Fabric quality consists of inherent quality and appearance quality of fabrics. With the growing internationalization and brand‑awareness of garment enterprises, the market demand for defect‑free yarn and defect‑free fabric has pushed textile enterprises to impose increasingly stringent requirements on the length and size of yarn defects on cotton fabrics. Accordingly, 100‑kilometer yarn defect testing, data analysis and control have gained widespread attention in cotton yarn production. In particular, advances in electronic yarn clearer technology for automatic winders and improved splice quality have provided effective guarantees for reducing yarn defects in cotton yarn.
Method 1 Strengthen Equipment Maintenance and Parameter Setting
From the perspective of root causes, Class A2 yarn defects are raw‑material‑related defects, which appear as numerous short and tiny defects distributed across fabric surfaces. Such defects are generally caused by high short‑fiber content, low fiber maturity and high defect content in raw materials. To reduce fine yarn defects in cotton yarn, strict cotton blending standards shall be formulated for raw materials, and the N and S parameters of yarn clearers on the winding process shall be continuously revised.
During spinning, immature cotton fibers tend to form abundant hooks, generating numerous fine yarn defects. Therefore, it is essential to control the quality of raw cotton. When establishing raw‑cotton quality control standards, consideration shall be given not only to the quality requirements for fine yarn defect quantity for different cotton yarn counts, but also to the quality requirements imposed by weaving and dyeing processes on cotton yarn. Proper cotton blending requires control over blending grade, fiber length and fineness, as well as appropriate limits on immature fiber content and short‑fiber content.
Due to the presence of short fibers in cotton, high‑speed operation of spinning equipment turns large quantities of short fibers into fly and dust. These fly and dust adhere to spinning components or yarn paths and induce various yarn defects in finished cotton yarn. Therefore, to reduce fly‑induced slub‑type yarn defects, standardized routines for operational cleaning, institutionalized equipment maintenance and wiping, and systematic inspection of key components must be implemented item‑by‑item with enhanced record‑keeping and checking. This ensures no fiber accumulation, fiber hooking, fiber wrapping, fiber sticking on machinery of each process and avoids damage to sliver structure.
Winding is the final quality‑control process in spinning and also the initial quality‑control process for weaving. The electronic yarn clearer serves as a critical tool for yarn defect control. Apart from removing yarn defects, the yarn defect detector also plays a vital role in maintaining the operating efficiency of automatic winders. The setting of electronic yarn clearer parameters shall be relaxed or tightened according to fabric requirements. For high‑grade fabrics, the electronic yarn clearer mainly removes part of neps (N) and short thick places (S), which brings relatively heavy defect‑removal workload. In actual production, the N and S parameters of yarn clearers shall be continuously adjusted, and process suitability can be verified by rewinding packages. Through these measures, Class A2 yarn defects can be significantly reduced.
Method 2 Set Electronic Yarn‑Clearing Process Rationally to Reduce Yarn Defects and Improve Yarn Quality
With continuous development of electronic technology, electronic yarn clearers have become increasingly powerful. However, blind pursuit of minimal yarn defects at the cost of production efficiency will result in excessive cuts. Frequent cutting leads to high false‑cut rates: minor yarn defects are reduced while harmful large‑size defects remain hard to eliminate, splice joints increase, winding efficiency drops markedly and production costs rise. Consequently, reasonable electronic yarn‑clearing parameters shall balance quality and efficiency.
When setting electronic yarn‑clearing parameters, enterprises may establish initial parameters based on 100‑kilometer yarn defect test results of ring‑spun cops, then optimize parameters according to 100‑kilometer yarn defect data of wound packages. Alternatively, preliminary parameters can be set first followed by yarn defect inspection on one hundred cops. In our test, packages wound from 200 ring‑spun cops were divided equally into two groups. Yarn rewinding was performed successively with loosened and tightened electronic yarn‑clearing parameters on the same machine and spindle position, and blank‑cut rates were calculated. If initial parameters produce many blank cuts and numerous minor removed defects, while loosened parameters can cut more large defects, the original parameters are over‑tight. If initial parameters show few blank cuts and many removed large defects with few minor defects, and tightened parameters greatly increase minor removed defects: the original parameters can be retained if they meet customer requirements (low quality requirements); otherwise, double electronic clearing shall be considered.
In summary, electronic yarn‑clearing parameters shall match yarn inherent properties and customer requirements — excess is as bad as deficiency. Emphasis shall be placed on analyzing yarn defect types and root causes. Effective countermeasures shall be adopted from perspectives of process, equipment, operation, temperature and humidity to cut yarn defects and boost yarn quality. Statistical data from electronic yarn clearers shall be combined with physical sample evaluation to guide quality control of upstream processes. Over‑reliance on electronic yarn clearers for quality improvement is inadvisable.
Method 3 Improve Spinning Machinery Condition Maintenance to Cut Spindle‑Belt‑Slippage Twist‑Related Yarn Defects by 60%
To mitigate mechanical twist‑related yarn defects, we conducted yarn twist tests under faulty conditions for spindles, spindle belts, tension discs and wharves. Five key control items were selected for root‑cause analysis according to their impact magnitude.
- Spindle belt caught on tension‑disc shaft or guard hook. Primary causes: doffers hook the spindle belt while cleaning tension discs; insufficient lubrication causes tension‑disc vibration or bearing seizure, resulting in spindle‑belt slipping off the spindle‑belt pulley.
- Severe spindle‑belt deviation: spindle belt runs out of the spindle pulley. Main cause: doffers pull and hook the spindle belt when cleaning spindle pulleys with brushes. The diameter at the deviated belt position is smaller than that of the spindle pulley, producing over‑twisted yarn; conversely, under‑twisted yarn is generated.
- Pressurization failure. The spindle‑belt tension press arm of JWF1516 ring spinning frame adopts a lever‑geared, open‑hung weight structure. Compared with old‑model frames with screw‑locked weights, it features easier pressure adjustment and maintenance, yet brings higher risks of weight dropping and wrong hooking position.
- Wharf locking failure. Wharves and locking sleeves for fixing wharves on JWF1516 ring spinning frame are plastic parts prone to deformation, aging and brittleness, which impair locking elasticity, increase nut loosening risks. Complete nut disengagement leads to wharf locking failure.
- Spindle sinking. Damaged spindle support bearings or worn spindle tips cause spindle sinking, resulting in unstable spindle operation and oscillation, fluctuating spindle speed and reduced yarn twist.
Based on root‑cause analysis, the following countermeasures were implemented: strengthen pre‑job training for new operators to raise responsibility awareness and ensure correct operation procedures; enhance maintenance to guarantee good machinery condition; reinforce inspection and tracking; appropriately expand the scope and quantity of twist tests; perform twist tests on low‑tenacity yarn identified in lab tests and alarm‑triggered cops rejected by automatic winders; track down root causes once twist‑related defects are detected and eliminate faulty machinery conditions; strengthen work‑quality inspection for night‑shift maintenance workers and doffers; record and rectify all faulty machinery conditions.
These measures delivered remarkable results. Statistically, monthly average faulty machinery items decreased by 61.11%, and rectification rate rose from 77.81% to 100%, with twist‑related yarn defects substantially reduced.
Post time: Aug-11-2026