Sunday 29 November 2009

Influence of Fiber Fineness and Maturity in spinning Process




Influence of Fiber Fineness and Maturity on spinning Process



Fiber Fineness

Fiber fineness determine how many fibers are present in the cross section of a yarn of given thickness. Additional fibers in the cross section not only provide additional strength but also a better distribution in the yarn. Minimum 30 fibers are needed, usually over 100 fibers are required. Fiber fineness influences spinning limit, drape of the fabric, yarn strength, luster, yarn evenness, handle, yarn fullness and productivity. Productivity is influenced by reduced end breakage rate.

In a conventional spinning process, fine fibers accumulate to the core and coarse fibers in the periphery.

Fiber fineness is measured in dtex which is equal to ratio of mass in dgrams and length in km. Decitex is equal to the product of Micronaire value of the cotton and 0.394.

Cotton fibers are generally classified as very fine if they have a micronaire value upto 3.1; fine if they have value between 3.1 to 3.9; medium if they have it between 4.0 to 4.9; slightly coarse between values of 5 to 5.9 and coarse if they have a micronaire value above 6.


Fiber Maturity

Cotton fiber consists of cell wall and lumen. The maturity index depends upon the thickness of the cell wall. The fibers are considered ripe if they have maturity index between 50-80 percent, unripe if they have MI between 30 to 45% and dead when they have it less than 25%.

Unripe fibers have neither adequate strength nor adequate longitudinal thickness. They lead to loss of yarn strength, neppiness, high proportion of short fibers, varying dyeability, processing difficulties mainly at the card.



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Wednesday 25 November 2009

Fiber Identification - Burning Test- Man-made Fibers





All viscose including High Wet Modulus scorch and ignite quickly when brought near the flame. Like cotton they burn quickly with yellow flame when in the flame. When removed from the flame they continue to burn. There is no afterglow unlike cotton. The smell is that of burning paper. They leave a light gray and feathery ash.

Acetate Rayon  ( And Triacetate Rayon)

When brought near the flame, it fuses away from flame turning black. When in the flame, it flames quickly. The fabric puckers, sputters and melts. It drips like burning tar. When removed from the flame, it continues to burn and melt. It smells like vinegar. It leaves a brittle hard, irregular black ash which is difficult to crush.


3D diagram showing the variants nylon 6 and ny...Image via Wikipedia








Nylon fuses and shrinks away from the flame when brought near the flame. In flame, it burns slowly without melting. When removed from flame the flame diminishes and tends to die out. It has somewhat pungent odor. It leaves a hard, round, tough and gray bead.


When brought near the flame, it shrinks away from the flame. When in the flames it puckers and chars. When removed from flame, it extinguishes by itself. It has no smell and it leaves a hard black bead.





Scanning electron microscope image of a bend i...Image via Wikipedia

Polyester fuses and shrinks away from flame. When in flame, it burns slowly with melting. When removed from the flame, it burns with difficulty. It has slightly sweetish smell. It leaves a hard round brittle, black bead.


Orlon, Acrilan and Creslan and Zefran fuse and melt away from Flame when brought near the flame. When in flame Orlon flames rapidly. The fiber puckers, sputters and melts. Acrilan flames rapidly and melts. Creslan flames and melts and Zefran sputters slightly and flames. When removed flame all of acrylics continue to burn and melt. Orlon has a slightly burning meat-like smell. Acrilan has a buring steak smell. Creslan has sharp sweet smell and Zefran has a turmeric like smell. Orlon, Acrilan and Cresla have hard, brittle and irregular black bead. Zefran has irregular black ash that can be crushed easily.

Modacrylics

Verel and SEF fuse and shrink away from the flame when approached near a flame. When in flame, Verel burns very slowly with melting. SEF shrinks, melts and smolders. When removed from flames, all modacrylics are self extinguishing. Verel has a gunpower smell whereas SEF has a sharp sweet smell. Verel leaves a hard and irregular black bead whereas SEF leaves a hard and irregular black bead.


Fuses but doesn’t shrinks away from the flame when approached near the flame. When in flame, it burns with melting. It has an acrid smell. It leaves a soft, fluffy black bead.

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Sunday 22 November 2009

Identification of Natural Fibers by Burning Test



Identification of Natural Fibers by Burning Test


Cotton

When cotton is brought near the flame it scorches and ignites readily. In the flame it burns quickly with yellow flame. Upon removing from flame it continues to burn rapidly and shows afterglow. It emits a smell of burning paper. The Ash is light, feathery and grayish. If the ash is black it denotes mercerized cotton.

Linen

Linen like cotton when brought near the flame scorches and ignites easily. In the flame it burns slower than cotton with yellow flame. Upon removing from flame it continues to burn with a smell of burning paper. The ash residue is feathery and gray.

Wool

Wool when brought near the flame smolders. In flame it burns with small and slow flickering flame. Also in flame it sizzles and curls. When removed from flame it ceases to burn. The Odor is like that of burning feather or hair. It gives crisp, dark and irregular shaped ash that can be crushed easily.

Pure Silk

Pure silk smolders when brought near the flame. In the flame it burns slowly with sputtering. When removed away from flame it continues to burn but with difficulty and ultimately extinguishes. The smell that is emitted is like that of burning feathers or hair but it is less pronounced than wool. It gives out a round, crisp, shiny black beads that can be crushed easily.


Weighted Silk

Weighted Silk smolders when brought near the flame. In the flame it burns with a glow. When removed from flame the burned part becomes briefly incandescent then it slowly chars. The smell is like that of pure silk i.e. burning feather or hair. The ash brings a screen like skeleton of original sample.

The following guide is very handy in identifying the fibers by burning test:





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Sunday 15 November 2009

13 things to ensure while cutting



Cutting Room Procedures ( Image Source)




 1. Knife guard should be adjusted according to the height of the lay.

2. The correct position of the blade, its sharpness and the reciprocating speed of the machine should be ensued.

3. Cut the lay of fabric by propelling the cutting machine on the marking line with accuracy.

4. Projections for each pattern section should be provided to facilitate the sorter in numbering the cut sections.

5. Provide notches at appropriate places with required depth.

6. Mark the position of pockets, embroidery, logo etc. by drilling small hole through the lay with correct drill bit .

7. Frayed, serrated, fused or scorched edges, ripped or pulled yarns, overcut and undercut should be avoided while cutting.

8. On Bend knife machine, use ready patterns aided by appropriate fixtures for carrying out precision cutting.

9. Sections which need to be cut individually (e.g. checks to be aligned in the front panel) are to be respread and folded by aligning the checks/stripes.

10. Use appropriate fixtures to ensure the matching of the folded sections.

11. Discard the cut scrap into the caster bins positioned near the table.

12. Tie the cut lay along the cut sections of the master marker in a bundle.

13. Erase the splicing and the end marks after the spread is cut and bundled.

Safety Instructions in Handling Cutting

a. Areas near cutting tables should be clearly marked, and their access restricted should be restricted by barriers.

b. On motorised and automatic cutting tables the warning signals should be fitted to indicate when blade is in motion.

c. The machine ideally should be fitted with automatic adjustable guards to fully cover the exposed part of the cutting blade.

f. The five finger chain blades should be available to all the operator working on knife and should be worn on all times during cutting work.

g. There should be a regular check on the condition of the light, guard, and table fittings.

h. Only fully trained operatives should be allowed to work on knives.

i. The operators' standards should be checked against the published operating practice on a regular basis and should be corrected wherever a deviation is found.

j. There should be an effective cleaning system in operation that prevents build up of fluff, fly and off cuts, thus reducing fire, health & trip hazards?

A complete of list of safety measures can be found here


For those who want to go in for technical details they can click here for round knife and here for straight knife .

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Sunday 8 November 2009

The Sari- Some Facts, Methods, Techniques and Measurements



The Sari has not lost its appeal in modern India. Despite the growth of Women Western and other modern outfits, the charm of Sari remains. 

A users manual on How to Wear a Sari can be found here or here . A visual guide to various styles is presented here.

An amazing classification of  Different Saris of India can be found on the site of Indiangarment.com. You can find a complete manual of Indian Saris here.

A very nice manual on the measurement for various Indian garments such as Churidars, Parallels, Sharara, Lehnga Chunni or Ghahgra Choli and blouses is given on the same site.

And of course, an interesting concept of Automatic Sari is also given.

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