate singeing machines, cylinder singeing machines, and electric hot plate singeing machines. The non-contact singeing machine is a gas singeing machine. At present, gas singeing machines are widely used, copper plate and cylinder singeing machines are not widely used, and electric hot plate singeing machines have been basically eliminated.
1. Gas singeing machine
Infeed → Brush → Singeing → soaking in juice to extinguish fire → dropping cloth
Schematic diagram of gas singeing machine
2. Copper plate singeing machine
The copper plate singeing machine uses fabric to quickly rub against the surface of a red-hot copper plate to burn off the fluff on the surface of the fabric. Features: During singeing, the fabric is in direct contact with the copper plate, and the impurity removal effect is better than that of the gas singeing machine. It is used Singing of thick fabrics and low-grade cotton fabrics.
3. Cylindrical singeing machine
During singeing, The fabric quickly passes through the continuously rotating red-hot cylinder to burn off the fluff on the surface of the fabric. The rotation of the cylinder is opposite to the forward direction of the fabric
Comparison of several singeing machines
Notes
1) In order to improve the singeing efficiency, the fabric should be dried evenly before singeing. Keep the moisture content below 5%, but if the drying is uneven or the drying effect is not good, it will affect the singeing effect.
2) Except for thin and jacquard fabrics, the hair should be brushed before singeing.
3) The brushing roller should be cleaned regularly to prevent yarn ends from clinging to the surface and affecting the brushing effect.
4) When the fabric is put into the machine, it should not be skewed, curled, or wrinkled to prevent uneven singeing defects.
5) When using a gas singeing machine to singe, you should always check the flame color. If the flame jumps and shakes or the color is abnormal, it means that the ratio of air and flammable gas is improper. Both should be adjusted. ratio.
6) Frequently check the quality of the fabric, mainly the singeing effect of the fabric; also pay attention to local or continuous defects, such as uneven singeing, holes, etc. For polyester blended fabrics, more attention should be paid to the fabric falling temperature, hand feel and fabric shrinkage. If the singeing is excessive, it will generally feel hard, the fabric will shrink too much, and the breaking strength, especially the tearing strength, will decrease significantly.
What are the factors that affect singeing?
Fiber properties: Cotton fabrics can be singed in the first step, while chemical fiber fabrics can also be arranged after dyeing.
Moisture content: Too high will causeThe singeing effect is reduced, and uneven moisture content will also affect the singeing effect.
Hairiness status: The hairiness is loose and the straight force ratio is tight. It is easier to singe. Therefore, the singeing machine is equipped with a bristle box to brush up the hair to facilitate singeing.
Some slurries will become hard due to singeing. The singeing should be done after the desizing process, especially for chemical fiber fabrics.
How to evaluate the quality of singeing?
The measurement standard of singeing quality is currently mainly judged by the degree of fluff removal, but it must be ensured that the fabric is not damaged (no damage, minimal loss of fabric strength). The specific method is to place the singed fabric under better light, and refer to the standards for visual rating:
The singeing quality of general fabrics should reach level 3~4, those with high quality requirements should reach level 4 or above, and thin fabrics should reach level 3.
How to solve the defects caused by singeing?
1. The singeing is not clean
1. The distance between the inner flame and the cloth is too large, and the temperature of the copper plate or cylinder is not enough
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Solution: adjust the height of the inner flame or increase the temperature of the copper plate and cylinder
2. Driving too fast
Solution: slow down
3. The drying and brushing devices are not functioning
Solution: Clean the brush and emery roller, and adjust the contact surface with the fabric to improve the drying effect
2. Excessive singeing (burning, hardening or melting of the polyester, or excessive shrinkage of the fabric)
1. The temperature during singeing is too high or the fabric is thin and there are many fire openings
Solution: adjust the flame temperature and adjust the number of singeing surfaces
2. When polyester and vinylon blended fabrics are singed, the fabric temperature is too high
Solution : Strengthen the blowing cooling between the fire ports
3. The vehicle speed is too slow
Solution: Speed up the vehicle
3. Uneven singeing (singing strips or uneven left and right)
1. The burner is clogged or deformed, and the surface of the copper plate and cylinder is uneven
Solution: clear the burner or correct the gap in the burner, or plan it. Iron plates on both sides of the burner
2. The temperature of the copper plate and the two ends of the cylinder is inconsistent
Solution: File the copper plate or flatten the cylinder
3. Cloth wrinkles
Solution: Improve the operation, adjust the fabric feeding tension guide roller, and keep the edge suction device flexible
4. Holes or chipped edges in singeing
1. The trailing yarn, edge yarn, neps, etc. are extinguished promptly after burning
Solution: shorten the distance between the fire outlet and fire extinguishing
2. Sparks fell on the cloth and were not extinguished in time
Solution: Replace the atomizing nozzle or increase the vaporization temperature. If the gasoline vaporizes poorly, oil droplets will spray onto the cloth surface
3. The speed is too slow
Solution: speed up the car</p
