In yarn manufacturing process; simplex or speed frame is situated after the comber. The sliver which is produced from the comber that is thicker and it is not suitable to feed into the ring frame directly to produce yarn. For this reason, drawn sliver is treated before entering into the ring frame. An intermediate process is done before ring frame. That process is done by simplex or speed frame. This roving frame converted the thick drawn sliver into thin sliver with low twist and produce fine roving which is suitable to produce yarn by feeding into the ring or others. Followings are the principle of roving frame.
Drawn sliver→ Speed frame/Roving frame/Simplex → Roving
Roving → Ring frame → Yarn
In this process drawn sliver is input and fine roving is output. This roving is feed into ring frame for yarn production. It is noted that, simplex is essential for the production of cotton yarn in case of ring spinning by ring spinning system.
Functions of Simplex Frame: Various types of objectives are achieved by the simplex frame like carding or combing action. Followings are the main functions of simplex or roving or speed frame.
- Creeling: Creeling is the first objective of simplex frame arrangement. By the creeling, small amount of draft is applied to the drawn sliver.
- Drafting: Attenuation of drawn sliver to produce required amount of roving by drafting. Thick drawn sliver is converted into thin roving by the drafting system.
- Twisting: Small amount of twist is inserted in the drafted stand of fibers by the twisting. The amount of twist is very low.
- Building: Build the roving on to bobbin such a form which will facilitate unwinding handling and transfer to the next process.
- Winding: Produced or twisted roving is wound on the bobbin by the winding process. This bobbin is feed to the ring frame and this bobbin accelerates the next process. So, it is important.
- Doffing: It is the optional functions of speed frame. Doffing could be done manually or automatically.
So, simplex frame plays an important role in the spinning process. Various types of yarn faults could be appear for the wrong drafting or twisting. For this reason, the operator should be careful during the process. Machine parameters should be set properly for producing specific count yarn.
Proper roving can give better yarn properties. So, we should be care full about the selection of simplex or speed frame or roving frame.
In spinning technology; combing is considered as an additional process. If we want to produce finer yarn then we need to pass combing process. Combed yarn is produce in this method. After carding process combing is done simultaneously to produce combed yarn. Combing process is done to upgrade the quality of the raw materials. Combing is done by the comber.
Objectives of combing process: After carding action, combing is done for produce finer yarn or high count yarn in English counting system. Following objectives are achieved by the combing process.
- To remove short fibers before a pre-selected length.
- Fiber parallelization is improved by the combing action.
- Various types of foreign materials and impurities are removed by the combing action.
- Neps are eliminated by the combing action.
Contribution of combing: Combing action improves different types of fiber properties as well as yarn quality. Followings are the contribution of combing.
- Spinning value (count of yarn) is improved by the combing action.
- Yarn strength is improved by the combing.
- Combing reduces hairiness of the yarn.
- It accelerates the next process.
- Combing reduces imperfection like- neps, thick and thin places of the yarn.
- Better twist distribution is achieved by the combing action.
- Cleaner yarn is achieved by the combing process.
- It improves the smoothness of the yarn.
- Lustrous yarn is achieved by the combing process.
Combed yarn is generally used for produce knitted and woven fabrics. Fineness of the fabric depends on the properties of the yarn. Better quality yarn can give better knitting or weaving efficiency. Most important is that, yarn should have evenness, should be regular in diameter and CV% should be low and quality ration should be high.
Yarn properties also affect the dyeing efficiency. So, yarn should be free from different types of yarn faults.
In winding process; yarns are transferred from one package to another. During winding process; the tension of the yarns should be in controlled, otherwise yarn breakage will be increased for high tension or low tension will hampered the winding operation. So, tensioning device plays an important role in winding.
During the time of winding; to give proper tension to the yarn is the object of a tension device. Tensioning device is used to control the tension of the yarn. If the yarns are irregular or thick or thin place is in yarn then it have chance to break down due to over tension.
Effects of tensioning device: During winding, tension is applied on the yarn stand. Tension may be high or low. Tension has some effects, which is required to know. Followings are the effects of tensioning device.
- Too high tension can damage the yarn. Breakage rate may be greater due to high tension. Too high tension also changes the elongation property.
- Too low tension can lead to unstable or loose package which will not unwind clearly.
- Variation in yarn tension in different parts of wound package can cause undesirable package.
- Tension also effect on manmade filament yarn. It can cause molecular changed in their physical structure. It also effects on the color shading.
- For too high tension, staple or spun yarn may break at thin place.
Requirements of tensioning device: There have different factors which influence the selection of tensioner. Followings are the requirements of tensioning device.
- The tension must be reliable to control uniform tension.
- Tensioning device must be threaded.
- It must neither introduce non magnify tension variation.
- It must not introduce difference in twist.
- It must not be affected by wear.
- It must be easily adjustable.
- It must not be affected by presence of oil or dirt.
- It must not encourage the collection of dirt and lint.
- It must be capable of easy cleaning.
- The operating surfaces must be smooth.
- It must be inexpensive or cheap.
- It must be simple in design or operation.
- It must not be cause of yarn damage.
- Tensioning device should be like that it would not affect the properties of the yarn.
So, design of the tensioning device should be perfect.