Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

FIBER LENGTH

•
•
Nitish Sharma
Nitish Sharma

This presentation contain about fiber length and various type of length and also the ways to measure span length , effective length,mean length etc.

1 of 20
DEPARTMENT OF TEXTILE PRESENTATION ON FIBRE LENGTH
Why fibre length? • Quality assessment, Fibre breakage study, machine settings, combing efficiency, etc. • Length of staple fibre is one of the most important characteristics. In general a longer average fibre length is to be preferred because it confers a number of advantages. Firstly, longer fibres are easier to process. Secondly, more even yarns can be produced from them because there are less fiber ends in a given length of yarn. Thirdly, a higher strength yarn can be produced from them for the same level of twist. • The length and fineness are sometimes related in natural fibres whereas for man-made fibres, length and fineness can be controlled separately.
DEFINITIONS OF FIBRE LENGTH PARAMETRES:- • Mean length : The arithmetic mean of the length of all the fibres present in a small but representative sample of cotton, based on weight-length distribution or relative number-length distribution. • Upper Quartile Length: The length for which 75 per cent of all the observed values are lower and 25 per cent higher, by weight or by number
• Effective Length : It is difficult to give a clear scientific definition for effective length. It may be defined as the upper quartile of the numerical length distribution from which some of the shortest fibres are eliminated by an arbitrary construction. The fibres eliminated are those shorter than half the effective length. • Span Length : The distance spanned by a specified percentage of the fibres in the test beard. 2.5% span length is the distance from the clamp on a fibre beard to a point upto which only 2.5% of the fibres extend.
MEASUREMENT OF FIBRE LENGTH :- • 1. HAND STAPLING METHOD. • 2. COMB SORTER METHOD. • 3. PHOTO ELECTRIC METHOD (FIBRO GRAPH). • 4. SHIRLEY PHOTO ELECTRICAL METHOD. • 5. WIRA FIBRE LENGTH MACHINE.
HAND STAPLING METHOD : (By trained classers) • Selecting a sample and preparing the fibres by hand doubling and drawing to give a fairly well straightened tuft of about ½ inch wide. • This is laid on flat black background and the staple length is measured. • The shorter fibres will lie in body of the tuft and extreme ends (tips) will not be the limits used for measurement of staple length. • The classer chooses the length where there are reasonably well defined edges • Subjective in nature, so difference in results between classers.
Comb Sorter Method:
In the diagram OQ = 1/2 OA OK = 1/4 OP KS = 1/2 KK’ OL = 1/4 OR Short fibre percentage = (RB/OB) × 100% LL’ = Effective length (because many m/c settings are related with this length) LL’-MM’ = NL’=Inter-quartile range Dispersion% = NL’/LL’ (For flatter middle zone, dispersion is minimum) Frequency distribution in opposite way, i.e. the curve is known but the frequency distribution is to be obtained.
FIBER LENGTH
Comb sorter diagram analysis: Staple length US'' + 3/32'' = EL'' (34/32'' - 39/32'') Staple length US''+ 1/8'' = EL'' (longer cotton) Staple length US'' + 1/16'' = EL'' (shorter cotton) Staple length US'' = 0.91 × EL'' Staple length Uk''- 1/32'' = EL'' (long staple) Staple length Uk'' + 1/32'' = EL'' (medium staple) Mean length (x 1/8) in. = (Sum of base line readings / Base line length) = (453.2 / 64) = 7.1 Mean length (x 1/32 in.) = 4 x 7.1 = 28.4
Photoelectric method (Fibro graph): • Optical method of measuring the density along the length of a tuft of parallel fibres. • Samples are prepared by “fibro sampler”.
FIBER LENGTH
FIBER LENGTH
• The point where it is caught is at random along its length. • Distance traveled from base line • Floating fibre (%) = [2.5%SL / L – 0.975} × 100 • U.R. = (50%SL / 2.5% SL) × 100 [apprx. 40-50% for normal cotton] • Where L = avg. length of fibre
Shirley photoelectric stapler: • For quicker measurement of length (staple length). • Objective measuring technique of earlier staple length measuring method. (Classer judges by eye).
FIBER LENGTH
WIRA MACHINE : The WIRA fibre length machine [13] is an attempt to automate the proces of single fibre measurement and is intended mainly for measuring wool fibres. The equipment shown in Fig. 3.11 involves a rotating shaft with a spiral groove machined in it. One end of the fibre to be measured is gripped by a pair of tweezers whose point is then placed in the moving spiral. This has the effect of moving the tweezers to the right and so steadily drawing the fibre through the pressure plate. This ensures that the fibre is extended under a standard tension. A fine wire rests on the fibre and is arranged so that when the far end of the fibre passes under the wire it allows it to dropinto a small cup of mercury and thus complete an electrical circuit.
causes the shaft to stop moving, so halting the tweezers; at this point the tweezers are then raised to lift the counter immediately above where it has stopped. The counters are arranged in 0.5 cm sections and each time one is lifted it adds a unit to the appropriate length group so contributing to a cumulative total.
FIBER LENGTH
THANK YOU

More Related Content

FIBER LENGTH

  • 2. Why fibre length? • Quality assessment, Fibre breakage study, machine settings, combing efficiency, etc. • Length of staple fibre is one of the most important characteristics. In general a longer average fibre length is to be preferred because it confers a number of advantages. Firstly, longer fibres are easier to process. Secondly, more even yarns can be produced from them because there are less fiber ends in a given length of yarn. Thirdly, a higher strength yarn can be produced from them for the same level of twist. • The length and fineness are sometimes related in natural fibres whereas for man-made fibres, length and fineness can be controlled separately.
  • 3. DEFINITIONS OF FIBRE LENGTH PARAMETRES:- • Mean length : The arithmetic mean of the length of all the fibres present in a small but representative sample of cotton, based on weight-length distribution or relative number-length distribution. • Upper Quartile Length: The length for which 75 per cent of all the observed values are lower and 25 per cent higher, by weight or by number
  • 4. • Effective Length : It is difficult to give a clear scientific definition for effective length. It may be defined as the upper quartile of the numerical length distribution from which some of the shortest fibres are eliminated by an arbitrary construction. The fibres eliminated are those shorter than half the effective length. • Span Length : The distance spanned by a specified percentage of the fibres in the test beard. 2.5% span length is the distance from the clamp on a fibre beard to a point upto which only 2.5% of the fibres extend.
  • 5. MEASUREMENT OF FIBRE LENGTH :- • 1. HAND STAPLING METHOD. • 2. COMB SORTER METHOD. • 3. PHOTO ELECTRIC METHOD (FIBRO GRAPH). • 4. SHIRLEY PHOTO ELECTRICAL METHOD. • 5. WIRA FIBRE LENGTH MACHINE.
  • 6. HAND STAPLING METHOD : (By trained classers) • Selecting a sample and preparing the fibres by hand doubling and drawing to give a fairly well straightened tuft of about ½ inch wide. • This is laid on flat black background and the staple length is measured. • The shorter fibres will lie in body of the tuft and extreme ends (tips) will not be the limits used for measurement of staple length. • The classer chooses the length where there are reasonably well defined edges • Subjective in nature, so difference in results between classers.
  • 8. In the diagram OQ = 1/2 OA OK = 1/4 OP KS = 1/2 KK’ OL = 1/4 OR Short fibre percentage = (RB/OB) × 100% LL’ = Effective length (because many m/c settings are related with this length) LL’-MM’ = NL’=Inter-quartile range Dispersion% = NL’/LL’ (For flatter middle zone, dispersion is minimum) Frequency distribution in opposite way, i.e. the curve is known but the frequency distribution is to be obtained.
  • 10. Comb sorter diagram analysis: Staple length US'' + 3/32'' = EL'' (34/32'' - 39/32'') Staple length US''+ 1/8'' = EL'' (longer cotton) Staple length US'' + 1/16'' = EL'' (shorter cotton) Staple length US'' = 0.91 × EL'' Staple length Uk''- 1/32'' = EL'' (long staple) Staple length Uk'' + 1/32'' = EL'' (medium staple) Mean length (x 1/8) in. = (Sum of base line readings / Base line length) = (453.2 / 64) = 7.1 Mean length (x 1/32 in.) = 4 x 7.1 = 28.4
  • 11. Photoelectric method (Fibro graph): • Optical method of measuring the density along the length of a tuft of parallel fibres. • Samples are prepared by “fibro sampler”.
  • 14. • The point where it is caught is at random along its length. • Distance traveled from base line • Floating fibre (%) = [2.5%SL / L – 0.975} × 100 • U.R. = (50%SL / 2.5% SL) × 100 [apprx. 40-50% for normal cotton] • Where L = avg. length of fibre
  • 15. Shirley photoelectric stapler: • For quicker measurement of length (staple length). • Objective measuring technique of earlier staple length measuring method. (Classer judges by eye).
  • 17. WIRA MACHINE : The WIRA fibre length machine [13] is an attempt to automate the proces of single fibre measurement and is intended mainly for measuring wool fibres. The equipment shown in Fig. 3.11 involves a rotating shaft with a spiral groove machined in it. One end of the fibre to be measured is gripped by a pair of tweezers whose point is then placed in the moving spiral. This has the effect of moving the tweezers to the right and so steadily drawing the fibre through the pressure plate. This ensures that the fibre is extended under a standard tension. A fine wire rests on the fibre and is arranged so that when the far end of the fibre passes under the wire it allows it to dropinto a small cup of mercury and thus complete an electrical circuit.
  • 18. causes the shaft to stop moving, so halting the tweezers; at this point the tweezers are then raised to lift the counter immediately above where it has stopped. The counters are arranged in 0.5 cm sections and each time one is lifted it adds a unit to the appropriate length group so contributing to a cumulative total.