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SITRA News
This issue of SITRA NEWS
covers the fol low ing topics:
Page no.
PRODUCTIVITY AND COSTS
30thCosts, operational performance and yarn
quality: Inter-mill study of key factors
(April - June 2014) 1
TECHNICAL NOTES
1. Impurities in a finishing chemical- A case study 5
2. Factors to be considered while selecting needle lubricant
for modern knitting machines 8
3. Cotton stickiness - Issues and solutions
- Part 1 10
CONSULTANCY SERVICES OFFERED BY SITRA
DURING SEPTEMBER OCTOBER 2014 13
STAFF NEWS 14
CONFERENCES AND SEMINARS 16
TRAINING PROGRAMMES 17
ABSTRACTS OF TECHNICAL ARTICLES 19
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30thCosts, operational performance and yarn
quality: Inter-mill study of key factors
(April - June 2014)
This study is thirtieth in the series on inter-mill study on Costs,
Operational Performance and Yarn Quality. In this study, 142 mills
had participated. The following are some of the main findings of the
study.
Comparison with last study (April-June 2013)
A comparison has been made with respect to 8 costs and operational
parameters against the last study. Based on the deviations in the
average values, relative changes in the individual mills performance
have been identified with respect to 86 mills which had participated in
both the studies.
In the 2nd quarter of 2014, mills on the whole faced a setback in the
performance by recording a significant fall of Rs 840 per spindle per
year in the contribution (by 14%) as compared to the correspondingquarter of 2013 (Table 1), which was mainly due to the substantial
increase in the raw material cost (by Rs 2940 per spindle per year).
The sale value, however, registered a huge increase of Rs 2280 per
spindle per year which was mainly due to the increase in the yarn
selling price (by 60%) and partly because of the jump in the machine
productivity (40%). The production per spindle and spindle utilisation
respectively registered a marginal increase of 2% and one percentage
point. While the power cost recorded a marginal drop (by Rs 110 per
spindle per year), the salaries and wages cost registered a significantincrease of Rs 290 per spindle per year.
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The huge increase in the yarn sale value and a marginal reduction inthe power cost, however, could not off-set the increase registered by
the raw material cost and salaries and wages cost, due to which the
mills had experienced a significant drop in the contribution.
It is interesting to note that almost none of these common mills had
registered a negative contribution in both the studies. Though, on the
whole, these mills had experienced a drop in the contribution in the
30th study, nevertheless, the average contribution earned by them in
the 2nd
quarter of 2014 was fairly high at Rs 5260 per spindle per year.
Further analysis shows that out of the 86 common mills, only one-
third (28 mills) registered an increase in the contribution (by Rs 990
per spindle per year), the increase ranging from Rs 90 to Rs 4470
between mills (Figure 1). The remaining mills recorded a drop of Rs
1760 per spindle per year in the contribution, the drop ranging from Rs
40 to Rs 4930 between mills which was due to the increase in the two
major input costs viz., raw material cost and salaries and wages cost
which more than off-set the increase in the yarn sale value. On theother hand, the increase in the contribution in the 28 mills was largely
due to the increase in the sale value (by Rs 4030 per spindle per year)
and reduction in the power cost (by Rs 150 per spindle per year) which
more than off-set the increase in the two other major input costs (by
Rs 3190 per spindle per year).
Figure 1 Differences in the contribution between the two studies
(Q2 of 2013 and Q2 of 2014)
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Table 1 Comparison of costs and operational parameters betweenthe two studies
Coun t-wise raw m ater ial cost, yarn sel l ing price and NOV
The YSP, RMC and NOV of 18 common counts for which 5 and above
mills had furnished the data in both 29th and 30th studies are given in
Table 2. It can be seen that except in two counts (20s OE and 60s C-
Comp.- Ex.), the mills had faced a setback in the performance during
Q2 of 2014, as compared to Q2 of 2013, by recording about 15% drop
in the NOV. The raw material cost in these 16 counts had registered a
whopping increase of 19% which overshadowed the increase registered
by the YSP (by 3.8%), thereby resulting in the above drop in the NOV.
Even during the adverse trading condition in the Q2 of 2014, in the
combed compact yarns, the drop in the NOV was at lower level (by
about 10%) when compared to that recorded by the remaining varieties
of yarns viz. carded, combed and combed hosiery - both domestic
and export. In fact, the combed hosiery export yarns registered a huge
drop of about 20% in the NOV.
Parameter
Common mills (86) average
29th study
(Apr.- June 2013)
30th study
(Apr.- June 2014)
Contribution - Rs/spindle/year 6100 5260
Salaries and wages cost - Rs/spindle/year 1870 2160
Power cost - Rs/spindle/year 3370 3260
Raw material cost - Rs/kg of yarn
- Rs/spindle/year
135
15150
158
18090
Yarn selling price - Rs/kg 256 268
Yarn sale value - Rs/spindle/year 26490 28770
Prodn./spl./8 hrs.(adj.to 40s) in g 101 103
Spindle utilisation (%) 93 94
Average count 46s 47s
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Table 2Count-wise yarn selling price, raw material costand NOV in the two studies (Q2 of 2013 and 2014)
.
*INCREASE
Raw material cost relat ive to yarn sel l ing pric e
All the 17 ring spun yarns registered an increase in the cotton cost
relative to yarn selling price (by 6 to 12 percentage points) (Table 3).
Count
Yarn selling price(Rs/kg)
Raw material cost(Rs/kg of yarn)
NOV(Rs/kg of yarn)
April -June
2013
April-June
2014
%
inc.
April-June
2013
April-June
2014
%
inc.
Apri -June
2013
April -June
2014
%
reduction
20s OE 135.5 143.6 6.0 94.5 96.3 1.9 41.0 47.3 15.4*
40s K 207.1 212.7 2.7 122.9 142.4 15.9 84.2 70.3 16.5
40s C 234.0 239.0 2.1 138.9 162.0 16.6 95.1 77.0 19.0
60s C 287.4 290.0 0.9 143.5 165.5 15.3 143.9 124.5 13.580s C 351.5 363.0 3.3 154.6 189.9 22.8 196.9 173.1 12.1100s C 441.5 457.8 3.7 174.4 231.6 32.8 267.1 226.2 15.3
40s C-Comp. 245.7 250.5 2.0 141.5 158.2 11.8 104.2 92.3 11.4
50s C-Comp. 295.8 304.1 2.8 146.1 173.0 18.4 149.7 131.1 12.460s C-Comp. 321.0 339.1 5.6 150.0 185.7 23.8 171.0 153.4 10.3
80s C-Comp. 402.3 445.8 10.8 169.2 223.9 32.3 233.1 221.9 4.8
30s CH 205.8 216.4 5.2 136.8 157.7 15.3 69.0 58.7 14.9
34s CH 215.6 226.0 4.8 136.3 156.6 14.9 79.3 69.4 12.540s CH 228.2 232.6 1.9 139.2 163.3 17.3 89.0 69.3 22.1
60s C-Comp.-Ex. 309.7 390.8 26.2 152.3 215.8 41.7 157.4 175.0 11.2*
26s CH-Ex. 221.9 224.8 1.3 143.9 172.4 19.8 78.0 52.4 32.830s CH-Ex. 207.1 221.5 7.0 133.1 162.7 22.2 74.0 58.8 20.540s CH-Ex. 236.2 245.7 4.0 140.9 166.1 17.9 95.3 79.6 16.5
50s CH-Ex. 256.4 262.5 2.4 143.1 162.9 13.8 113.3 99.6 12.1
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Table 3Count-wise raw material cost relative to yarn selling price inthe two studies
* drop
- D.Shanmuganandam & J.SreenivasanLiaison and Consultation Division
1. Impurities in a finishing chemical A case study
A finisher buys a certain chemical on the understanding that it should
not contain more than 3% impurities. When a batch was delivered, five
independent determinations of percentage impurity in the chemical
were made and the results are given in Table 1.
Count
April-
June
2013
(A)
April-
June
2014
(B)
Increase
(percentagepoints)
(A-B)
Count
April-
June
2013
(A)
April-
June
2014
(B)
Increase
(percentagepoints)
(A-B)
20s OE 69.7 67.1 2.6* 40s CH-Ex. 59.7 67.6 7.9
40s C-Comp. 57.6 63.2 5.6 60s C-Comp. 46.7 54.8 8.1
60s C-Comp.-Ex. 49.2 55.2 6.0 80s C-Comp. 42.1 50.2 8.1
34s CH 63.2 69.3 6.1 80s C 44.0 52.3 8.3
50s CH-Ex. 55.8 62.1 6.3 40s C 59.4 67.8 8.4
30s CH 66.5 72.9 6.4 40s CH 61.0 70.2 9.2
60s C 49.9 57.1 7.2 30s CH-Ex. 64.3 73.5 9.2
50s C-Comp. 49.4 56.9 7.5 100s C 39.5 50.6 11.1
40s K 59.3 66.9 7.6 26s CH-Ex. 64.8 76.7 11.9
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Table 1 Impurity level in finishing chemical
Is there sufficient evidence to conclude that the batch contains too
much impurity?
In the present problem,
3.2 + 3.4 + 2.8 + 3.1 + 3.1
Mean value of the 5 impurity determinations =
5
= 3.12Standard Deviation of the 5 impurity values (SD) = 0.217
Standard Error of the impurity values (SE) =
where n is the number of determinations of percentage impurity
Standard Error of the 5 impurity values (SE) = = 0.097
Actual Mean Impurity - Expected Mean Impurity
t value =
Standard Error of Impurity Values
3.12 - 3
=
0.097
= 1.24
Test no. Impurity (%)
1 3.2
2 3.4
3 2.8
4 3.1
5 3.1
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A condensed version of the t table for different degrees of freedom isgiven in Table 2.
Table 2 t values for the different degrees of freedom
(95% significant level)
t value from the statistical table for 4 degrees of freedom (df = No. of
observations - 1 ie. 5 1 = 4) at 95% level of significance is 2.78.
Since the calculated value of t (1.24) is lower than the value given in
the statistical table (2.78), the difference between the two values under
question is not statistically significant.
Hence, it may be deduced that there is no evidence to conclude that
the level of impurities in the delivered batch is higher than the expected
level of 3%.
- Dr. K.P.Chellamani
Spinning Division
Degrees offreedom
t valueDegrees of
freedomt value
1 12.71 13 2.16
2 4.30 14 2.143 3.18 15 2.13
4 2.78 16 2.12
5 2.57 17 2.11
6 2.45 18 2.10
7 2.36 19 2.09
8 2.31 20 2.09
9 2.26 21 2.08
10 2.22 22 2.0711 2.20 23 2.07
12 2.18 24 2.06
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2. Factors to be considered while selecting a needle
lubricant for modern knitting machines
The basic function of a needle lubricant is to ensure that the needles
and knitting elements of the machine run smoothly with minimum wear
even under high temperature and pressure so that the optimum life of
the machine is realized. Some of the parameters that need to be
considered while selecting a lubricant oil for modern knitting machines
are discussed below.
a) Oil viscosity
Optimum viscosity of oil ensures that the oil has the appropriate
thickness at normal machine operating temperature. Too low oil
viscosity leads to quicker drain out of the oil from the machine surfaces
and does not warrant the presence of oil film on the machine parts
requiring lubrication. This could lead to premature wear of the knitting
elements. If the oil is too viscous, cold starting of the machine will be
difficult and the oil may not flow sufficiently between the moving parts
as clearances are reduced when the machine heats up and expands.
Too viscous oil can result in the machine running at a higher than
expected temperature, again possibly compromising the wear rate.
Mostly, the required viscosity levels are recommended by the knitting
machine manufacturers. ISO 22 viscosity grade oils are the most widely
recommended oils for modern machines though ISO 15 and 32 grade
oils are suggested in a few cases.
b) Oil additives
The choice of additives incorporated in oils is critical. Additives may
be used to modify the frictional properties of oil but primarily are used
to give improvements in the anti-wear performance, oxidation resistance
and corrosion resistance. Modern knitting machines are engineered
with close machine tolerances, have steep cam angles and high
peripheral speeds and potentially operate 24 hours a day, all demanding
a very high performance in terms of the anti-wear properties of the oil.
Anti-oxidants reduce the rate of oil deterioration and prevent the rapid
formation of sticky or resinous deposits. Corrosion resistance is
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important for the protection of the machine.
c) Compatibility with machine components
The oil selected should have good compatibility with the materials
used in the manufacture of modern machines viz., plastic components,
electric cabling, rubber seals, electronic actuators and not the least,
machine paints.
d) Scourability
The needle oil in consideration should not only lubricate and protect
the machine but also have a part to play in ensuring the production of
good quality fabric. Hence, the oil should be selected keeping in mind
the type of fibres / yarn being knitted and the processing / finishing
route of the fabric when it leaves the knitting machine. In case of
splashing onto the fabric, the oil stain thus formed on the fabric should
be easily scourable. The lubricant oil should display superior
scourability from cotton, cotton / synthetic or 100% synthetic fabricsand effective scouring performance from fabrics knitted from dyed yarns,
mlange yarns and protein fibres such as wool / silk.
e) Suitability for elastane yarns
Special type of oils are to be used in the knitting of fabrics containing
elastane yarns, where the fabric is heat-set prior to the scouring
process. Ordinary oils disintegrate and stain the fabric at high
temperatures applied during heat-setting. Hence, the need for suchspeciality oils.
f) Presence of heavy metals
Lubricant oils should be free from heavy metals such as Lead, Nickel,
Manganese, Arsenic, Copper, Chromium, etc in order to be environment
friendly. Also, this is one of the requirements of organic certification
and a few other Eco labels that the lubricant oils used in manufacturing
site should be free from heavy metals or if present, the metals shall bewithin the allowable limits that are prescribed in the respective
standards.
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The typical characteristics of a needle lubricant shall be as given below:
ISO viscosity grade : 22
Viscosity @ 400C : Approx. 22 cSt
Viscosity Index : 95 to 96
Density @ 150C : Approx. 0.86 to 0.89 kg /l
Cloud point : Below 00C
Flash Point : Above 1300C (SETA)
Ionic nature : Non-ionic / Anionic
The oils suitable for Elastane yarns can be of Non-ionic / Cationic in nature
pH Value : Approx. 4.5 as 10% emulsion
Emulsifiability : Self emulsifiable in water
Colour : Pale to Dark yellow
- S. Sivakumar
Textile Chemistry Division
Stickiness of cotton is an universal problem. Cotton being an important
fibre crop for many developing countries like India, several attempts
were made all over the world to overcome this problem. With the advent
of fourth generation high speed processing machines, the problem of
stickiness has assumed greater significance. SITRA has conducted alarge number of studies towards processing cottons with a relatively
higher level of sticking tendency.
Understanding the importance of this parameter in the processing of
cottons, we are commencing from this issue a new series to focus on
these aspects.
The sticking tendency of cotton is mainly due to the non-cellulosic
matter present in cotton. The chemical constituents of a typical cottonfibre are given below in Table 1.
3. Cotton Stickiness - Issues and solutions
- Part 1
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Table 1 Chemical constituents of cotton fibre*
Sticky cottons are troublesome at the ginning stage itself by way of
reduced throughput. In the spinning process, deposits form on the
card crush rolls, drawing and comber rolls, and also on the top and
bottom drafting rollers of speed frames and ring frames. These deposits,
in due course of time, build up sufficiently to cause roller lapping andcause disruption of the production process.
At the carding stage, the most acute problem while processing sticky
cottons is the lapping on the card crush rolls and sometimes loading
of fibres on card cylinder. Generally, as thickness of fibre batt passing
between rollers decreases, the sticking tendency of cotton increases.
Yarns produced from sticky cottons are in general, weak, uneven,
neppy and are rated poor in appearance than yarns produced from
non-sticky cottons. Results of experiments conducted at SITRA confirmthe poor spinning performance of sticky cottons in terms of higher
ends down in spinning, higher values of yarn unevenness &
imperfections, etc.
The apparent effect of the sticky nature of cotton is reflected as the
number of roller lappings at various stages of spinning. In other words,
cotton stickiness and roller lapping are respectively the cause and
effect of a particular problem. The causes for roller lapping can be
broadly classified as (i) fibre factors and (ii) machinery factors.
* Henry H.Perkins., Some observations on sticky cottons, Textile
industries, Vol. 3, 1991, pp. 365-373.
Constituent % Dry weight
Cellulose 94.0
Proteins 1.3
Pectic Substances 0.9
Ash 1.2
Wax 0.6
Organic Acids 0.8Sugars 0.3
Others 0.9
Total 100.0
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The inherent cotton fibre characteristics like maturity, micronaire value,wax content and other non cellulosic constituents play a greater role
in making the cotton fibres sticky in nature. In addition, certain
contaminants like crushed seeds, immature seeds, oily substances,
etc., also influence the sticking tendency of cotton during processing.
Fibre Fineness
Fibre fineness is an intrinsic property of the type of cotton and it varies
from as low as 2.8 to as high as 6.2 micronaire. As the fibre micronairevalue decreases (fineness increases), the bending rigidity decreases
proportional to the square of micronaire and consequently, the fibre
exhibits greater tendency to follow the curvature of the rollers. Therefore,
loose fibres not held by the twist inserted in the yarn are most likely to
lap over the top or bottom drafting rollers and try to gather enough
fibres from the yarn to cause an end break and subsequently lapping.
It follows from this that finer fibres are more prone to lapping. Moreover,
the lapping tendency increases as the number of fibres coming in
contact with either the top or bottom rollers (area of contact) increases.This also implies that finer fibres will have higher lapping tendency and
vice versa. Cotton fibres with micronaire value lower than 3.0 are
generally found to be lap-prone.
Fibre Maturity
Maturity is a factor indicating the degree of development of a cotton
fibre. Like fibre fineness, the maturity also varies among different types
of cottons and also within a cotton type depending upon the growingand harvesting conditions. Low maturity cottons generally record lower
micronaire values and vice versa. Hence, the mechanism of lapping for
finer fibres also holds good for cotton with low maturity values. Cotton
fibres with number of mature fibres less than 60%, normally exhibit
higher level of roller lapping.
Immature cotton fibres, in addition to low bending rigidity, have higher
concentration of monosaccharides (mainly fructose and glucose), which
are directly related to the sticking nature of cotton. Presence of large
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MEDICAL TEXTILES - 11 S.no. Type of study No. of mills
Consultancy services offered by SITRA
during September - October 2014
1. Machinery valuation 1
2. Techno-economic viability study 1
3. A study on MIS 1
4. Performance improvement study 1
5. Productivity and maintenance audit 1
6. Steam energy audit 1
7. Power consumption analysis for air compressor 18. ACS for humidification plants & compressors 1
9. Energy audit 1
10. A study on the water consumption of soft flow
dyeing machines while processing bleaching
and washing lots 1
11. A solution to prevent dusting-off on burn-out
printed garments 1
12. Process route to eliminate oil line marks on
fleece knitted fabrics 1 13. Elimination of crease marks while processing
grey mlange fabrics 1
14. Process route to minimize roll to roll shade
variation in knitted fabrics dyed using reactive
dyes 1
Besides the above consultancy studies, SITRA also offered solutions
to two adhoc problems in the area of spinning. Sixty nine instruments
were calibrated and 255 accessory samples were tested.
absolute amounts of B D fructose, X D glucose and B D glucosemakes the cotton fibre lap-prone.
To be continued
- K.P.Chellamani & M.K.Vittopa, Spinning Division
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Meetings attended
Dr. Prakash Vasudevan, Director, attended the following meetings at
Ministry of Textiles, New Delhi on 8th
September, 2014:
- Eighth meeting of Empowered Committee constituted under
Technology Mission on Technical Textiles (TMTT).
- Review of progress in transition to new MIS launched in ISDS.
Dr. K.P.Chellamani, General Manager - Projects, attended the following
meetings:
- Purchase Committee meeting of the COEIndutech at P.S.G.
College of Technology, Coimbatore on istand 19thSeptember, 2014.
- Conducted the viva-voce examination of Mrs.Vijayalakshmi, Ph.D.
scholar of Anna University, Chennai at P.S.G. College of
Technology, Coimbatore on 29thSeptember, 2014.
- Conducted the viva-voce examination of Mr.C.Prakash, Ph.D.
scholar of Anna University, Chennai at Kumaraguru College of
Technology, Coimbatore on 9thOctober, 2014.
Seminars / Conferences attended
Dr. Prakash Vasu devan, Director, attended National Handloom
Development Corporation (NHDC) buyer seller meet at Jenneys
Residency, Coimbatore on 5thSeptember, 2014.
Mr. Sakthiv el Perum alsamy, Head - Centre of Excellence for Medical
Textiles, attended a workshop conducted by Department of HealthResearch (DHR) / Indian Council of Medical Research (ICMR) on Medical
Diagnostics and Devices Innovation held at New Delhi on 19th& 20th
September, 2014.
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Paper published
Dr.K .P.Chel laman i, M.K .Vi t to pa an d S.Sivakumar, Studies on
quality attributes of Bt-cottons Asian Textile Journal, October 2014,
Volume 23, Issue 10, pp. 68-72.
Papers presented / Lectures given
Dr.K.P.Chellamanidelivered the following lectures at Gandhigram
Deemed University, Dindigul:
- Total Quality Management in an R & D Set-up at the programme
entitled Managerial Strategies on 2ndSeptember 2014.
- Process-Re-engineering at the Enterpreneurs Development
Programme on 7thOctober 2014.
- Small Group Activities in a Decentralized Sector at the conference
held on 14thOctober 2014
Mr.S.Sivakumar, Head Incharge (Textile Chemistry) delivered a
guest lecture on Defects in knitted fabrics and their remedies at the
16thAnnual General body Meeting of the South India Imported Machine
Knitters Association (SIIMKA) on 13th September, 2014.
Overseas visit
Dr. Prakash Vasudevan, Director, visited the following Institutes inTaiwan and Hongkong during his one week overseas visit:
- Taiwan Textile Research Institute (TTRI), Taiwan .
- The Hongkong Research Institute of Textiles and Apparel (HK
RITA).
- SDL ATLAS, Hongkong.
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Research Projects Review
Dr.K.P.Chellamani, has reviewed the Terminal Report of the Research
Project Development of low cost jute bags for food grains and sugar
submitted by Indian Jute Industries Research Association (IJIRA),
Kolkata.
Seminar on Energy conservation in industry
With an aim to create an awareness among industry personnel the
importance of conservating energy, SITRA organised a seminar on
Energy conservation in Industry on 27thOctober, 2014 at SITRA.Around 300 participants representing various textile mills and other
industries, apart from faculty and students from different colleges
attended the seminar. A SITRA publication entitled Fundamentals of
Electricity Management in Industry was released on the occassion.
Six different technical papers of relevance and current interest in the
field of energy conservation were presented in the seminar.
Mr.N.Vasanthakumar, Junior Scientific Officer, Textile Engineering &
Instrumentation Division presented a paper on Selection of energyefficient electrical utilities.
International workshop on Biocompatibility evaluation of
medical devices
An International workshop on biocompatibility evaluation of medical
devices Sponsored by the Ministry of Textiles, Govt. of India was
organised by the Centre of Excellence for Medical Textiles, SITRA at
SITRA, from 15th
- 18th
October, 2014. Expert speakers from the De-partment of Microbiology and Mutagenicity, Bioneeds, Bangalore
and the Skin Ethic Laboratory, France delivered lectures relating to
CONFERENCES AND SEMINARS
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biocompatable evaluation of medical devices with a focus on ISO 10993.Totally, 25 persons took part in the workshop.
Seminar on Coating and laminating technologies
Module - I
Centre of Excellence for Medical Textiles, SITRA organized a 5-day
seminar on Coating and laminating technologies Module - I from 23rd
to 27th September, 2014 at SITRA. Specialist speakers from Pune
conducted the sessions. Topics like, polymers used for the manufactureof adhesive, adhesive types, additives for PSA, combination of various
resins, anti oxidants for adhesive, poly isobutene as tackifier and fire
retardant additives were discussed in the seminar. Totally, 26 persons
took part in the seminar.
Training Programme on Low Voltage Switchgear Selection &
Maintenance
With the objective of enhancing the knowledge of electrical personnelworking in various industries on key aspects involved in the selection,
operation and maintenance of low voltage switchgears, SITRA, in
collaboration with L&T (the pioneers in switchgears) planned 5 one-
day training programmes as independent modules - i) Circuit breakers,
ii) Contactors & OLR, HRC fuses, iii) Motor starters & MPCBs, iv)
MCBs, ELCBs & DBs and v) Fault level calculations, Numerical relays,
BBT and MV switchgear. The first two modules were held during June
and July, 2014 wherein 14 persons participated. The last three modules
were held during September and October 2014 wherein a total of 36persons participated.
TRAINING
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Technical Entrepreneur Development programme on
Shuttleless weaving
The programme was organised with the objective of educating young
entrepreneurs on the technologies involved in weaving, case studies
relating to woven fabric defects and remedial measures, TUF scheme,
various sources of availing loans, the modalities involved in setting up
new units etc. Nine persons comprising Managing Directors, senior
executives and technical personnel attended the programme.
Training programme on Shuttleless weaving machines
An Engineering College in Tamil Nadu availed SITRAs services to
conduct a training programme for its students on Shuttleless weaving
machines. The programme covered topics like basics of weaving
machines, modern developments, shuttleless weaving principles and
practical training on shuttleless looms. Totally, 60 students and 8 staff
were trained in 3 batches from 27.9.2014 to 30.9.2014.
Awareness programme on Eco-parameters
SITRA conducted an awareness programme on Eco-parameters at
Workshed, PLSC - Salem for supervisory and middle managerial staff
working in processing mills, job work units and garment exporters.
The programme was conducted in September, 2014 and covered topics
like sources for banned chemicals in textile supply chain, testing of
eco-parameters and certification procedures, methods to removehazardous substances from finished textile products apart from dealing
with case studies. Totally, 20 persons took part in the programme.
Pre-employment training and retraining programmes for textile
workers
Two out-station mills and one local mill availed SITRAs training services
for their workers. Two hundred and seventy operatives in preparatory,
spinning, auto cone winding and doubling departments were trained in15 batches. The training programmes were conducted in Tamil and
Kannada.
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AN INNOVATIVE TWISTING MECHANISM BASED ON
SUPERCONDUCTING TECHNOLOGY IN A RING-SPINNING
SYSTEMMahmud Hossain et al, Textile Research Journal, May 2014,
Volume 84, Issue 8, pp. 871 - 880.
Twist plays an important role to impart tensile strength in yarn during
the spinning process. In the most widely used ring-spinning machine
for short staple yarn production, a combination of ring and traveler is
used for inserting twist and winding the yarn on cops. The main limitation
of this twisting mechanism is the friction between the ring and traveler,
which generates heat at higher speeds and limits the productivity.This limitation can be overcome by the implementation of a magnetic
bearing system based on superconducting technology, which replaces
completely the existing ring/traveler system of the ring-spinning
machine. This superconducting magnet bearing consists of a circular
superconductor and permanent magnet ring. After cooling the
superconductor below its transition temperature, the permanent magnet
ring levitates and is free to rotate above the superconductor ring
according to the principles of superconducting levitation and pinning.
Thus the superconducting magnetic bearing (SMB) ensures a friction-free operation during spinning and allows one to increase spindle
speeds and productivity drastically.
The SMB is comprised of a superconducting material and a magnetic
component. In general, the two well known designs of SMB can be
applied as twisting and winding devices in the conventional ring
spinning machine:
1. SMB1, where a magnetic ring rotates coaxially over a
superconductor ring;
2. SMB2, where a magnetic ring rotates coplanarly inside the
superconductor ring.
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SMB 1 is composed of a neodymium-iron-boron (NdFeB) magnet ringprovided by IBS Magnet and a superconductor ring yarn YBCO (Yttrium
barium Copper Oxide) provided by evico GmbH. NdFeB is one of the
strongest PMs (Permanent Magnet) with very good magnetic
properties. The density of NdFeB is 7.4 g/cm3and the fracture strength
is 80 MPa. For a magnet with a diameter of 10cm, a maximum rotation
speed of Ca. 28,400 rpm is possible, taking into account the tensile
stress and fracture strength. In order to realize higher rotation speeds,
the PM ring has to be reinforced. YBCO (YBa2Cu
3O
7-x), on the other
hand, is a crystalline chemical compound and a popular high-temperature superconductor, achieving superconductivity at transition
temperature, Tc= 1840C above the boiling point of liquid nitrogen (-
196.150C). For the technical application, the pining force must be as
strong as possible. Strong pinning forces can be realized in melt-
textured bulk YBCO material. It is possible to manufacture
superconducting YBCO magnets that can produce magnetic fields of
16 Tesla at 2490C and attractive or repulsive levitation forces up to
5000 N/cm2.
The authors report that they have spun 31 Tex 100% polyester yarn
using SMB as well as conventional ring spinning with the ring/traveler
system.
The SMB yarn was found to be more even with fewer projecting hairs.
According to the authors, the SMB can revolutionize the twisting
principle of yarn formation and can help to increase the spindle speed
substantially.
- R.S.Vignesh BalajiSpinning Division
YARN PERFORMANCE WITH COLD SIZING
Hrishikesh V. Chavan, Suraj S. Patil, D.K.T.E.S. Textile & Engineering
Institute, Ichalkaranji / India
Melliand International, June, 2014, No. 2, pp 84 to 86.
Energy conservation has received a high recognition these days. The
sizing department mainly consumes steam energy for preparation ofsize paste and drying of warp sheet. In this paper, the authors have
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studied and compared the performance of yarn sized through normalhot sizing process vis--vis the cold sizing process. Cold sizing is the
process in which the spun yarn (grey or dyed) in the form of a cone or
cheese is single end sized at room temperature during winding using
a special attachment for sizing and drying before winding onto a cone.
This process eliminates the need for preparation of warp beams and
hot sizing thus saving time, energy and cost. More importantly, it aids
the small scale industries which cannot afford to have warping and
sizing ranges to facilitate their yarn preparation for weaving.
Cold sizing has certain advantages over conventional hot sizing in
terms of savings in energy and time, requires less labour, reduces
dead loss, end breaks and machine downtime in the loom shed, etc.
The authors found that cold size can be preserved for 3-4 days without
deterioration in its properties and with no lump formation, thus giving
excellent results in end breaks at loom shed with less dust formation
and less pollution.
In this study, 40s carded 100% cotton ring spun yarn was used by theauthors to conduct trials by sizing the yarn through various methods
viz., hot sizing with Maize, Tapioca starches and cold sizing. The
authors report that the yarn co-efficient of friction against metal was
reduced by almost 50% in cold sized yarns when compared to that of
normal sized yarn, hence, breakage due to excessive friction between
reed eyes and travelling yarn can be reduced. Cold sized yarns gave
higher breaking force and elongation at break than the normal sized
yarns. The authors had inferred that the cold sized yarns had shown
higher abrasion resistance than the normal sized yarns and hencerendered improved weavability. Cold sized yarns recorded much less
hairiness than the normal sized yarns, hence problems in shed opening
during shed formation are expected to be less. Finally, the authors
concluded that, cold sized yarns gave better performance compared
to the normal sized yarn in terms of properties like strength, elongation,
hairiness and abrasion resistance.
- S. Sivakumar & S. Kowsalya
Textile Chemistry Division