Singeing and Conditioning of yarn

Singeing and Conditioning of yarn

Singeing of yarn:

Both combed and carded spun yarns show many projecting fibers when the yarn s viewed against light. Thus, it is necessary to carry out the process of singeing.

Singeing or gassing is the process which involves burning of protruding or projecting fibers from the surface of the yarn for achieving following mentioned objectives:

• Singeing of yarn makes it more compact and makes the yarn surface lustrous.
• Singeing or gassing removes the bulk of protruding fibers from the surface of the yarn smoother and finer.
• The process of mercerization is more successfully carried out on the singed yarn.

There are different processes for singeing or gassing, the most widely used is the Gas singeing process but it comes with its disadvantages. The modern methods includes the Electrical singeing which has become popular over the years, it has following advantages over the gas singeing:

• The heating is more uniform and it can be controlled.
• The coil has low voltage and hence there is less danger of fire hazards.
• The surrounding area of coil is enclosed with heat resisting materials which prevent any heat loss due to radiation.
• Unlike gas singeing, here discoloration of yarn is less likely to occur.

Following are the defects observed during singeing:

• The yarn gets blackened due to incorrect mixture of air and gas, dirty burners.
• Unbalanced speed of yarn and ill-proportionate heat or produced by the burner flame results in over-singeing,
• Discoloration of yarn is common defects caused by chocked burns, variation in flame intensity and variation in the gas pressure,
• Variation in the intensity of heat produced may also results in formation of strips.

Ventilation in singeing room:

The gassing or singeing room is very important and ventilation is a serious problem and hence it is necessary to provide good ventilation. Proper ventilation ensures removal of burnt gasses and heat produced during process.

There are hoods situated over the machine which carry and burnt gasses and impure hot air provides good solution. The suction fan situated at the end of ducts coming from different machines throws the foul air.

Conditioning of Yarn:  

The conditioning of yarn is the most important after treatment given to single or doubled yarn. However, all the yarns produced in the mill are not given this treatment. The main objects of employing conditioning process are,

• It allows he stresses developed during the twisting operations to relax,
• The liveliness of yarn (snaring tendency developed due to twist) is reduced and it becomes easy to handle yarn in the subsequent weaving preparatory and weaving operations.
• Both the strength and flexibility of the yarn are improved due to moisture absorption. It is carried out by allowing moisture to penetrate in the body of twisted yarn.

A simplest way of conditioning of yarn is to wet it. In the conventional methods and olden days the skips of cops or bobbins were exposed in conditioning cellars for much longer period of time, but five to six days to allow the yarn to absorb the moisture. The process was slow but natural.

Other methods used are Spraying method and Vapour system. In spraying method, the cop is placed on travelling apron and atomized water sprayed. The fine spray helps to penetrate the moisture uniformly.

In vapour methods, the perforated trays are arranged along the circumference of a revolving wheel. This is the fastest method out of all conditioning process and ensures uniform conditioning of the yarn.

Quenching of Yarn:

• The singeing of yarn of yarn involves burning of fibers but sometimes the burnt out fibers do not get completely extinguished immediately, at the yarn leaves the burning zones.
• This can cause continued burning and affect the body of the yarn and hence it is necessary to quench the yarn as soon as it comes out of the burning zone. The quenching of the yarn thus removes any possibility of body of the yarn getting damaged.
• In this process, the yarn in simply made to dip inside a water trough partially filled with water. The quenching of yarn thus removes any possibility of body of the yarn getting damaged.