Mixing Quality Cost #1

 

Mixing Quality Cost

• Cotton cost: Single largest component in total yarn cost (60-70%).
• Cotton cost can be controlled by efficient formulation of mixing for various counts, yarns being spun.
• Conventionally, types & proportions of cotton fibres to be mixed were decided based on cost & previous experience.
• This method cannot assure minimum possible cost without affecting the yarn properties.
• Therefore, any improvement in evaluation, purchase & formulation of cotton mixing is highly valuable.

Importance of cotton quality

For a spinner important cotton fibre properties are 

• length, 
• length uniformity, 
• short fibre content 
• Micronaire (linear density or maturity)
•  Strength
• Trash (type of trash)
• Fibre entanglement known as neps 
• Stickiness
• Colour and grade
• Contaminations

Consequences of poor fibre quality

NON WOVEN fabrics history

Instrumental Evaluation of Cotton

The development of testing instruments like High Volume Instrument (HVI) and Advanced Fibre Information System (AFIS) have revolutionized the concept of cotton testing.

High Volume Instrument (HVI)

It can determine most of the quality parameters within 2 minutes

HVI and Bale Management Software

Advantages

•  Users can minimize risk of purchasing unsuitable cotton
• Minimizing risk of mixing cottons that are statistically not the same

For a mill to fully control the variations in the bale inventory, HVI test data for each bale is necessary.

Testing speed of HVI is upto 150 bales/hour

Spinning Consistency Index (SCI)

➢SCI is a calculation for predicting overall quality & spinnability of cotton fibre

➢Regression equation uses most important HVI parameters: length, length uniformity, micronaire, strength & color

➢Practically, SCI could be first & micronaire could be second parameters for selection of cotton.

➢Single Index : reduces number of actual categories of cotton available for selection

Advantages of SCI in fibre selection

• SCI and yarn strength & quality parameters correlate well
• Reduces & simplifies the number of warehouse categories
• Maintains day-to-day consistency of fibre properties
• Controls within lay down and between lay down variations
• SCI based bale management ensures mixing consistency, thereby yarn strength & spinning end breaks 12

DESIZING || HYDROLYTIC DESIZING

Cotton Fibre Engineering

➢It attempts to optimize cotton fibre use with cost & quality of end product

It consists of four interactive elements:

Four Interactive Elements

1. Cotton purchasing strategy

• Should be bases on technological value of cotton
• Cotton should meet technological requirement
• Cotton may have premium value but it may not be suitable for particular process or end product
• for a given spinning system, factors like count, twist & end product specification influence the kind of cotton

Examples

- Cotton requirement for ring spinning & rotor spinning, - cotton required for finer counts & courser counts

2. Cotton Testing

To know precise variability of cotton bale population, cotton bales are tested at this step

3. Bale Management

• It is strategy for storage & retrieval of bales
• After testing bales can be stored in groups & categories or can be given bale identification number

Why Bale Management?

• Consistent production & yarn quality through homogeneous mixing of cotton
•  Inventory control & selection of fibres according to properties

4. Cotton Fibre Selection

Cotton fibre selection for cotton fibre engineering involves two main procedures

1. Suitable bale picking scheme implementation

- it gives uniform fibre characteristics on mix-to-mix basis without violating inventory constraints

2. Fibre/yarn modeling

- it helps in controlling desired output parameters