The commonly used, time-tested spinning technique, ring spinning is one of oldest machine oriented spinning techniques used for staple fiber spinning. The staple fiber such as cotton and wool has to go through a series of processes until reaching the finished product or the yarn package.
The ring spinning system is the oldest spinning system that remains dominant because of the high-quality yarns it produces. Ring spinning has various advantages besides disadvantages.It is the most flexible system from the viewpoints of fibers which can be used and the extent of the yarn counts which can be produced.
Before talking about Ring Spinning Pros and Cons, let's understand what the Ring Spinning Process is with the Yarn Fair.
Ring Spinning Process
l Roving bobbins are creeled in appropriate holders
l Guide rods leave the roving into the drafting arrangements
l Drafting arrangements attenuate the roving to the final count
l The drafting arrangements are inclined at an angle of 45 degrees to 60 degrees.
l Upon leaving the front rollers the fiber strand is twisted to impart strength
l Each rotation of the spindle imparts one twist to the strand
l The twist is generated by the spindle which is rotating at high speed
l The directions of the twist are either “S” or “Z”
l This completes the spinning of the yarn
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l The amount of twist inserted in the yarn is controlled by the front roll or the delivery speed and traveler rational speed
l Traveler Speed Formula
l In practice, spindle speed(n spindle) is used instead of traveler speed in the above equation, the spindle speed is slightly higher than traveler speed
l Yarn Winding is performed simultaneously with Twisting
l The difference in the speed between traveler and spindle causes the yarn to wind on the package
l The size of the yarn package is limited by the ring diameter, which has to be small to increase the spindle rotation at the same traveler speed
l The draft is the ration between the delivery speed and the feeding speed.
l The twist is the ratio between spindle speed and the delivery speed
l Winding speed is directly proportional to the delivery speed
l Contraction occurs in yarn by increasing twists
The metal ring is the origin of the name of the ring spinning machine. The twist creates friction between the fibers by which the strength of the fiber mass increases. In this state, the fiber mass is now called yarn. The yarn is wound on to a bobbin attached to the spindle. The speed of the spindles amounts to 10,000 to 14,000 r/min for wool and about 18,000 to 25,000 r/min for cotton. Thus one meter of yarn contains between 300 and 2,000 twists. The weighting arm is required to allow different loads to be set on the top rollers. Normally this is achieved by helical springs which can be adjusted mechanically in steps.
Also, the distances between the rollers have to be adjustable. The distance has to be larger than the length of the longest fibers to avoid the situation where single fibers are torn between the clamping points of top rollers and bottom cylinders.
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Advantages of Ring Spinning
The Ring Spinning System allows various types and lengths of fibers (natural, man-made) to spin on a wide count range from 6 tex to 118 tex.
whereas this range is between 17 and 118 tex in rotor spinning. By combing option, the high quality combed yarns which are smoother, brighter and more compact can be produced using the ring system. On the other hand, the ring spinning system has two main problems. The first is low production speed because of frictional contact of ring and traveler, and the yarn tension caused, and the second is high energy consumption that causes high production costs.
Following are the advantages of Ring Spinning Process:
l Production of high strength yarns.
l The spinning of fine count yarns.
l Proper for special yarns.
l It is universally applicable (any material can be spun).
l The know-how for the operation of a machine is well established accessible to everyone.
l It is flexible as regards quantities (blend and lot size).
l Since the speeds in drawing section are best controlled, yarn evenness is excellent. But if short fibers are too much, yarn unevenness occurs.
l Fine yarns can be produced as compared to the open-end system
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Disadvantages of Ring Spinning
Following are the disadvantages of choosing Ring Spinning Process:
l Process stages are more numerous. Roving stage exists as an extra process compared to the other systems.
l Yarn breakages are more numerous as a result of ring traveler friction and yarn air friction. Interruptions, broken ends and piecing up problems exist because of the yarn breakages.
l The high speed of the traveler damages the fibers.
l The capacity of the cops is limited.
l Energy cost is very high.
l Low production rate.
l New spinning processes have difficulty in gaining widespread acceptance. Owing to their individual limitations, the new spinning processes are confined to restricted sectors of the market.
l The ring frame can only survive in the longer term if further success is achieved in automation of the ring spinning process. Also, spinning costs must be markedly reduced since this machine is significant cost factor in a spinning mill.
l The cost structure in ring spinning mill is shown in the graph.
Source: Textile School
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Various significant aspects of brassiere manufacturing are covered, e.g. bra design, molding technology, and manufacturing automation. Bra design is substantial to brand product development while innovative molding technology is the key to signature types of bras like a sew-free bra, seamless bra, and one-piece bra. Automation has been a global trend in manufacturing as it reduces the labor cost and, on the other hand, enhances the consistency in product quality.
In this article organized by the underwear fair, various significant aspects of brassiere manufacturing are covered, e.g. bra design, molding technology, and manufacturing automation. Bra design is substantial to brand product development while innovative molding technology is the key to signature types of bras like a sew-free bra, seamless bra, and one-piece bra. Automation has been a global trend in manufacturing as it reduces the labor cost and, on the other hand, enhances the consistency in product quality.
The raw material used for Bra production
The raw materials gathered for the production of brassieres vary tremendously depending on the product. Some are all cotton, some are all polyester, some are combinations of natural and synthetics, and so forth. Most brassieres include an elastic material of some sort on the back panel that allows some expansion and movement of back muscles. Spandex, a modern synthetic fiber extensively processed from Malaysian tree sap, must be processed prior to the assembling of the brassiere because it is, in some products, the most important material in the brassiere. A closure of some sort (most often metal hooks and eyes) must be included on the brassiere unless it is an elastic sports brassiere which can be put on over the head. Cups, padding, and straps vary not only from manufacturer to manufacturer but by style.
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The Manufacturing Process
The methods for constructing brassieres vary from one company to the next. It is a product that is still pieced out in some plants, which means that the sewing work that connects all the components are contracted out of the plant to smaller sewing operators for job work. In addition, materials utilized in the construction of the brassiere affects the manufacturing method. For example, if an undergarment company utilizes spandex within the product, they may manufacture the material on premises. If a company uses cotton, it may be supplied from a manufacturer who makes the material based on their specifications.
Cutting out the components
The components of the brassiere—the cup top and bottom (if seamed), the straps, and the central, side and back panels—must be cut out according to the pattern specifications residing in the computerized specifications. Many layers of fabric are cut out at a time using either a bandsaw-like shearing device or a more contemporary computer-controlled laser. The cups, panels, and straps are cut; kept together in stacks via style; and sent out to various locations to be sewn.
Sewing
The stacks may be sent to different parts of the factory or even off premises to piece workers who assemble the brassieres using industrial grade sewing machines. However, large operations send the pieces The manufacture of brassieres involves first cutting many layers of fabric at one time using either a bandsaw-like shearing device or a more contemporary computer-controlled laser. Once cut, the pattern pieces are assembled at the factory by workers, off-site by piece workers, or by automated machinery. Hooks and eyes are both sewn in by machine and heat processed or ironed into the two halves of the back panel.Cups might be sewn onto a side panel, the parts move along and another piece is sewn on, etc. In larger facilities, humans rarely sew anything onto the brassiere unless it is a peculiar or unusual design.
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Closures and labels
The brassiere, assembled a bit at a time as it moves through the machinery, is ready for the closures. Coated metal hooks and eyes are both sewn in by machine and heat processed or ironed into the two halves of the back panel. The label is usually machine-stitched into the back or side panel as well at this time.
Packaging
The completed brassieres are sent (either transported in a bin or on a line) to another location and sorted by style and folded (either by hand or machine depending on the size of the operation). Boxes into which many brassieres come arrive at the manufacturer completely flat. Machines must crease and fold the packages that are fed into the machine and a rectangular box is created. A worker called a picker puts a brassiere into the box, the box is closed, and then sent down a chute. A laser reads that the box is fully packed and ready to go to the holding area, awaiting transportation to the wholesaler.
Quality Control
Quality is controlled in all phases of the design and manufacture of the brassiere. First, experienced designers and design engineers understand the requirements of the wearer as well as the marketers and design with activities and cleaning requirements in mind. Second, a very important part is procuring fabrics and components (underwire, hooks, and eyes, or buckles) that are durable. Testing of materials includes assessing shrink-resistance, color-fastness, and durability, shape-retention, stretch, manufacturing stability, and comfort. Companies work with suppliers in order to acquire new materials that provide service as well as value. In fact, some manufacturers have developed their own fabrics or underwire because all other similar support materials on the market were inferior. Third, prototypes are extensively examined by many members of the company and problems are discovered and solved when many are involved in the assessment of new products. An essential part of this is when the prototype moves from a single example to early manufacturing. Those involved in the manufacturing assist in solving the problems that can occur in the initial stages of manufacturing.
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Finally, manufacturers must offer consumers brassieres that fit well. In prototyping and in manufacturing, the brassieres are inspected and expected to be within 0.125 in (0.3175 cm) of the desired measurements (one French company requires that the brassiere must not deviate from the standard pattern more than 1 mm[0.0394 in]). If not, the brassiere is rejected as an inferior or second.
Source: Textile School
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