Sunday, 8 March 2009
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
Terry Towel Manufacturing Process
In addition to what I have mentioned earlier, Terry Towelling is excellently described in this blog.
Replete with pictures, this post replies succintly the various process steps in manufacturing terry towel.
Saturday, 7 March 2009
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.
Thursday, 5 March 2009
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.
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