Industrial Engineering Formulas for Textile Students and Professionals

Industrial Engineering Formulas for Textile Students and Professionals
Joyankar Mojumder
Executive-IE, Paddocks Jeans Ltd.
DEPZ, Savar, Dhaka.
Mob: 01813171408
Email: mozumderjoy@yahoo.com


Industrial Engineering:
Industrial engineering is a branch of engineering which studies the design and operation of production and service systems and the people who operate in these systems. Industrial engineering helps to improve quality and productivity. It is said that without industrial engineering operations is like meal without salt and if you use operation management instead of production management it will be best.

We can see at a glance of IE,

Industrial Engineering (IE) = Production ↑ Cost ↓ Proper use of all elements ↑ Efficiency ↑ Profit ↑

Some Important Formula for Industrial Engineering:
Some important formula of industrial engineering are given below for textile and apparel students and professionals.


                                                     Sum of average
1. Average time (in minute) = ……………………………………… ÷ 60
                                             π‘π‘’π‘šπ‘π‘’π‘Ÿ π‘œπ‘“ π‘œπ‘π‘ π‘’π‘Ÿπ‘£π‘Žπ‘‘π‘–π‘œπ‘›

2. Normal time = Average cycle time × Rating.

3. SMV =Observe time × Rating + Allowance.

                                            π‘‡π‘œπ‘‘π‘Žπ‘™ π‘œπ‘’π‘‘π‘π‘’π‘‘ ×Oπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘–π‘œπ‘› 𝑆𝑀𝑉
4. Individual OP efficiency = ……………………………………….. ×100
                                                π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘–π‘›π‘” π‘šπ‘–π‘›π‘’π‘‘π‘’

                                        π‘‡π‘œπ‘‘π‘Žπ‘™ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘–π‘œπ‘› × π‘†π‘€π‘‰
5. Efficiency % = ………………………………………………… ×100
                         π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘–π‘›π‘” π‘šπ‘–π‘›π‘’π‘‘π‘’ ×π‘‡π‘œπ‘‘π‘Žπ‘™ π‘šπ‘Žπ‘›π‘π‘œπ‘€π‘’π‘Ÿ

                                           π‘‡π‘œπ‘‘π‘Žπ‘™ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑋 𝑆𝑀𝑉
6. Performance = ……………………………………..............……………. X 100
                         (π‘€π‘Žπ‘›π‘π‘œπ‘€π‘’π‘Ÿ ×π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘–π‘›π‘” π‘šπ‘–π‘›π‘’π‘‘π‘’)−πΏπ‘œπ‘ π‘  π‘‘π‘–π‘šπ‘’

                                            π·π‘’π‘Ÿπ‘–π‘›π‘” π‘–π‘›π‘‘π‘’π‘Ÿπ‘£π‘’π‘›π‘‘π‘–π‘œπ‘› 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦−π΅π‘Žπ‘ π‘’ 𝑙𝑖𝑛𝑒 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦
7. Efficiency Improvement = ………………………………………………........………… x 100
                                                                 π΅π‘Žπ‘ π‘’ 𝑙𝑖𝑛𝑒 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

8. Total labor cost saved per line = Extra minute produce × cost per SAM.

                                                                                  60
9. Worker potential production per hour = …………………………
                                                                     π΅π‘Žπ‘ π‘–π‘ π‘šπ‘–π‘›π‘’π‘‘π‘’ π‘£π‘Žπ‘™π‘’π‘’

                                                                 60
10. Individual worker target per hour = ……. × π‘Šπ‘Žπ‘›π‘‘π‘’π‘‘ 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦
                                                               𝑆𝑀𝑉

                                             60
11. Line target per hour = ………… ×(π‘€π‘Žπ‘›π‘π‘œπ‘€π‘’π‘Ÿ ×π‘Šπ‘Žπ‘›π‘‘π‘’π‘‘ 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦)
                                          𝑆𝑀𝑉

                                                           π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ 𝑑𝑒𝑓𝑒𝑐𝑑 𝑒𝑛𝑖𝑑
12. Defect of hundred unit (DHU) = ……………………………… x 100
                                                           π‘‡π‘œπ‘‘π‘Žπ‘™ π‘–π‘›π‘ π‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑒𝑛𝑖𝑑

                               π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ 𝑑𝑒𝑓𝑒𝑐𝑑 𝑒𝑛𝑖𝑑
13. Defective % = …………………………………… x 100
                                π‘‡π‘œπ‘‘π‘Žπ‘™ π‘–π‘›π‘ π‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑒𝑛𝑖𝑑

                                                                                      π‘‡π‘œπ‘‘π‘Žπ‘™ π‘œπ‘’π‘‘π‘π‘’π‘‘
14. Productivity each person per hour = …………………………………………. x 100
                                                                 π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘’π‘Ÿ ×π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘–π‘›π‘” π‘šπ‘–π‘›π‘’π‘‘π‘’

                                                             π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑒𝑛𝑖𝑑𝑠 π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘’ 𝑏𝑦 π‘‘β„Žπ‘’ 𝑙𝑖𝑛𝑒
15. Machine productivity = ………………..............................………………………..
                                             π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ π‘šπ‘Žπ‘β„Žπ‘–π‘’π‘› 𝑒𝑠𝑒 π‘‘π‘œ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘’ π‘‘β„Žπ‘œπ‘ π‘’ π‘”π‘Žπ‘Ÿπ‘šπ‘’π‘›π‘‘π‘ 

                                          π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑆𝑀𝑉
16. Basic pitch time = ………………………………
                                    π‘‡π‘œπ‘‘π‘Žπ‘™ π‘šπ‘Žπ‘›π‘π‘œπ‘€π‘’π‘Ÿ

                                                       π΅π‘Žπ‘ π‘–π‘ π‘π‘–π‘‘π‘β„Ž π‘‘π‘–π‘šπ‘’
17. Upper control limit = …………………………………………
                                         π‘Šπ‘Žπ‘›π‘‘π‘’π‘‘ π‘œπ‘Ÿgπ‘Žπ‘›π‘–π‘§π‘Žπ‘‘π‘–π‘œπ‘› 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

18. Lower control limit = (Basic pitch time × 2) – π‘ˆπ‘π‘π‘’π‘Ÿ π‘π‘œπ‘›π‘‘π‘Ÿπ‘œπ‘™ π‘™π‘–π‘šπ‘–π‘‘

                                       π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑐𝑒𝑑 π‘žπ‘’π‘Žπ‘›π‘‘π‘–π‘‘π‘¦ - π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ β„Žπ‘–π‘ π‘žπ‘’π‘Žπ‘›π‘‘π‘–π‘‘π‘¦
19. Cut of ship loss % = …………………………………...……..…… ×100
                                                     π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑐𝑒𝑑 π‘žπ‘’π‘Žπ‘›π‘‘π‘–π‘‘π‘¦

                                     π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ β„Žπ‘–π‘π‘π‘’π‘‘ π‘žπ‘’π‘Žn𝑑𝑖𝑑𝑦
20. Cut of ship ratio = ………………………………………. ×100
                                      π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑐𝑒𝑑 π‘žπ‘’π‘Žπ‘›π‘‘π‘–π‘‘π‘¦

                                                              𝑁𝑒𝑀 𝑐𝑒𝑑 π‘‘π‘œ π‘ β„Žπ‘–π‘ π‘Ÿπ‘Žπ‘‘π‘–π‘œ−π΅π‘Žπ‘ π‘’ 𝑙𝑖𝑛𝑒 π‘Ÿπ‘Žπ‘‘π‘–π‘œ
21. Cut of ship ratio improvement % = …………………..…………………………..×100
                                                                               π΅π‘Žπ‘ π‘’ 𝑙𝑖𝑛𝑒 π‘Ÿπ‘Žπ‘‘π‘–π‘œ

                                                           π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ β„Žπ‘–π‘ π‘žπ‘’π‘Žπ‘›π‘‘π‘–π‘‘π‘¦
22. Receive to ship ratio = …………........................………………………… ×100
                                            π‘‡π‘œπ‘‘π‘Žπ‘™ π‘“π‘Žπ‘π‘Ÿπ‘–π‘ π‘Ÿπ‘’π‘π‘’π‘–π‘£π‘’ π‘“π‘œπ‘Ÿ π‘‘β„Žπ‘’ π‘œπ‘Ÿπ‘‘π‘’π‘Ÿ (π‘†π‘ž.𝑦𝑑𝑠)

23. Total financial saving = Number of extra pieces shipped × Average FOB

                                                   π΄π‘£π‘’π‘Ÿπ‘Žπ‘”π‘’ 𝑒π‘₯𝑝eπ‘›π‘‘π‘–π‘‘π‘’π‘Ÿπ‘’ π‘œπ‘“ π‘‘β„Žπ‘’ π‘“π‘Žπ‘π‘‘π‘œπ‘Ÿπ‘¦
24. Cost Per Minute (CPM) = …………………………............………………..
                                                    π΄π‘£π‘’π‘Ÿπ‘Žπ‘”π‘’ π‘ƒπ‘Ÿπ‘œπ‘‘π‘’π‘π‘’ π‘‘π‘–π‘šπ‘’ (π‘€π‘œπ‘›π‘‘β„Žπ‘™π‘¦)

25. Cost of Manufacture (CM) = SMV × CPM

                                                                  π‘‡π‘œπ‘‘π‘Žπ‘™ π‘œπ‘’π‘‘π‘π‘’π‘‘ ×𝐢𝑀 π‘π‘’π‘Ÿ π‘”π‘Žπ‘Ÿπ‘šπ‘’π‘›π‘‘π‘ 
26. CM earned per person per hour = ………………….....………………………….
                                                               π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘’π‘Ÿ ×π‘‡π‘œπ‘‘π‘Žπ‘™ π‘€π‘œπ‘Ÿπ‘˜π‘–π‘›π‘” π‘šπ‘–π‘›π‘’π‘‘π‘’

27. Monetary Loss due to cut ship loss in month = (Total number of produced garments in month × cut to ship loss percentage for a month × Average FOB of the style)

28. Monetary Loss due to cut ship loss in style wise = (Total number of produced garments in the style × cut to ship loss percentage for a month × Average FOB of the style)

                                                π‘‡π‘œπ‘‘π‘Žπ‘™ π‘šπ‘Žπ‘›π‘π‘œπ‘€π‘’π‘Ÿ
29. Man & machine ratio = ……………………………………
                                               π‘‡π‘œπ‘‘π‘Žπ‘™ π‘šπ‘Žπ‘β„Žπ‘–π‘›π‘’

                              π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ π‘Žπ‘’π‘‘π‘–π‘‘ π‘“π‘Žπ‘–π‘™
30. Audit fail % = ………………………………….×100
                                π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ π‘Žπ‘’π‘‘π‘–π‘‘

31. Earned minute = Total production X SAM

                                                            π‘‡π‘œπ‘‘π‘Žπ‘™ β„Žπ‘’π‘Žπ‘‘π‘π‘œπ‘’π‘›π‘‘−π‘π‘œ π‘œπ‘“ π‘šπ‘Žπ‘β„Žπ‘–π‘›π‘’ π‘œπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘œπ‘Ÿπ‘ 
32. Factory direct & indirect ratio = …………………………………………………….
                                                                            π‘‡π‘œπ‘‘π‘Žπ‘™ π‘›π‘œ π‘œπ‘“ π‘œπ‘π‘’π‘Ÿπ‘Žπ‘‘π‘œπ‘Ÿπ‘ 

                                                      π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ π‘Žπ‘™π‘Žπ‘Ÿπ‘¦ π‘œπ‘“ π‘‘β„Žπ‘’ π‘™π‘Žπ‘π‘œπ‘Ÿ 𝑖𝑛 π‘‘β„Žπ‘’ π‘šπ‘œπ‘›π‘‘β„Ž
33. Labor cost per minute = ……………........……………………………………….
                                               π‘‡π‘œπ‘‘π‘Žπ‘™ 𝑆𝐴𝑀 π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘’ 𝑏𝑦 π‘‘β„Žπ‘œπ‘ π‘’ π‘™π‘Žπ‘π‘œπ‘Ÿπ‘  𝑖𝑛 π‘‘β„Žπ‘Žπ‘‘ π‘šπ‘œπ‘›π‘‘β„Ž

                                                            π‘π‘œ π‘œπ‘“ π‘šπ‘Žπ‘β„Žπ‘–π‘›π‘’ π‘Žπ‘ π‘ π‘–π‘”π‘›π‘’π‘‘ ×π»π‘œπ‘’π‘Ÿπ‘™π‘¦ π‘‘π‘Žπ‘Ÿπ‘”π‘’π‘‘ π‘žπ‘‘y
34. Estimated production per hour = …………………………………………………………….
                                                                        πΆπ‘Žπ‘™π‘π‘’π‘™π‘Žπ‘‘π‘’π‘‘ π‘›π‘œ π‘œπ‘“ π‘šπ‘Žπ‘β„Žπ‘–π‘›π‘’π‘ 

                                                              π‘‡π‘œπ‘‘π‘Žπ‘™ π‘šπ‘–π‘›π‘’π‘‘π‘’ 𝑖𝑛 π‘Ž π‘ β„Žπ‘–π‘“π‘‘ ×𝐿𝑖𝑛𝑒 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦
35. Estimated machine productivity = ………………………………………………………..
                                                                                 πΊπ‘Žπ‘Ÿπ‘šπ‘’π‘›π‘‘π‘  𝑆𝑀𝑉

                                         π‘Šπ‘œπ‘Ÿπ‘˜π‘’π‘Ÿ π‘π‘œπ‘‘π‘’π‘›π‘‘π‘–π‘Žπ‘™ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑃.𝐻 - πΆπ‘’π‘Ÿπ‘Ÿπ‘’π‘›π‘‘ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑝𝑐𝑠 𝑃.𝐻
36. Productivity Gap % = ………………….……………..................………………………… ×100
                                                          πΆπ‘’π‘Ÿπ‘Ÿπ‘’π‘›π‘‘ π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘–π‘œπ‘› 𝑝𝑐𝑠 π‘π‘’π‘Ÿ β„Žπ‘œπ‘’π‘Ÿ

Friction in Textile Fibers and Its Effect in Fiber Processing

FRICTIONAL PROPERTIES OF TEXTILE FIBER
Ali Rayhan Sarkar 
B.Sc. in Textile Engineering
Daffodil International University
Email: alirayhansarkar3268@diu.edu.bd



Introduction:
Friction is the force that resists the movement of a surface over another surface during sliding. When the textile materials are processed, then friction is developed between the fibers. The properties which are shown by a textile material during friction is known as frictional property. This properties are shown during processing. Too high friction and too low friction is not good for yarn. Therefore it is an important property when yarn manufacturing and processing. 
 
There are two types of friction.
  1. Static friction: The force that must be overcome in order to start sliding is called static friction.
  2. Kinetic friction: The force that resists continued sliding is known as kinetic friction.
Frictional properties depend on:
  1. Composition of the material
  2. State of the surface of the material
  3. Pressure between the surfaces
  4. Temperature
  5. Relative humidity %
  6. Area of contact
  7. Water absorption of fiber
Co-efficient of friction:
Frictional force is proportional to the normal or perpendicular of a material due to its own weight. 
 
That is, F ∞ N Or, F = ΞΌ N Or, ΞΌ = F/N 
 
Where, F = Frictional force, N = Normal / perpendicular force. Here, ΞΌ is the proportional constant known as “co-efficient of friction”. So, co-efficient of friction can be defined as the ratio of frictional force and perpendicular force.

Methods of measuring co-efficient of friction:

Capstan method is most commonly used to measure co-efficient of fraction. Capstan method can be classified into two classes-
  1. Static capstan method
  2. Dynamic capstan method
Other methods-
  1. Buckle & Pollitt’s method
  2. Abboh & Grasberg method
  3. Gutheric & Olivers method
Frictional properties influences:
In fiber stage
  1. The behavior of fiber during drafting.
  2. The frictional force holds together the fiber in yarn, i.e, frictional force helps to spun the fiber to yarn.
In yarn stage
  1. If the frictional force is too low, yarn strength will be low.
  2. Friction increases the luster and smoothness of yarn.
  3. Friction makes more clean yarn.
  4. Friction increases hairiness.
  5. Friction occurs nep formation.
In fabric stage
  1. Fabric feelings varied for difference between static and kinetic friction.
  2. Fabric will be slippery if Β΅s >Β΅k is high. Fabric will be harsh if Β΅s >Β΅k is low.
    Here, Β΅s= Co- efficient of static friction, Β΅k= Co-efficient of kinetic friction.
  3. If the frictional force is high the handle properties of fabric quality will be low.
  4. High static friction causes high breakage of yarn in weaving.
Factors affecting frictional intensity:
  1. Load: If load increases frictional intensity will also increase.
  2. Area of contact or angle of contact: Frictional intensity increases with the increasing of angle of contact.
  3. Speed of sliding: More speed of sliding causes more frictional intensity.
  4. The state of surface: The frictional force is changed if the surface is lubricated either naturally or artificially or has been contaminated by dirt or impurities. The frictional force increases both as the oil content is increased and as the viscosity of the oil increases.
  5. Effect of absorbed water: The frictional force usually increases as the regain of the fibre is raised.
Importance of friction in Textile Industry:
  1. Friction holds the fibre in a sliver and hence material does not break due to self weight.
  2. Friction helps in drafting and drawing process.
  3. Uniform tension can be maintained in winding and warping because of friction.
  4. Friction helps in twisting during spinning.
  5. Friction modifies the luster and appearance of a cloth.
  6. Friction makes more clean yarn.
Demerits of friction on textile material:
  • Friction causes nap formation. 
  • High static friction causes high breakage of yarn during weaving.
  • If the frictional force is high, the handle properties of fabric will be low.
  • Friction generates temperature and therefore static electricity is developed which attracts dust, dirt etc. and the materials become dirty.
  • Sometimes due to over friction materials may be elongated.
  • Friction increases yarn hairiness. 
  • Friction worn out parts of machine.
Friction in textile material
Friction in textile material
Minimization of friction intensity:

1. By processing with lubricates:
Lubricating material as emulsion is used before jute spinning. Sizing is done during weaving preparation process. It also reduces yarn damage. Emulsion, oil, lubricants are applied specially on jute fibre to reduce friction.

2. By chemical treatment:

By using acid or alkali. Acid or alkali is done on wool fibre to reduce scale sharpness and thus frictional intensity.

3. By finishing process:
  • Mechanical finishing: Ironing of calendaring.
  • Chemical finishing: By using resin. Resin is one typed anti-crease agent because it prevents fibre from creasing by blocking hydroxyl groups.
  • By using softener we can minimize frictional intensity.
Theories of friction in textiles:
In this section, the various theories proposed for friction in textiles are reviewed. Kragelskii divided friction theories into four groups, as follows: friction is a result of (i) lifting asperities over one another (ii) overcoming the forces of molecular interaction; (iii) displacing a volume of material (ploughing); and (iv) at least two components contributing to friction, i.e. composite theories.

The adhesion theory of friction has been the basis of explanation for friction in fibrous materials.

Arrows are vectors indicating directions and magnitudes of forces (Figure 1). W is the force of weight, N is the normal force, F is an applied force, and Ff is the force of kinetic friction, which is equal to the coefficient of kinetic friction times the normal force. Since the magnitude of the applied force is greater than the magnitude of the force of kinetic friction opposing it, the block is accelerating to the left.

Yarn friction

Factors affecting yarn friction Overview:
Yarn friction is related to both surface properties and bulk properties of yarns. There are four main groups of factors: (i) Fibre parameters; (ii) Yarn structural and bulk parameters; (iii) Operational parameters; and (iv) Finishes. Fibre parameters include fibre structural and bulk parameters. Yarn structural and bulk parameters include yarn twist, spinning method, yarn denier, etc. Operational parameters consist of normal load, frictional speed, humidity, temperature, sliding speed, measuring method, contact geometry, and the like. The effect of finishes depends on the nature, the viscosity, and the content of lubricant, etc.

Yarn friction has been investigated in relation to fibre parameters; yarn structural parameters, operational parameters, and finishes, including lubricants.

Effects of fibre parameters:
Fibre Surface Roughness: It has been observed that with an increase in roughness of the fibre surface, final tension and hence friction in the yarn increases (Table 1).

Table 1: Effect of fibre surface roughness on yarn friction
Continuous filament yarn sample tested
Initial tension (gm)
Final tension (gm)


Smooth
Rough
Yarn to metal test
25
60
40
Yarn to yarn test
15
41
31
 

Molecular Orientation:
Gupta and El Mogahzy investigated the effect of molecular orientation on the friction of acrylic yarns. Inter-fibre friction and molecular orientation at the fibre surface, characterised by a sonic modulus orientation factor, increased with draw ratio. They found a strong correlation between molecular orientation of the fibre and inter-fibre friction. More intimate or greater area of contact by smoothing out of the surface for a more highly oriented fibre may be responsible for this finding.

Table 2: Orientation factor and Coefficient of Friction (Β΅) of acrylic yarns at different values of cascade stretch (Xc.s)
Sample no
Xc.s
Orientation factor
Β΅, Point contact
Β΅, Line contact
1
2.0
0.6949
0.135
0.186
2
3.0
0.7316
0.136
0.221
3
4.0
0.7556
0.134
0.230
4
5.0
0.7725
0.138
0.235
5
6.0
0.7847
0.138
0.238
6
7.0
0.7918
0.141
0.243










Effects of yarn structural and bulk parameters:
Yarn denier: The fineness (denier) has an increasing effect on friction due to an increase in the area of contact. Kalyanaraman observed that the coefficient of friction of yarn increased with increasing yarn linear density, due to the larger contact area, using the SITRA friction measuring device.

Yarn twist: Chattopadhyay and Banerjee found that, with increasing yarn twist of ring and rotor spun yarns, friction decreased for cotton, viscose rayon, and polyester yarns. In this study, the material and processing parameters selected were Yarn linear density = 59 tex, Relative Speed = 40 m/min., Input Tension = 11 cN. and Number of wraps = 2. Higher twist decreases compressibility, resulting in a smaller area of contact and thus lower frictional force. Higher twist showed greater friction for cotton ring spun yarns. Subramaniam and Natarajan found that the coefficient of friction of siro spun yarns increased with increasing strand spacing and twist. This result was attributed to the nature of the yarn surfaces.

Spinning method: Chattopadhyay and Banerjee studied the effects of spinning method on yarn-to-yarn and yarn-to-guide friction, using ring, rotor and friction spun yarns for cotton, polyester and viscose rayon. The effects of spinning method on yarn to-guide friction depend on the frictional speed and material type. Yarn surface structural characteristics, eg, belt fibres of rotor yarns, and compressibility were considered as important factors affecting yarn friction.

From the results, it may be observed that. For both cotton and viscose fibres, ring spun yarn shows the maximum frictional force and tension ratio, followed by rotor and friction spun yarns, which are close to each other. The results are therefore just the reverse of what was observed for friction between yarns. The order in which the magnitude of the friction changes for cotton and viscose fibre is therefore different in two cases and shown below:

Between yarns: friction-spun > rotor-spun > ring-spun
Between yarn and guide: ring-spun > rotor-spun > friction-spun
 
In above study, the material and processing parameters selected were Yarn linear density = 98.4 tex. Input Tension = 12 cN. In case of polyester fibre, friction spun yarn shows the highest value, followed by rotor- and ring-spun yarns. The order in which the friction changes is therefore just the reverse of what is observed for cotton and viscose fibres.

Yarn surface roughness: Yarn roughness was increased by insertion of twist in a multifilament yarn and by incorporation of titanium dioxide. The yarn friction decreased with increased roughness of the yarn surface. However, for a very rough yarn surface, the yarn friction tended to increase owing to the Coulomb component.

Unevenness: Unevenness of yarn tends to influence the frictional forces. As yarn unevenness increases, frictional force becomes greater.
 
Effects of operational parameters:
Pretension: An increase in pretension results in an increase in friction. This may be because the increase in pressure with pretension causes an increase in the area of contact and thus an increase in friction. 
 
The coefficient of friction between silk filaments and steel is reduced from 0.44 to 0.27 (along the fibre) and 0.34 and 0.23 (across the fibre) with increasing yarn tension from 5 to 20 cN at a specified angle of wrap. 
 
Sliding Speed: The increase in the friction of spun yarns with increasing speed may be attributed to the fact that, at high-speeds, the hairs may bend down owing to the pull of the yarn, leading to an increase in the contact area.

With increase in speed, the friction coefficient of cotton, rayon, and silk yarns increases when measured by the capstan method.

The friction of ring, rotor and friction spun yarn decreases with increasing frictional speed from 40 to 200 m/min. In this study, the material and processing parameters selected were Yarn linear density = 98.4 tex. Input Tension = 11 cN. Number of wraps = 2.

Temperature: The effects of temperature on yarn friction have been related to the thermal conductivity of guide materials.

The effect of guide temperature on friction should be considered along with speed. Thermally stable lubricants are required to prevent melting of fibres at the fibre-to-metal surface, due to high temperature. For the effect of temperature, the initial decrease in friction with increasing temperature may be attributed to the decrease in lubricant viscosity, and subsequent increase in friction to volatilisation and/or thermal decomposition of lubricant causing softening of the polymer surface.

Humidity: The effects of relative humidity and moisture content of yarns on friction affect yarn breakage rates and the quality of products. The coefficient of friction of yarn was reported to increase with increase in humidity and sharply increase above 80% relative humidity.

Effects of Finishes:

General: In this section, the effects of finishes including lubricants and softeners, and finishing such as mercerization, plasma etching and laser irradiation are discussed.

Lubricants: The action of a lubricant is to (a) reduce the abrasion of fibres, yarns and machine parts, (b) reduce static electrification during textile processing, and (c) ensure adequate strength of spun yarns and their final products. A lubricant has been found to have a pronounced effect on both yarn-to-metal and yarn-to-yarn friction. Under boundary lubrication, friction is governed by the chemical nature of lubricants and the sliding surfaces, the shear strength of the lubricants, the rigidity of the substrates, and the pressure at the areas of contact.

Lubricants reduced friction of spun yarns by reduction in friction index a. The index n remained constant either with the type or concentration of lubricants. Lubrication of the yarn gradually reduced the coefficient of friction. This trend was more pronounced when the lubricant or the surface active agent was deposited at the interface, as in dry treatment studies, rather than when it was present in solution, as in the case of submerged experiments.

Softeners: Sebastian, et al reported that treatment with cationic softening agents reduced inter-yarn sliding friction.

Mercerization: The effects of slack mercerization, using zinc chloride, on yarn properties of ring and open-end spun cotton yarns have been investigated. The coefficient of friction of yarns increased after mercerization.

Plasma etching: The effect of plasma etching on frictional properties of polyester filaments has been investigated. Plasma treatment increased the roughness of fibre surface and caused an increase in inter-fibre friction and fibre cohesion.

Laser Irradiation: By laser irradiation of polyester yarn surfaces during a continuous winding process, the friction between the yarns and the guiding elements was reduced. 
 
Lubrication of yarns:
Purpose: Lubrication of yarn is critical to knitting yarns and sewing threads for their processing performance-to provide low levels of friction (Table 7), and for protection from heat generated by the needle. Fabric and garment manufacturing require good yarn lubrication.

Lubricants can modify both the surface and the bulk of yarn. For yarn, depending on its molecular size and charge, the lubricating agent may deposit itself on the yarn surface, or penetrate the yarn and deposit on the surface of the individual fibre.

Applications:
Friction is an important factor in many engineering disciplines. 
 
Transportation:
  1. Rail adhesion refers to the grip wheels of a train have on the rails, see Frictional contact mechanics.
  2. Road slipperiness is an important design and safety factor for automobiles
  3. Split friction is a particularly dangerous condition arising due to varying friction on either side of a car.
  4. Road texture affects the interaction of tires and the driving surface.
Laws of friction:
  1. The frictional force is independent of the area of contact between two surfaces.
  2. The frictional force “F” is proportional to the normal reaction “RN”.
  3. This law is known as Coulomb’s law and friction’s third law. Kinetic force is independent of the speed of sliding.
Measurement of friction:
Methods of friction measurement can be divided into two classes. They are – 
 
1. Frictional at only one point of contact.
  • Between two different fibres.
  • Between two different fibres.
  • Between a fibre and non-fibre materials such as metal, plastic and ceramic.
2. Average friction at a great number of contacts.

Conclusions :
Friction is the resistance to movement of one body over body. The word comes to us from the Latin verb fricare, which means to rub. The bodies in question may be a gas and a solid (aerodynamic friction), or a liquid and a solid (liquid friction); or the friction may be due to internal energy dissipation processes within one body (internal friction). In this article, the discussion will be limited to the effects of solid friction. Two of the most significant inventions of early man are friction-related: He learned to use frictional heating to start his cooking fires, and he discovered that rolling friction is much less than sliding friction (that is, it is easier to move heavy objects if are on rollers than it is to drag them along). This second discovery would eventually lead to the invention of the wheel. 
 
Friction plays an important role in a significant number of our daily activities and in most industrial processes. It aids in starting the motion of a body, changing its direction, and subsequently stopping it. Without friction, we could not readily move about, grip objects, light a match, or perform a multitude of other common daily tasks. Without friction, most threaded joints would not hold, rolling mills could not operate, and friction welding would obviously not exist. Without friction, we would hear neither the song of the violin nor the squeal of the brake. In moving machinery, friction is responsible for dissipation and loss of much energy. It has been estimated, for example, that 10% of oil consumption in the United States is used simply to overcome friction. The energy lost to friction is an energy input that must continually be provided in order to maintain the sliding motion. This energy is dissipated in the system, primarily as heat—which may have to be removed by cooling to avoid damage and may limit the conditions under which the machinery can be operated. Some of the energy is dissipated in various deformation processes, which result in wear of the sliding surfaces and their eventual degradation to the point where replacement of whole components becomes necessary.

Different Parts and Features of Ring Traveller

Different Parts and Features of Ring Traveller
Dipak Baraiya
Dept.of Textile Technology
Maharaja Saiyajirao University, Baroda, India
Cell: +91 9687780158
Email: dipakbaraiya9013@gmail.com



Ring traveler:
Ring traveler is the most tinny and simple mechanical element in ring frame. It has a direct effect on the quality of yarn produced as their action physically turns the raw material into finished product. So, ring traveller plays very important role in ring spinning system.
Ring traveler
Fig: Ring traveler
Functions of Ring traveler:
  1. Imparts twist to the yarn and
  2. It is responsible for winding the yarn onto the cop.
  3. It defines Spinning tension.
  4. It defines Winding Tension.
  5. Traveller imparts twist to the yarn.
  6. Traveller and spindle together help to wind the yarn on the bobbin. Length wound up on the bobbin corresponds to the difference in peripheral speeds of the spindle and traveller. The difference in speed should correspond to length delivered at the front rollers. Since traveller does not have a drive on its own but is dragged along behind by the spindle.
Various Parts of Ring Traveller:

Toe gap: This will vary according to traveller number and flange width of the ring.
Toe gap
Height of bow: It should be as low as possible for stable running of traveller. It should also have sufficient yarn passage.
Height of bow
Height of bow
Ring contact area: This area should be more, uniform, smooth and continuous for best performance.
Ring contact area
Inner width: This varies according to traveller profile and ring flange.
Inner width
Wire section: It plays an important role for yarn quality, life of traveller.
Wire section
Yarn passage: According to count spun the traveler profile to be selected with required yarn passage.
Yarn passage
Salient Features of a Ring Traveller:
  1. Generate Less Heat .
  2. Dissipate Heat Fast.
  3. Have Sufficient Elasticity For Easy Insertion And To Retain Its Original Shape After Insertion.
  4. Friction Between Ring And Traveller Should Be Minimal.
  5. It Should Have Excellent Wear Resistance For Longer Life.
  6. Hardness Of The Traveller Should Be Less Than The Ring .
Traveller Speed: 
The speed by which the traveller moves around the ring = Ξ  DR NT m/min
  • Since traveller does not have a drive on its own but is dragged along behind by the spindle. High contact pressure (up to 35 N/ mm2)is generated between the ring and the traveller during winding, mainly due to centrifugal force. 
  • This pressure leads to generation of heat. Heat produced when by the ring traveller is around 300 degree celcius. This has to be dissipated in milliseconds by traveller into the air. 
  • Low mass of the traveller does not permit dissipation of the generated heat in the short time available. As a result the operating speed of the traveller is limited. 
  • The maximum attainable speed of traveller without getting damaged is known as “Limiting Speed of Traveller”. 
  • 70 ft/sec. (22 m/sec) – Conventional Ring- traveller. 
  • 120 ft/sec. (35 m/sec) – H.S. Ring- traveller.
Limitations of Ring –Traveller Spinning System
  • When the spindle speed is increased, the friction work between ring and traveller increases as the 3rd power of the spindle rpm. Consequently if the spindle speed is too high, the traveller sustains thermal damage and fails. This speed restriction is felt particularly when spinning cotton yarns of relatively high strength. 
  • If the traveller speed is raised beyond normal levels , the thermal stress limit of the traveller is exceeded, a drastic change in the wear behaviour of the ring and traveller ensues. Owing to the strongly increased adhesion forces between ring and traveller, welding takes place between the two. These seizures inflict massive damage not only to the traveller but to the ring as well. The traveller temperature reaches 400oC to 500oC and the danger of the traveller annealing and failing is very great.
All together restricts spindle speed, thereby production of ring frame.

Traveller Count:
  • It represents weight of ten equal type of travellers in grains.
  • OLD System: 10 travellers weigh 10 grains then traveller count = 1
  • ISO System: Weight of traveller in mgm OR Weight of similar 1000 travellers in gm.
  • 10 travellers weigh <10 grains then traveller is said to be the “Ought traveller” or ”Nought traveller”. Denoted by N/0; where N represents traveller count.
  • Higher the count heavier the traveller