The machinery manufacturers have developed many energy conserving ancillaries to reduce energy consumption. Ring spinning is a major consumer of energy and it accounts for 50% of total spinning mill consumption. Studies conducted by SITRA in modern ring frames revealed that about 1/3 of total machine power is spent in driving the spindles. The design and construction parameters of spindle tapes are one of the factors affecting the power consumption of spindles. With this background, we conducted study of new spindle tapes made by thermoplastic polyurethane material.


These W-8 tapes are made of Thermoplastic Polyurethane material and reduce the bending resistance of new spindle tapes significantly, the efficiency of transmission improves due to higher co-efficient of friction at the pulley side and it is reflected in the speed of spindles. The another important aspect of W-8 spindle tapes is the flex proof because the joining area is like the English letter W which does not offer any resistance to the movement of spindle. The experiments were carried out on a modern high speed LR6 ring frame. The spindle speed was measured for both spindle tapes during the study to see their transmission efficiency. The below table shows the increase in spindle speed in this study.

Increase in Spindle Speed with W-8 Tapes

Spindle Speed with HS-5 Tapes (RPM)

Spindle Speed With W-8 Tapes (RPM)

Change in Spindle Speed (RPM)

Increase in Spindle Speed (%)

18107

18530

423

2.33%


It can be seen from the above table that new W-8 spindle tapes always gives higher spindle speed. The increase in spindle speed is due to higher dynamic frictional co-efficient of new tapes. The transmission efficiency of new spindle tape is higher by about 2.33% in our study (423 rpm) as compared with existing HS-5 tapes. This higher speed is due to low slippage of W-8 Spindle tapes.


In this study, care must be taken for TPI correction because change of tapes increases the spindle speed by 423 rpm without any change in delivery speed of front roller. Hence there is increase in TPI in the yarn which we do not require at all in the yarn and higher TPI than recommended is enemy of productivity. In our study, change in TPI is 2.36% on higher side. This increase in twist per inch is altered by suitable twist combination wheels to get nominal twist per inch in the yarn and you see change of TPI as given in table blow.


 

Change in Twist with W-8 Tapes

TPI with HS-5 Tapes

TPI with W-8 Tapes

Change in TPI

Increase in TPI (%)

19.46

19.92

0.46

2.36%


Therefore, the mill can achieve higher production rate due to increase in spindle speed by about 2.33% (423 rpm) with alteration of twist combination wheels.


W-8 Tapes Shorten the doff duration time

Types of Tapes

HS-5

W-8

Remarks

Spindle Speed (RPM)

18107

18530

Increase of 423rpm

Count (Nm)

56

56

-

Twist / Inch

19

19

-

Cop Weight (gm)

60

60

-

Doff Duration (Min)

138.8

135.6

Saving of 3.2min / doff


The above table shows saving of 3.2 min in every doff duration. The doff duration is shortened by 3.2min (2.31%).


Comparison of Cost & Life of HS 5 and W-8 Spindle Tapes

Cost Components

HS-5

W-8

Difference

Price/1m/1cm

8.5

*43

*34.5

Tape Size (Length x Width)

2356mmx11mm

2356mmx11mm

2356mmx11mm

Price/Tape

*22.02

*111.44

*89.42

Cost/m/c of 480 spindles

*2642.4

*13372.8

*10730.4

Life of Tapes

1 years

2 years

year

Monthly Tape Breakage Rate

10 Nos

1Nos

9 Nos

Monthly Tape Replacement Cost

*220.2

*111.44

*108.76


The cost of W-8 tapes is 5 times the cost of HS-5 tapes, but it is worth to use W-8 tapes as these give recurring saving in power and about year more life. The payback is only within 7 to 8 months .The pay back is explained later on at the end of this project.


Comparison of Power Consumption between HS-5 & W-8 Spindle Tapes


The study is being conducted on LR6 ring frames with HS - 5 and W-8 Spindle Tapes and it shows saving of 0.37Kwh power which is about 2%. The following table shows details of saving.

 

 

Consumption with HS-5 Tapes

Consumption with W-8 Tapes

Power Saving with W-8 Tapes

19.05Kwh

18.68Kwh

0.37Kwh


The final closing of any investment made is to know its pay back period to understand whether investment is adding value to process or not. It gives idea about how and in how much time, the investment made will be recovered. This will be helpful in deciding whether the project is implementable or not. The following table shows details of pay back calculation.


Pay Back Period Calculation of W-8 Tapes

Cost of W-8 Tapes / Machine of 480 spindles

*13372.8

Less Cost of HS-5 Tapes /Machine of 480 spindles

*2642.4

Less Saving due to low breakage rate in W-8 Tapes

*978.84

Less Saving due to higher life of W-8 Tapes by 6 months

*880.67

Net additional investment /Machine with W-8 Tapes

*8870.89

Power Saving with W-8 Tapes (Kwh)

0.37 Kwh

Power Tariff /Unit

*4.5 / unit

Monthly Power Saving in Rupees (0.37 x4.5x24x30)

*1198.8

Pay Back Period Months (Investment /Monthly Recovery)

7.4 Months


The pay back period is only within 7 to 8 months and it is short term within year recoverable project. The investment is also not so big. Hence this project is successful and one can implement it. The cost of tapes is recovered in 7 months only and after that there will be recurring saving on account of reduction in power.

The author is a Senior Manager & HOD Spinning PV, Raymond Ltd, Chhindwara (M.P).