Garment Sizing System Notes-3

1. Percentage returns in the catalogue retailing for casual apparels are 12-18%, More fitted fashion are 20-28% and for high fashion apparels are 35%.

2. The thumb rule to distribute an increament say 4 cm across the parts of the bodice: 62.5% to be done at the front.

3. Generic Size codes ( S, M, L, XL) are popular for sportswear and garments that fit loosely.

4. Mens clothing is generally communicated in terms of body measurement eg. 38.

5. In a study, it was found that the customer estimation of their body sizes were not accurate. People overestimated their stature and underestimated their hips. But was measured accurately.

6. Apparel sizing is often cited as the social benchmarking tool for women's bodies.

7. Bougourd explained that a size designation is most useful when tied to bodies' measurement.

8. Taylor and Shoben noted that the problem of grading sizing increase as the garment fit becomes closer to actual body shape conversely they decrease as the the garment category becomes looser.

9. Two inches girth grade was used as it was an easy division to a half inch measure when working on a folded front or back pattern piece.

10. In US, a grading of 1" done for smaller sizes, 1.5" for middle size and 2" for higher size. British and Australians work on flat 2" grading. 

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Garment Sizing System Notes-2

A. There can be three approaches towards development of sizing systems:

1. Indirect Approach: This approach measures dimensions such as weight and height and derive measurement based on these.

Shortcomings of indirect approach such as height relate to their variability. E.g. stature is composed of two components: trunk length and leg length. These two dimensions vary independent of each other they cannot be controlled by controlling their sums.

2. Direct:  This approach measures directly the dimensions to be measured such as chest girth.

3. Direct/Indirect:The third approach uses both the approaches.

As per ACK chan, in ready to wear garments, the exactness of fit is not too important at more than two dimensions of the body.

B. The design of the sizing system is a man-made convenience- based on factors of economy, fit and practicability.

C. It is a standard practice to use an odd number of sizes that will stand out for grading.

D. A size designation should have two things- length and girth.

E. As per ME Faust in "Apparel Designation and Sizing": Size designation should bear a definitive relationship to a garment's key measurements and convey adequate information to consumers of any target market.

F. The size interval ( Incremental difference) should incorporate the following:

a. A margin that is bigger than the measuring error.
b. Variation inherent in the manufacturing, allowing for stretch or shrinkage of the fabric during and after the process of manufacture.
c. Variations within the sizing of the body that the consumers are likely to accept.

As per ACK Khan regarding measuring error"... The intervals must be larger than the measuring error...", he further explains:

"...if a man of 88cm chest girth is being measured, it is possible for the measurements to appear as anywhere between 87 and 89 cm, due to different ways in which a person holds the tape measure during measurement taking. If a size interval of only 1 cm was chosen, this would mean a man may be assigned to different size depending on the way his body measurements had been taken. Also in a system, where small interval is used eg. 3cm, the argument in its favour is that it would lead to closer fitting garments. However acc to "Kunick" it is found that a garment that fits within the tolerance of +- 3 cm is quite acceptable, meaning that a size interval could be as wide as 6cm and still give a satisfactory fitting capacity. It can be further said that a garment can be of correct size but a bad fit, and in that case any variation in this size interval is unlikely to give any improvement. "

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Garment Sizing Systems Notes-1

1. As per S. Ashdown, devising a sizing system should seek to answer the following questions:

a. How many and which body dimensions must be used with reference to the garment in consideration. These dimensions are called control dimensions. These are also called primary dimensions. These are those that affect the goodness of fit in a garment and are the dimensions that are measured on a customer to match them with the right sized garment.

b.  What portion of the range to be covered. This is called size range. 

c. How the grouping of these sizing should be done. This is called Size, Inter size interval or size steps. 

d. How many sizes must be produced and how many garments must be produced of each size. This is called size roll. 

e. Which other dimensions are important for garment constructions. These are called secondary dimensions. These are dimensions are dimensions which are used together with primary dimensions to define the body size of one person as a whole.

f. How the garment must be labelled. The aim is of unmistakable identification, this is called size designation. As per the author "...often it is not clear whether the size codes printed on the label refer to the garment or body measurements or to which area of the garments and body in particular.

2. It is also important to know what portion of the population is provided for by the sizing system. This is called accommodation rate. This is between 65% to 85%

3. Choice of Intersize Interval can be understood with the following observations by Koblyakova:

a. One needs to find out the interval of indifference. It is defined as that interval between sizes along some dimensions that doesn't make a difference to the wearer.

b. The interval of indifference is considered to be twice the average tolerance level, which is defined as the largest increment along a dimension that will not be recognized by the wearer. The value of the level of indifference depends upon various factors:

i. Body dimensions with larger absolute values ( such as stature or hip girth) will have larger intervals of indifference than dimensions with smaller absolute values ( such as arm length or neck girth)

ii. Another factor affecting the interval of indifference is the property of the fabric used for garment. Greater flexibility and stretch of the fabric would increase the level of tolerance, therefore increasing the interval of indifference and hence the secondary intersize interval.

iii. As per Koblyakova, the following size step guidelines can be used for topwear:

6cm for Outerwear
10 cm for mens shirt
12 cm for knitwear.

iv. As per ISO, the following size step guidelines can be used- for topwear:

Womens, all size steps without knits- 8cm
Knits- 6cm

4. Secondary Dimensions describe a body in the details necessary to construct a garment that fits a body. 

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Womenswear Measurements - Some Thumb Rules

1. Relationship between Across Front, Across Back and Across Shoulder

Here Across front is taken at mid armhole. The three measurement taken together are used to draft and gauge armhole shape.

For woven fabric Across front should be 1.5" less than Across shoulder and Across Back should be 0.5 inches less than the Across shoulder.

2. Back and Front Armhole

The Back Armhole should be 1/2 to 5 1/8" bigger than the front Arm Hole

3. Front and Back Neck Width

Back Neck width is 1/2 inches bigger than the front neck width.

Read the full article here and here

How to Make Patialas and Churidars

Here are two amazing videos on the techniques of Making Patiala and Churidar

Fabric Losses during Spreading

The percentages of various costs that add up to the garment cost are as follows:

1.Raw Material cost: 50%

2.Direct labour Cost: 20%

3.Indirect Labour charges and factory overheads: 30%

The raw material cost ranges from 40% for hosiery to 60% for lingerie. The cost of fabrics is 80% of the cost of raw material. 

The fabrics can be broadly divided into the following three categories:

1. Tubular Knitted Fabric

2. Narrow open width fabric: The fabric width can accommodate two body pieces. Maximum market efficiency can be achieved if the number of smaller pattern pieces in the garment are relatively more. 

3. Wide open width fabric: This type of fabric is having a width of 1.5 meters and three body pieces can be placed in the width of the fabric. 

Fabric Losses

During the cutting process two types of fabric losses occur:

1. Marking Loss

2. Spreading Loss

Marking Loss arises due to the gap and the nonuseable areas at places between the pattern pieces of a marker. Marker efficiency indicates the amount of marking loss. 

Spreading loss is the fabric loss outside the marker. The various fabrics outside the marker are classified into different groups:

1. End of Ply Loss

2. End of Piece Losses

3. Edge Losses

4. Splicing Losses 

5. Remnant Losses

6. Ticket length Losses

1. End of Ply loss: The flexibility, limpness, extensibility alongwith the limitation of the spreading machinery necessitates an allowance of some fabric at the end of each ply. These losses may be upto 2 cm at each end or 4 cm per ply.

The end of ply loss is 1-2% of the total fabric usage. 

2.  End of Piece(Thaan) Losses: In textile industry, fabrics are produced and processed in different batches. This makes the fabric ends unsitable for use due to marks or distortions created.  

The end of piece varies from 0.5-1% of the total fabric usage. 

The loss is minimized if the average length of pieces that are purchased is increased. 

3. Edge Losses:  In normal practice during marker planning, the width of the marker is kept a few centimeters less than the edge-to-edge width of the fabric. The marker is made according to the usable width of the fabric. The usable fabric width depends upon the quality of the selvedge, the consistency of fabric width, and also on the precision of edge control during spreading. Let the fabric edge-to-edge width is 100 cm, and the marker width is 3 cm less than the fabric width. The edge loss is 3%. If the fabric edge-to-edge width is 150 cm, the loss is 2%.

Thus wider width has other benefits besides improved marker efficiency. 

4. Splicing Losses: Splicing is the process of overlapping cut ends ( the end of one length of the fabric and the beginning of the other) of two separate pieces of the fabrics so that the spreading is continuous.  Splicing is necessary as one roll of fabric is finished and the next taken into use. 

Also during spreading there may be some objectionable fabric faults, which make the product unsalable or substandard. These fausts are removed by cutting the lay at the fault point and incorporating splicing position into marker plans. 

During splicing the splicing line should be so selected that none of the pattern pieces contains the fault is incomplete. 

The position of the splice lines also dependent on the quality of the fabric being spread. If cutting out faulty material at the lay is a regular requirement, it is vital that the markers are provided with clearly defined splice lines. 

The splicing losses may vary up to the 5% of the total fabric usage. 

5. Remnant Losses: Remnant lengths are produced whenever companies separate different shades of fabric pieces and lay up only complete plies. 

Remnants are also generated when short lengths of material are left over after the completion of the lay, and are returned to the stores. 

All remnants are put to one side and cut separately. 

6. Length Losses ( L Losses): Woven fabrics and some knitted fabrics are sold by length.  Each fabrics piece is measured by the fabric supplier and a ticket is attached to each piece indicating the length for which the customer is invoiced. In many cases the gross length and the net length are marked in the ticket. This loss can be reduced by inspecting the length of the incoming fabric and reporting the fabric supplier in case of yardage short. 

Source

Ergonomics in Apparel Industry

Workers involved in sewing activities such as manufacturing garments, are at a risk of developing musculoskeletal disorders. Therefore it is imperative that the design of sewing station, stitching, finework,scissor work and material handling should be ergonomically appropriate. This site talks about ergonomical solutions for the same. A lot of sketches and diagrams are given for easier understanding. Some very quick rules of thumb can be derived from the sketches:

1. Chair Height is correct when the work surface is at elbow height and the sole of the foot should rest on the floor.

2. Schedule frequent and short breaks to stretch and change position.

3. Height and Tilt adjustable tables help employees access their work without using awkward postures.

4. Edges of work surfaces should be padded or rounded, so that the workers can rest their arms against them.

5. Use of Adjustable task lighting and magnifying glasses at workstation can take care of fine work inspection.

6. Shorter width table should be used for scissorwork so that the workers dont have to bend and reach so far.

7. Lifting of weight should be done at waist level.


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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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8 Things to Remember While Spreading Fabric

Things to remember While Spreading

1.      Mark the Splice Zone on the Spreading Table

Spreading is an operation in which bolts of fabrics are unrolled on a table in such a way in order to produce a multi-layer stack, so as to facilitate cutting.

Fabrics usually contain many defects. The defects in pieces which are cut into patterns are highly undesirable. To avoid this, the spreading operator must identify and cut out defects as the material is being spread on the table. However, if the material is cut in the mid of the pattern, it will lead to more material wastage.

To avoid this, zones are defined called splice zones, where cuts can be made by the spreading operator. Also it is also required to decide about the overlap of the next section of cloth. Thus there are two lines in a splice zone: One line shows how far the previous piece of cloth must extend, and one line shows where the next piece of the cloth must begin, ie how much overlap is needed.

Thus when a flaw is encountered, the spreader is stopped, the operator moves back to the nearest splice point, cuts the flaw out and moves the spreader back to overlap the cut line with the required overlap.

Apart from cutting out defects, splices are also used to achieve proper shade matching when starting a new roll of cloth.

Thus the splicing points are marked by means of a chalk or paint.

2.      Use Paper for the first ply in case the table surface is rough or when fine fabrics are being spread

3.      Identify the defects noticed in the fabric by means of stickers

4.      Use lubricated paper for separating layers

a.       To prevent scorching in the natural fibers ( coarse fabrics)

b.      To prevent fusing in the synthetic fabrics

5.      Ensure that decided number of ply count and height of the spread is achieved.

6.      How to spread

a.       Mount the bolt on the machine

b.      Pull the fabric to far end position

c.       Position the fabric at the far end ( with our without weight or pins)

d.      Align the ply ( width on one side)

e.       Cut the ply after each lay

f.       Repeat this process from b-e until the entire bolt is spread.

g.      Check ply count

h.      Repeat a and then b to g till the decided number of ply are spread

i.        Mark the remnants of the bolts with length in meters and bolt number and stack separately at the given place.

7.      How to Splice

a.       When the ends of the patterns in a marker are joined on both sides by straight line then use the single line splicing. Make sure that overlapping at this point should be about 2”

b.      When the ends of the patterns in a marker interlock at a common vertical line across the width then use two line marking with a diagonal indicating common area that must be overlapped when patterns in a marker interlock at a common vertical line across the width.

8.      When the required height of lay is achieved, place the marker on the spread and secure it by means of brass pins on each pattern section.

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Additional Reading: Indian Textile Journal

Seam Strength Vs. Seam Slippage

Difference Between Seam Strength and Seam Slippage

Both the parameters measure the performance of seam. Seam strength referes to the strength when seam finally ruptures or when the fabric breaks.

However before rupturing there is an unacceptable opening in the seam which makes the seam 'failed' commercially even when there is no visible rupture. Seam slippage measures that.

Seam strength depends upon stitch type, thread strength, stitches per inch, thread tension, seam type and seam efficiency of the material.

Seam slippage depends upon the stitch rate, the weave structure of the fabric and the width of the seam allowance.  

There is another term called 'yarn slippage' which measures the shifting of warp yarn over weft yarn to render the garment unusuable. 

Yarn slippage depends upon a low number of warp or filling yarn, two shallow seam allowance, too tight a fit and improper seam construction.  

Find Pictures of Seam Quality Defects here.

12 things to Ensure While Marking Master in Garment Manufacturing

12 things to Ensure While Marking Master in Garment Manufacturing

1. Do it only on the selected marking material

2. Ensure Number of patterns necessary for each style to make a complete garment.

3. Ensure facing of the patterns ( faceup, down, lateral, longitudinal) to facilitate cutting in design direction. Provide identification mark with respect to spread type eg. "FU" for face up, "FD" for face down and "FF" for face to face.

4. Determine the grain marking on pattern such as straight, cross and mixed.

5. Note the warp (straight), weft (cross) and bias grain dimension of each pattern.

6. Ensure that the grain alignment on the marker is within the graining tolerances as specified on the pattern.

7. Mark the pattern wholse widths sum up to equal the fabric width shall be marked in parallel formation across the width.

8. Achive maximum interlock efficiency of patterns with tapered width by inverting the alternate pattern depending on the fabric design.

9. Avoid crowding of interlocking angles and curves which restrict the cutters ability to cut the pattern section with precision.

10. Provide sufficient knife clearance for manipulation of cutting machine at interlocking curves and angles.

11. Draw lines with precision ( line value to facilitate cutting)

12. Mark each pattern section with its size, style and pattern title/number.

16 Things to ensure while Making Industrial Apparel Patterns

The following is a list of 16 things to ensure while making an industrial apparel pattern manually:

1. All the features of the style
   
2. Pattern count ( Number of pattern sections) according to the style 
   
3. Seam allowance based on style
   
4. Type of fixtures required on sewing machine in the manufacturing
   
5. Final drafting measurements based on the shrinkage value ( both warp and weft way) for garmens which are subject to further treatment such as washing or dyeing.
   
6. Grading the pattern based on the size specification.
   
7. Marking the grain lines by an arrow head.
   
8. Provide guide notcher for precision assembly, punch holes for positioning of components and darts.  
   
9. Use of white hard board paper for drafting.
   
10. Use of black color for drawing the original draft line.
    
11. Identify the pattern by its style number, customer's name, date of preparation and mention of its status as "sample"
    
12. On preparation of the sample garment, place all the pattern sections in a paper bag mentioning pattern count, style number, customer's name 
    
13. On receipt of customer's feed back on sample garment effect the changes, if any, by manipulating the draft with Blue color and endorse with signature and date.
    
14. On approval from the production manager, change the status of patterns from "sample" to "production"
    
15. On finalisation of drafting , prepare "ready patterns" on two tone paper for small components meant for cutting section, sewing section and for monitoring purpose.
    
16. In order to prevent curling and chipping of the edges of the pattern section, protect the edges by metal foils.  

Tags: Pattern+making, drafting, garment+manufacturing

Major and Minor Defects in Garment Production-3

Small Parts
Major Defects
1. Rib Knit set crooked-off, grain holes or runs in knit.
2. Misshaped collars and cuffs
3. Misshaped Tabs
Zippers
Major Defects
1. Zipper more than 3/8" from bottom.
2. Poorly set zipper causing closure problems.
3.Twisting of the zipper caused by the top stitching of the zipper front.
4. Poorly set zipper causing waviness in the front.
Minor Defects
1. Twisting of the zipper front caused by the top stitching of the zipper front.
2. Setting front ( or facing ) too close to the teeth so that the slider cannot properly function.
Button/buttonholes
Major Defects
1. Button and button holes not set in proper positions or out of alignment.
2. Uncut buttonholes/ missing button/ snap fasteners/ buckles/ zippers etc.
3. Not set in proper position
4. Defective or rusted hardware
5. Hardware not according to the specification in size, color, shape.
6. Snap coming off tacks ( Bartacks)
7. Omitted or misplaced or rivet not servicing its intended purpose/improper length.
Minor Defects
1. Too few stitches in the buttonhole.
2. Buttonhole too large or too small for the button.
3. Button not securely sewn.

Major and Minor Defects in Garment Production-2

Assembly Defect

Major Defects

1. Finished Components not correct to size or shape or not symmetical

2. Finished garment not to size.

3. Measurements not within tolerance.

4. Parts, components, closures or features omitted ( i.e. Belt loop, snap or button)

5. Components or features wrongly positioned or misaligned

6. Interlining incorrectly positioned twisted, too full, too tight, cockling

7. Garment parts, cockling, pleated, twisted, showing bubbles and fullness.

8. Garment parts shaded or shading in fabric.

Minor Defects:

1. Loose Thread not removed

Major and Minor Defects in Garment Production-1

Some very good definitions of Major, Minor and Critical Defects can be found Here.

Major, Minor and critical Defects are the part of classification given to the flaws while inspecting the fabrics or garments.The classification depends upon the severity of the defect and forms a basis of acceptance or rejection of the lot.

Consideration in classifiying the defects as major or minor is taken on the basis of the affect on saleability of the garment, location of the defect and conspicuousness of the defect.

In this document , the location of the defect( the zone) is shown in various garments which make a defect serious or insignificant. There is also a comprihensive list of the critical defects.
An analysis of Fabric defects according to their severity as major or minor can be found in this document.

This document is in the form of a contract but it deals brilliantly with all the quality issues including the defects.

The Following is an indicative list that can be followed to ascertain if a defect is a minor or a major defect in a garment:

Seam and Stitching

Major Defects:

1. Stitch Requirements
a. Inside 8-10 SPI
b. topstitch 8.9 SPI
c. Other requirement as specified

2. Seam grain
3. Thread breaks
4. Feed damage
5. Excessive amount on skip stitches ( 2 or more)
6. Pleat in seam (other than required by style)
7. Poorly repaired seams
8. Broken stitches two or more if conspicuous.
9. Conspicuous needle damage hole.
10. Open seam raw edges or frayed materials
11. Uneven stitch density, staggered stitch
12. Too many stitches giving rise to jumping and rupture of fabrics and few to grinning and weak seams
13. Wrong stitch density
14. Run off stitch.
15. Omitted sewing i.e. top stitch, button hole, snap, velcro etc.
16. Serious, uneven edge of seam ie bottom of waistband, right to left seam matching, pocket mouth etc.
17. Double stitching and poorly repairs affecting the appearance and service.
18. Improperly formed stitch or loose tension of stitches causing loops on surface easily pulled out.
19. Stitch tension which breaks under normal stress.
20. Wrong colour match thread
21. Napped fabric-cut or sewing in the wrong direction or mixed in the garment causing shading.
22. Wrong seam type or stitch type used
23. Blind stitching showing on the face side.
24. Reverse garment parts.
25. Extraneous part caught in seam.
26. Mismatched seam.
27. Mismatched checks or stripes
28. Any twisted, loosen, tighten, puckered or pleated or overlapped seam.
29. Irregular or incorrect shape of sewing line "run-offs"
30. Incorrect or uneven width of inlay i.e. seams burst open, raw edges show slippage of weave threads.

Sewing Problems

Sewing Problems

1. Problems of stitch formation

It gives rise to poor seam appearance and performance

These are

- Slipped stitches
- Staggered stitching
- Unbalanced stitches
- Variable stitch density
- Puckering
- Needle, bobbin or loops thread breakage

a. Slipped Stitches

Arise from the hook or loopes in the machines not picking up the loop in the needle thread.

b. Staggered Stitches

Can be caused by yarns in the fabric deflecting the needle away from a straight line of stitching, giving a poor appearance.

c. Unbalanced stitches

It can reduce the potential of stretch in a seam in a knitted fabric and may lead to seam cracking.

d. Variable stitch density

It arises from insufficient foot pressure in a drop feed system, causing uneven feeding of the fabric through the machine.

PROBLEMS OF PUCKER

Pucker is a wrinkled appearance along a seam in an otherwise smooth fabric. It generally appears as if there is too much fabric and not enough thread in the seam.

Causes of Pucker

a. Seam pucker due to differential fabric stretch

Remember that the upper fabric would tend to move forward by an amount always less than the movement of lower one. This is due to the fact that the lower layer is positively gripped by the feed dog and upper layer is driven by the friction by the lower layer.

b. Differential pucker caused by fabric dimensional instability

The essential feature causing differential pucker is the relative change in dimensions of upper and lower fabric after the seam has been made.

Differential pucker due to dimensional instability may be suspected when the two fabrics being joined are markedly different or when one shows noticeably more pucker than the other.

c. Seam pucker due to extension in the sewing threads.

All sewing threads have some extensiblity and they are extended by the action of the tension devices and pass into seam in an extended state. When removed from the machine they will tend to contract.

When thread extension is proved to be the cause of puckered seam, consideration must be given to the type of thread being used and to the tensiton settings on individual machines.

d. Seam pucker due to sewing thread shrinkage

Cotton sewing threads increase in diameter and shrink in length when wet and these distortions may cause pucker in sensitive fabrics. Synthetic sewing threads have negligible wet shrinkage and should always be used for such fabrics.

e. Seam pucker due to structural jamming

The presence of the seam itself may introduce a distortion. It is in no way dependent on the action of the sewing machine, but it invariably appears as soon as the seam is formed.

As soon as a woven fabric has been constructed so as to be close to the practical weaving limit, that is very less space left between the yarsn either warp or weft ways, it may be extremely difficult to force in any more threads in either direction.

The term 'structural jamming' is given to this type of pucker because it results directly from the act of jamming extra threads into a structure which is already too closely set to accommodate them.

Seam pucker due to mismatched patterns

This is due to the discrepency between the lengths of the stitching lines on the pattern pieces that go together in the seam. Thus there is a difference in the lengths of the cut parts which the machinist is sewing together.

Problems of damage to the fabric along the stitch line

a) Mechanical damage

1. Needles can strike and break fabric yarns and burst the loops in knitted fabrics. For this appropriate set and ball point needles are necessary.

2. Needles should always be as small as possible.

3. Sometimes the combination of the machine speed and nature of the fabric prevents the yarns from moving out of the way of the needle sufficiently fast to avoid damage .To solve the problems either reduce the speed - which means lesser production or ensure that the fabric is adequately lubricated. It calls for having resin finish on the fabric.

- All sample lengths of the fabric should be tested for sewability and the necessary finishes should be specified before the bulk fabric is ordered and bulk fabric should be tested before production to ensure that finishing treatment has been effective.

b) Needle Heating Damage


Needles heating occurs as a result of friction between the needle and the fabric being sewn.

In high speed sewing of dense material, temperatures as high as 300 deg or even 350 deg can be reached.

At this temperature it is possible that the needle may suffer damage and lose its hardness.

Natural fibres in a fabric or thread can withstand these temperatures for a short time.

With synthetic fibres, the position is more critical since the fibres melt at around 100 deg C, polyamide and polyester soften at about 230 deg C and polyacrylics will only withstand temperatures upto 280 deg C.

Overheated needes can
- Soften the synthetic fibres
- Weaken them
- Produce rough seam with
- harsh stitch holes

Melted fibres stick to the surface of the needes
- Increase its friction
- cog the eye and the groove
- No sew
- Skipped stitches

Reduction of Friction
- Reduce the sewing speed
- Changing the shape or surface of the neede
- long seams will ensure more heat build up in the needle
- Jet of compressed air.
- User spun or corespun yarns.

Sewing-9

Thread Sizing

1. Metric Ticket Number system

eg if Nm 60/1 means 60m of it would weigh 1 gm.

of 120/2 means 120 m of it would weigh2 gms. In this case it would have a resultant count of 60 ( i.e. 60 gms) would weigh 1 m.

The metric ticket number of this thread based on a three fold equivalent is then three times that i.e.

Nm 80/2= Ticket Number 120
Nm 30/3 = Ticket Number 30 and so on..

2. Cotton Sewing threads are sized on the cotton ticket number system

eg. 3/60 Ne --> equivalent cT= 20--> Three fold equivalent = 60 ( Ticket Number)

3. Denier system--> Weight in gms of 9000 m of length

Thread Packages

1. Spool

a. Used for domestic sewing
b. Not suitable for delivering thread to high speed industrial machines.

2. Cops

a. Small cylinderical flangeless tubes onto which thread is cross bound for stability.
b. Lack of flanges facilitates regular offwinding from the top on sewing machines.
c. Their small diameter makes them less suited for the faster thread offtake of machines.

3. Cones

a. They contain 5000 m cross wound for stability and good offwinding performance.
b. They give troublefree thread delivery.
c. Ideal in situations where thread consumption is high.

4. Vicone- Contain any spillage

5. Large Package

a. Can hold in excess of 20000 m of spun or corespun thread

6. Container

cocoons: They are self supporting ie. centerless, thread packages.

Sewing-8

Thread Finish


The final aspect of thread construction to be studied is that of surface finish.

The most important finish is lubrication.

The requirement of a lubricating finish applied to a sewing thread is that it should produce a regular level of friction, and that for synthetic threads in particular, it should provide protection from needle heat.

Without a controlled amount of lubrication applied to threads, unacceptable damage would be inflicted on them during the sewing process which would result in thread breaks during sewing and seam breakdown in wear.

A lubricant


- Must not clog the needle eye
- should not stain
- Must allow thread to unwind evenly from the package
- Must reduce friction with m/c surfaces but without creating too much slippage
- Must not react adversly to high temperature
- Must be inexpensive
- Easy to apply to the thread during manufacturing.

Other finishes


- Mildew or rot resistant finish
- Water resistant finish
- Soil Release
- Flammability finish

Sewing-7

Sewing Threads

Threads can be

Spun


Threads made from spun yarn have good sewing performance, good dimensional stability and good stitch locking properties in the seam due to their fibrous surface.

Monofilament


One filament of large size. It is harsh on machine and rather inflexible because the cross sectional shape never varies as it would with multifilaments.

Its cut ends are harsh on the wearer. It has virtually no seam grip and stitches tend to unravel easily.

Its good advantage is a translucency which reduces the need for shade matching.

Multifilament Form


Their fineness enables larger thread packages to be used, thus saving operator time changing them.

Corespun


In this a continuous multifilament core is wrapped around a sheath of spun fiber, two or three of these yarns are then plied together.

The majority of these corespun threads consist of a polyester core and a cotton cover.

Sewing-6

Sewing Threads

Selection of sewing threads depends upon the following factors:

1. Performance properties during sewing
2. Performance in the completed garment under conditions of wear and cleaning

Appearance and perfomance of the threads depends upon:

1. Fiber Type
2. Construction
3. Finish

1. Fiber Type

a. Linen- Useful in making strong, rather stiff threads for heavy sweing and also for button sewing.

b. Slk - Advantage- Good appearance and performance, Disadvantage- High Cost

c. Cotton - Good Sewing Performance, Disadvantages- Strength and abrasion resistance are inferior to synthetic threads of equal thickness.
It is more stable at higher, dry temperature than synthetics- less affected by hot needles during sewing.

d. Viscose- 1. Do not have the strength or durability of synthetic fibres. 2. Low tenacity and low strength when wet. 3. High lustre- can be used for embroidery.

Nylon/ Polyester Threads
1. Not affected by rot, mildew or bectaria
2. High Tenacity
3. High resistance to abrasion
4. Good resistance to Chemicals

2. Construction

When the fibres occur in short lengths, they must be twisted together, initially into a single yarn, and then that twist must be balanced by applying a reverse twist, as two or three such yarns are combined to form the thread construction.

- Twist in singles yarn consolidates the strenth and flexibility provided by the fibres themselves.

- Without the reverse twist, known as finishing twist, a conventional thread cannot be controlled during sewing. The individual plies would separate during their repeated passages through the needles and over the sewing machine control surface.

- Remember that the frictional forces acting on a thread during its passage through a sewing machine also tend to insert some twist, predominantly in one direction.