Balancing of machines for complete process house :Part-4 Mercerization

For this purpose one Mercerizing machine (chain type) is required.

Machine working speed: 40 m/min, M/c utilization= 75%

Total production per shift (8 hours or 480 min)= (speed x utilization x 480)/100

= (40 x 75 x 480)/100 = 14,400 meter

Total fabric to be mercerized= 50,000/-

14,400 meter fabric treated in 8 hours

50,000 meter…………= (8 x 50,000)/14,400 = Approx 28 hrs

Mercerization:

Treatment of cotton yarn or fabric with concentrated sodium hydroxide for a minute or less is called mercerization. The process of mercerization is named after the John Mercer, who was the first to discover in 1844, that the treatment of cotton with concentrated sodium hydroxide solution brought about permanent changes in the fibre's properties. He claimed that the treatment resulted in significant  increase in the tensile strength, water absorbency and dyeability of the fibres. It was also observed by him that treated material underwent considerable shrinkage. In the case of yarn, contracting in length was observed while in the case of fabric, shrinkage in both the warp and weft direction were observed.The excessive shrinkage in the cotton yarn and fabric make this process nonviable in the industry thus it was not commercialised. 

It took more than forty years until it was found by H.A.Lowe that shrinkage could be prevented if the yarns or fabrics were kept under tension during mercerization. When mercerizing is done under tension, the fibre also acquire a silk-like luster.