Last updated on August 11th, 2023 at 09:33 pm
This method is universally adopted and is suitable for large-scale operations. In this method, many warp yarns as per requirement are assembled in the form of a continuous sheet, sized and then wound onto a weaver’s beam. These operations are supported by auxiliary operations such as separation of ends, measuring warp length, marking into cut lengths and winding the warp of equal length to form the fabric’s warp. All these operations are performed by the slasher or tape sizing machine.
The slasher sizing machines are classified according to the method of drying. Accordingly, there are three types, namely –
- Cylinder drying: Twin and multi-cylinder type.
- Hot air drying.
- Electrical drying.
The first method is based on the principle of conduction and is widely used in industry. Twin cylinders were used for drying of sized warp in the conventional machines. Later multi cylinders have been used and are commonly prevalent nowadays. The second method is based on the principle of convection, and the third method is based on the principle of radiation.
Passage of material through a slasher machine
The general passage of warp through a two-cylinder slasher sizing machine is shown in the following fig:
The yarn from the warper’s beams usually containing about 500-800 warp ends are made to pass into a size box through a guide roller. The warper’s beams, also known as the back beams, are placed in a creel stand. The number of warper beams depends upon the total number of ends required in the cloth or weaver’s beam. The warp from the rear beams passes over and under the successive back beams. The warp sheet emerging from the back beams enters a size box that is kept heated by a constant steam supply through pipes. The warp sheet is made to go under a partially immersed immersion roller and then passes between the size and squeeze roller’s nips. The squeeze roller impregnates the size into the yarn structure and removes external excess size while drags the warp sheet through the paste.
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The wet size yarn then enters the drying zone comprising of either two or multi-cylinders or a hot air chamber. The sized yarn is dried here. The residence time of the sized warp in the drying zone is regulated in such a way as to avoid over-drying. All the cylinders are steam-heated except the last one, which is kept cool by the cold water supply. This is done to cool the warp sheet when it leaves the drying zone.
After leaving the drying zone, the sheet of warp yarns is split into as many sections or layers as there are beams in the creel. This is done using lease rods or split rods. The purpose is to eliminate the stickiness of neighbouring warp threads. The split warp threads are then recombined and then made to pass through an ‘expanding or zig zag’ reed or comb. This comb regulates the width of the warp sheet to the required dimensions. The warp is then made to pass between the nips of a ‘drag roller’ and is finally wound on a beam called ‘weaver or sizers’ beam. In short, the entire slasher machine can be divided into three important zones, namely –
- Creel and size box forming the rear or backside of the machine.
- Drying arrangement forming the middle zone of the machine and
- Front zone or headstock consisting of weaver’s beam, and various controls.