Degree of combing and its classification:
Table of Contents
The degree of combing is the rate of removal of short fibers, naps, waste, etc. from the drawing slivers through the combing process. The degree of combing is expressed in percent. https://bdfabric.com/why-is-yarn-combing-necessary/
Classification of combing:
Depending on the degree of combing, combing is divided into the following categories:
1. Scratch combing
2. Half combing
3. Ordinary combing
4. Full combing
5. Double combing
1. Scratch combing:
Only 5% of the noils are removed to slightly improve the quality of the yarn. Combing is not done at this stage.
2. Half combing:
In this case maximum of 9%, noil is removed. In this combing process, half of the standard noil is removed.
3. Ordinary combing:
In ordinary combing, the amount of noil varies from 10% to 18%.
4. Full combing:
Full combing usually removes more than 18% of the noils. However in our country (Bangladesh) 15% – 16% full combing is done.
5. Double combing:
In double combing, combing is done twice, 18% for the first time, and 7% for the second time. This type of combing is done to prepare a special type of yarn.
Degree of combing and its classification-Noil:
Combing machine combs to remove short fiber, naps, and waste from fine long fibers. These short fibers are wrapped in a roller with the help of a brush on the back of the cylinder, these are called noils. Usually, the amount of Noil is 15%. However, it is in the range of 5-25%.
Impact on the quantity of Noil:
Reducing the amount of noil depends on the following factors.
1. Quality of the final yarn
2. Short fiber percentage in the raw material
3. Cost of yarn
1. Quality of the final yarn:
In general, the higher the number of noils, the better the quality of the yarn. However, even if the noil is increased at one stage, the quality of the yarn will not be good anymore.
2. Short fiber percentage in the raw material:
The higher the amount of short fiber in the raw material, the higher the amount of noil.
3. Cost of yarn:
Using combing process is to increase production costs. The higher the noil in combing, the higher the price of yarn.
Factors affecting the amount of noil:
The following factors affect the amount of noil.
1. Detaching setting
2. Effect of top comb
3. Effect of lap preparation
4. Effect of the draft
1. Detaching setting:
When the nipper plate is in the front position, the distance between the ripper points of the detaching roller from the nipper plate is called the detaching setting. That is, the greater the distance of the feed plate from the nip point of the detaching roller, the greater the noel, and the shorter the distance, the shorter the noil. Usually 1% change in setting scale results in a 2.5% change in Noil. Almost all combing machines change this setting to change the noil.
2. Effect of top comb:
The greater the distance between the nipper and the top comb, the greater the noil, and the shorter the distance, the less the noil. However, the greater the distance, the better the combing process. Another thing to note is that the better the cylinder comb, the better the combing process.
3. Effect of lap preparation:
Trailing hooks and leading hooks are usually made in the previous process. So in the combing process, it is important to know that lapping with a trailing hook or leading hook is being used in the combing machine. A lap with a trailing hook will have more noil and a lap with a leading hook will have less noil in processing. This is because the needle leading to the cylinder adjusts the hooked fiber. So two-process laps have more leading hooks, which results in better results.
4. Effect of the draft:
The amount of noil is less with the draft that is given to the lap before combing. The higher the pre-comb draft in the same setting, the lower the amount of noil.