ABSTRACT
Unlike carding, the combing operation involves the gripping of a small length of fringe lap at all times before it is subjected to the combing operation. Therefore, unlike modern carding where loose fibre flow can be provided as a feed material, in combing it has to be precisely a lap of certain width and weight per yard. The only difference between a lap for a conventional comber and a modern comber lies in its weight per unit length. In short, a modern comber can process thicker and heavier laps.
There are certain expectations from the preparatory sequence used to make a comber lap. The lap has to be uniform, especially across the width. There has to be a minimum level of parallelization and fibre orientation. It should unroll very easily without any problem. More important is to see the direction of the major hooks as are formed in carding. This leads to an even number of preparatory machines to be used to prepare a comber lap.
There are some conventional machines used in making a lap for typical conventional machines. There are modern machinery sequences as well where a modern draw frame and a modern lap-making machine carry out the job. Ideally, there are an even number of machines between card and comber. Hence, the sequence always comes in pairs. Each sequence is characterized by the amount of draft and doubling that it can offer. This is because they decide the level of fibre parallelization and the uniformity of lap.
It may be remembered that there is a certain limit to the draft beyond which it will not only be uneconomical but also it will lead to over-parallelization of the fibres in the lap and it will have a negative effect. As modern combers can process heavier laps, it is important to see that an adequate level of fibre parallelization and lap uniformity must be attained while preparing heavier laps. In this context, especially as regards uniformity, it is equally important to see that the preparatory machines are provided with sophisticated sliver break-stop motions. Apart from saving production of unnecessary soft waste, these maintain the unbroken supply of sliver feed. It is this that leads to more uniform lap production.
