Monday, November 16, 2020



When the cotton bolls pass through the ginning machine, the cotton seeds get separated from cotton fibres. The broken leaves, dust also get removed up to some extent. Some cotton seeds also get broken during the ginning process. The seed coats do not eliminate from cotton.  The ginned cotton has many impurities in it. We can say that any type of impurities present in cotton fibres is called trash. Such impurities are plant leaves, seed coats, and dust etc. 

The amount of trash in the cotton fibres is expressed in terms of percentage. Trash percentage plays a decisive role in the cotton price. The quality of the yarn is also affected by the trash percentage present in cotton fibres. Low trash percentage ensures a better quality of yarn. Low trash percentage cotton has a high price in comparison to cotton having a high trash percentage in the same cotton variety. 

The trash percentage is analysed accurately before purchasing the cotton. 

Trash elimination process:

1 - The cotton lints are placed on the feed table.

2 - The cotton lints are opened manually by hand before placing them on the feed table.

3 - The lints feeding is done uniformly.

4 - A fairly thin fleece of cotton lints feeds in the analyzer.

5 - Half of the lints are placed on the feed table in the form of a uniform fleece before starting the trash analyzer. The remaining lints are added during a test.

6 - The hard lumps of trash and full cotton seeds are picked up manually from the test samples and are weighed with trash.

7 - If these trash lumps and full seeds are allowed to feed with cotton lints, the feed table plate and taker-in wire points may get damaged.

8 - The airflow control valve is opened at beginning of the test and this valve is closed after the end of each test.

Method of trash analysis in cotton fibres: 

The whole method of trash analysis is given below:

1 - 100 gms of cotton is weighed accurately. It is passed through a Shirley trash analyzer.

2 – The cotton lints are passed a minimum of two times through the trash analyzer. 

3 – If the trash is still found to contain a sizable amount of lints, the trash is further processed through a trash analyzer.

4 -  The lints found after two or three times proceedings are weighed together.

5 – The amount of trash is weighed after the final proceeding.

6 – Now the trash percentage and invisible loss are calculated.

7 – Generally, two samples of 100 gms each are analysed separately.

8 – The average of both samples is calculated.

Trash Calculation:

Analysis of Trash :

The collected visible trash is passed through a wire mesh of mesh size of BS - 10 and BS - 36  and is analysed as below:

Trash over mesh 10  - Seed coats 

Trash over mesh 36  - Leafy matter & kitties etc.

Trash below mesh 36 - Dust etc.

The cleaning efficiency of the machine:

The cleaning efficiency helps to evaluate the performance of a machine. If the cleaning efficiency falls below a certain level, the machine settings need to be checked. The removal of trash particles such as seed and leaf particles, stalks, sand, and dust from cotton is quantitatively expressed as cleaning efficiency which can be estimated as below:

About 200 grams of sample is collected from the feed and delivery of a machine like blow room or card. These collected samples are analysed for trash content. This analysis is carried out by processing a 100 grams of a sample through a Shirley trash analyzer. The resulting Trash is collected and weighed accurately. Two samples are analysed and average trash content is calculated.

Speeds and settings of Shirley trash analyzer:

Speeds :


Feed plate to taker - in  = 4/1000 inches

Streamer plate  to taker - in( lead in edge) = 5/1000 inches

Streamer plate  to taker in ( lead-off edge) = 7/ 1000 inches

Stripping knife to taker - in ( bottom edge)  = 4/1000 inches

Stripping knife to a cage ( lead in edge) = 5/16 inches

Taker-in to cage = 13/164 to 15/64 inches

Separation sheet to cage ( top edge) = 1/4 inches

Delivery plate to cage = 1/16 inches

Please click on the below video link to watch the full topic in Hindi:

No comments:

Post a Comment

Featured Post

Simple calipers and vernier calipers, method of uses and calculations

Calipers: The calipers are very useful instruments. These instruments are used to measure the diameter of the cylinder, bore, bearing size, ...