The input of roving frame is silver that comes from draw frame section where only parallel of comber sliver. The roving section reduces the linear density of draw frame silver by drafting. After reducing the linear density the silver is transfer into roving (a thin form of rope). This is the first stage where the twist is inserted for making a yarn in a spinning mill. The output of this section is roving which is wind on a bobbin and this is suitable for the further process. Here in this section describes
In-ring spinning system, conversion of sliver into yarn through a single step has not succeeded since the total draft needed is in the range 300-500 which is very difficult to apply on sliver in a single step and obtain good quality yarn. Sliver cans occupy large space in comparison to the space of one spinning position of ring spinning frame, so there is need to have finer strand wound on smaller packages, which the roving operation satisfy. Sliver is a thick, untwisted strand that will lead to more hairs and fly while converting it directly to yarn when a high draft is applied. In contrary, rovings are finer and twisted so the chances for generation of hairs and fly are less with the roving operation.
Roving frames are also called Speed Frames, Flyer Frames, and most popularly Simplex Machines.
It is an intermediate process in which fibers are converted into low twist lea called roving. The sliver which is taken from draw frame is thicker so it is not suitable for manufacturing of yarn.Its purpose is to prepare input package for next process. This package is to prepare on a small compact package called bobbins. The roving machine is complicated, liable to a fault, causes defect adds to the production costs and deliver the product. In this winding operation that makes us roving frame complex.
There are two main basic reasons for using roving frame
- The roving sliver is thick and untwisted. Because of it hairiness and fly are created. So the draft is needed to reduce the linear density of sliver. The ring drafting arrangement is not capable that it may process the roving sliver to make the yarn.
- Draw frame can represent the worst conceivable mode of transport and presentation of feed material to the ring spinning frame.
Objectives of Roving
The main objective of the roving frame is given below:-
- Attenuation- Drafting the draw frame sliver into roving.
- Twisting-To inserts the twist into the roving.
- Winding-Winding the twisting roving on the bobbin.
- package building
Drafting, Twisting, and Winding
In a roving frame, two drafting frame are used.
- In 4 over 4 drafting system, a total draft should be 13 and in 3 over 3 drafting system, the total draft should not be more than 11.
- 3 over 3 drafting system is better in that case when there is good fiber length
It is a very important factor which produces strength in the roving and twist is inserted with the help of flyer. When flyer rotates, the twist is produced in the sliver. Twist level depends upon flyer speed and delivery speed.
For the winding purpose, we used builder motion.
An important task of the winding are:-
- Shift the cone belt corresponding to increase in the bobbin diameter
- Reverse the direction of movement of bobbin rail at the upper and lower ends of the lift stroke.
Factors Affecting Roving
Critical factors affecting roving strength are given below:-
- The amount of twist and compactness of the roving.
- Linear density and uniformity of the twist.
- CV% of roving.
Defects and its prevention in Roving
Following are the defects and its prevention methods in roving
|1.||Roving tension||Roving tension is directly related to the machine. The roving tension depends upon delivery rate and the difference between flyer speed and bobbin. For preventive action, we should keep the delivery length and the speed difference constant then the tension, in this case, will be ideal.|
|2.||Improper handling of the material||
|3.||Improper piecing in roving||Supervisor should train his workers in a proper way. If end breakage is disturbed then its treatment should be proper. If piecing will not be proper then it will affect the next process.|
|4.||Roving breakage||This problem is caused due to a maintenance problem. Maintenance required machine stoppage but it is against the production. To enhance the quality of the product, the machine maintenance is the chief requirement. For the proper solution of roving breakage, the speed of a machine, trained operator, and proper management should be must otherwise it create severe problems in ring section.|