ABSTRACT
A normal combing operation can improve the quality of the product to a certain extent. If one wants to achieve something beyond this, the combing operation has to be repeated once again. The process is called ‘double combing’. Though superficially, things look simple, repeating the process requires utmost care. Especially handling the material of a first combing is a very tricky job. This is because the sliver is very soft and weak due to parallelised orientation of the fibres. Therefore as is required, making a worthwhile lap requires extra skill. In the second combing the waste extracted is just 7–8%. Together, therefore, the total waste extracted reaches the range of 24–30%. The improvement sought here is not the yarn strength but the yarn appearance.
The combing of blends is another issue. Normally, blends are not combed. This is because the blends are done for improving the contribution of each component in the final mixture. When the blends with heterogeneous fibre length and fineness are tried, the results are never encouraging. This is because the comber noil has far more proportion of shorter fibre component.
It is often a matter of interest to judge the performance of the comber. Apart from popular and easy methods of measuring the change in nep level or improvement in mean length, not much was thought to be markedly achieved showing the actual performance. People have tried to devise methods of actually measuring the fractionating power of a comber. They carried out an exercise of evaluating the performance by finding in each group length group the reduction in short fibres. Even then, these methods and their actual carrying out are time-consuming and tedious.
It is known that the hooks are formed in carding. The efforts were directed to measure the hook content. As the hooks are sensitive to the direction in which they were delivered by the card, the method was able to give a good measure of hook content. This has been very useful in finding the effectiveness of the drafting process and related repercussions.
