In the modern industry, we get to see an increased use of calendar machines as they are widely used in the finishing of textile fabrics and when I come to the production of vinyl plastic sheeting. For coating the materials and manufacturing of paper, the rubber sheeting shows that a calender machine plays an essential part in it. However, these mechanized plain calenders might seem like a new invention. Still, in reality, they were there for quite a long time as they had been quite famous in the middle of the 18th century as it was seen to be used very commonly after they were introduced in England in the 17tth century from Flanders. Two other types of calendars were specially made for embossing and moiréing and various other uses; these were the friction calendar made by William Smith and the Schreiner Calender patented in 1895.
These types of calendars have been made in various forms. They usually range from two roll mixing mill machines to twelve heavy roll rubber mills machinery, mostly mounted vertically over a solid frame in the series pattern. The critical factors over which the machine works are temperature and pressure applied when the material is processed between the rollers. The arrangement of the rollers, their type and their quantity are the factors that are highly useful in determining how the calender would function. In finishing broad-woven fabrics, the results that the calendering would produce are that of ironing the clothes. As the pressure closes the threads and eliminates the creases and flattens to the desired thickness, adding smoothness and some special effects in the form of shine and lustre over the clothes.
However, in the plastic industry, calendering is a method that is being widely used to produce vinyl sheets and plastics. All the ingredients combined along with the resin are blended into a form of a big, hot mass plastic which is passed through the hot rollers that exert the effect of temperature and pressure over. The uniform and even thickness is achieved by the gap on the rollers of the calendar. It is used for the same type of applications in the production of coated fabric and the production of rubber sheeting.
When It comes to calendering in textile, the main factors that are the working principles of these calendaring machines, temperature, force, and moisture, are considered the most critical factors. Achieved by passing the textile substrate between the two heated drums or the rollers vertically attached to a strong frame. However, the speed of rotation, pressure and temperature varies according to the need.
•As the result of the process, there is an effect over the fabric that seems like an effect of ironing which not only makes the fabric crease free but provides a lot more benefits like:
•They also provide special effects making the fabric surface look highly lustrous.
•They also add a smooth, glossy and silky touch to the fabric's surface.
•It adds on to increase the fabric cover factor.
•It can cause a reduction in thickness according to the need, as it Compresses the fabric.
•It can lead to a closing of the threads as it flattens them, which tends to fill up the inter gaps that are left between warp and weft.
•It also reduces the permeability of air as it changes prosperity.
•It also enhances the opacity of the fabric.
•It helps in reducing the yarn slippage.
•Calendering also helps flatten the slabs.
•It helps in the Consolidation of non-woven material.
Calendering is considered an essential process because of its role in textile finishing and giving the surface of the fabric a whole new look. However, various types of calendering exist depending upon the number of rolls present and various other factors. Some common types are: