Hair Severity - An excellent process health indicator
by V.Srinivasan1 & S.Balamurugan2, Premier Evolvics Pvt Ltd, India
This is the third of the four series article on Hair Severity - A new yarn hairiness parameter introduced by Premier

1Mr. V Srinivasan is a B.Tech (Electronics and Communication) and has been with Premier Evolvics for the last twenty years. As the head of R&D for lab products, he is responsible for the conceptualization, design and ongoing technical support for Premier Lab Products. He is an active member of the ITMF spinners committee and has presented several papers at international forum like Bremen Fibre Conference. He also has 3 patents in his name.

2Mr.S.Balamurugan is a Textile Technologist with more than 18 years of experience. He has worked with leading manufacturers & mills like Super Sales, Precot-Hindupur and Isparta Textiles –Turkey. At Premier Evolvics he has contributed extensively towards development of the Hair Severity parameter. His key area of excellence includes quality and maintenance in spinning.
 

Hair Severity: True Hairiness

Hairiness is one of the critical yarn properties influencing the process as well as the fabric appearance. The influence of fibre properties and other conditions in spinning process such as the Machine speed, Drafting arrangement, Atmospheric conditions and Ring/Traveller combination is clearly visible in yarn hairiness characteristics. In the immediate post spinning process- higher winding speed, level of winding tension and the selection of appropriate wax has a high impact on yarn hairiness. Hairiness is also critical in the subsequent processes like Knitting, Warping and Weaving. Distribution of hair length is one of the most important characteristics of the yarn which is a decisive factor for several end uses. Analysis of disturbing long length hairs helps to identify whether a process is effective or not. It also helps to fine tune and assess the Compact spun yarn process where reduction in the hairiness values is experienced, especially in the longer hairs.

Hairiness Index is not the true representation of hairs. Hair count from 3 – 10mm involves a complex procedure to analyze the measurement. Since the application of both the above parameters calls for a comprehensive solution, Premier has introduced a new parameter “Hair Severity” which replaces the conventional Hairiness measurements. Hair Severity represents the severity of the long length hairs. Hair Severity (HS) is measured by the Premier iQ QualiCenter.

Hair Severity provides significant information on the selection of critical process parameters as well as the Life of machine components. Controlled studies have been conducted in Spinning and Winding to identify the factors influencing HS. 

v     What are the Spinning process parameters which are related with yarn Hair severity values?

v     How is the component life decided by monitoring the HS values? 

v     How to optimize machine parameters in winding with respect to HS?

To understand the above factors which influence the Hair Severity, studies have been conducted across various cotton counts. The following parameters were considered in Ring frame and Automatic winding machine for studies:

v     Optimization of Twist level in Ring spinning

v     Optimization of Spacer size

v     Ring life

v     Ring Traveller selection

v     Tension level in Auto winder

v     Wax selection

HS provides useful information for critical process parameters in Spinning

Hair Severity (HS) vs. Ring Frame Twist level
 Higher the Twist level, Lower the Hair Severity

Studies reveal a clear reduction in HS values with increase in Twist level. This is mainly due to the short spinning triangle and effective twisting of fibres into yarn. In Hosiery yarn, lower twist level is used to have softer feel, which results in High hairiness values. Conventional Hairiness measurement (Hi) doesn’t reflect the variation in Twist level, but HS provides the correct information. By monitoring HS, Twist level can be optimized for better Hairiness results. This is supplemented by studies conducted for various count and material.

It is clear from figure 1. that, higher Twist level leads to low HS. In 30s CW for a Twist level of 17.74, Hairiness Index is 5.18; when the Twist level is increased from 17.74 to 19.08, Hairiness Index (Hi) decreased to 4.98. As can be observed, the Hi does not reflect the true yarn Hairiness. The HS, as illustrated in Table.1 reflects true yarn hairiness.

Hair Severity (HS) vs. Ring Frame spacer size 

Spacer size plays a significant role in the reduction of Hair Severity. In general there is a tendency to use thinner spacers in order to reduce the Imperfection and Unevenness level. Any smaller spacer used beyond a limit increases the Hair Severity due to the excessive force applied on fibre fleece by the drafting rollers. As shown in the table: 2, an optimum spacer delivers the yarn with the least Hair Severity.

Hair Severity (HS) vs. Ring Life

In a spinning mill, components replacement plays a major role in the regular maintenance activity. The cost involved in replacement of the accessories and components contributes towards maintenance cost/spindle. Yarn Quality is a major deciding factor in the replacement of the components.

In this context, yarn Hairiness is a critical parameter which is considered for components replacement especially Rings in the Ring frame. Worn out Ring is one of the major causes for increase in hairiness and variation in hairiness. When the degree of wear is increased beyond a certain limit, yarn produced will be of high hairiness resulting in an inferior end product. With the conventional measurement of hairiness, degree of wear is not reflected in the results. Whereas Hair Severity truly indicates the quality of Rings. Hence HS can be used as a deciding factor in optimizing the life of Rings towards better yarn quality.

It can be identified from the above graph that HS has a good relation with Ring life i.e. HS shows a 60% increase in values between 2 years and 3.5 years Ring life. But the Hairiness Index shows only an increase of 4% in values as illustrated in Table: 3.

Hair Severity (HS) vs. Ring Traveller selection

Optimizing travellers for new counts call for better understanding of the yarn quality and productivity requirements. While lighter traveller results in low end breaks and high Hairiness, heavier traveller results in Lower hairiness but with more end breaks. Usually while selecting the traveller, the profile, finish, weight and height of the traveller is considered. By using HS the above selection process is made quicker and reliable. Several studies have revealed that HS has a better relation with selection of travellers when compared with Hairiness Index. An example is shown in Table: 4.

In figure.4, HS shows an increase of almost 50% between the two traveller profiles, whereas it is not reflected in the Hairiness index.

Hair Severity (HS) vs. Tension level in Auto winder

Optimization of winding tension is important to achiever better yarn and package quality. While doing so, Hairiness increase can be controlled to a minimum. Improper yarn tension can give rise to Hairiness increase up to 100%. It is proven that long length Hairs increase drastically with increase in winding tension. This is well explained in table: 5, while yarn tension is increased, HS shows significant rise which describes True hairiness.

Hair Severity (HS) vs. Wax selection at Auto winder

It is a regular practice in mills to use wax during winding for Hosiery yarns to reduce Hairiness as well as to have better running in the next process. By selecting appropriate wax quality and controlling the wax pickup, variation in hairiness can reduced to a minimum. As shown in the below table: 6, Hairiness Index doesn’t reflect the quality of wax used, whereas HS provides the correct information. Hence HS can be used as an effective tool for selection of appropriate wax to optimize yarn quality as well as waxing cost.

Conclusion

It is clearly evident from the above studies that Hair severity helps optimize process parameters and decide life of critical accessories in Spinning and Winding which enables Spinners to achieve better yarn Quality and Productivity with minimum cost.

More information on HS

To highlight the usefulness of Hair Severity in further processes like Knitting and Weaving, several studies have been conducted. Studies reveal useful information for knitters and weavers in selection of appropriate yarn to keep their quality, productivity and cost levels within standards.

For a detailed understanding of the same, write to Premier at mail@premier-1.com for a copy of the Premier Intelligence Book on Hair Severity.