Thursday, August 13, 2015
Sweaters are very popular among all classes of people. Adults, teens and children wear sweaters. These become very popular during winter season because these keep the body warm. These are also popular because of some other reasons such as these are not tight fitting, easy to wear, colorful and fashionable.
Sweater is a piece of knitted or crocheted garment specially made from wool. Sometimes cotton or synthetic fibres are used. It covers the upper part of the body. To clean sweaters, washing or dry cleaning is done.
There are two derivatives of sweaters. One is cardigan and the other is pullover or vest. A cardigan is a sweater that opens in the front side of the body and can be closed with ties, buttons or clasps. A pullover is the most common type of sweater and covers around the torso and arms. Lastly, the vest has no arms and is typically worn over a blouse, long sleeve shirt or other knit shirt.
Now, I’ll describe the process flowchart of Sweater manufacturing in brief with an image–
Monday, October 27, 2014
All about Repair, Maintenance, Setting and Replacement of Different Parts of Straight Knife Cutting Machine
Introduction: Machines condition will be deteriorated if it is exposed to the environment and subject to use. If these process remain unchecked and unchanged it will cause unserviceable and standstill of the machine. Industry therefore has no other way but to attend, to repair, to maintain, to set and to recondition them so as to prolong their life to the extent it is economically and physically possible to do so. So according to engineering aspect respects repair, maintenance, setting and replacement of different parts of the machines are badly needed and so on.
a. Flat screw driver
b. Star screw driver
e. Lubricating oil
Repair: Repair work is carried out when a component requires slight modification. To carry out such job the machine needs to be switched off first. The component under repairing, the part is fixed to its designed place and hence its correction is measured by running the machine. In a straight knife cutting machine motor, knife, knife guard, wheel, base plate wheel controller, can undergo repair job.
Maintenance: Maintenance can be of different types. But following types are important in this aspect.
A. Routine maintenance: Lubrication and regular inspection are the constituents of routine maintenance. Lubrication ensures long life and safe working of all the equipment. Inspection tries to detect fault in equipment so that repairs and replacement may be undertake at right time.
B. Scheduled maintenance: This type of maintenance provides for inspection, overhaul lubrication and servicing of the machine at predetermined dates. Overhauling of machine, cleaning of all components is normally done in this manner. It involves opening of the machine into its smallest components and carry out lubrication.
Setting: The setting of the machine is of immense importance. Following setting points need to be ensured before running the machine.
a. Knife: In straight knife cutting machine, the knife is straight and it has reciprocating motor. The height of blade ranges from 1.-33 cm and the stroke of blade ranges from 2.4 - 4.5 cm. The setting of knife is very important. For smooth cutting, the knife maintenance is very necessary.
b. Sharp edge of straight knife: The sharp edge knife may have various shapes for various extent of cutting. Such as, to cut soft and fine lay of fabric, straight edge is used to cut canvas fabric, sew edge is used to cut coarse and heavy cotton fabric, serrated edge is used. So, the sharp edge of knife should be selected according to requirements.
c. Motor: Motor rpm expresses the speed of the machine. In straight knife cutting machine, two types of force are required i.e. for the reciprocating motion of straight knife and for the movement of knife inside the lay of fabric. The rpm is controlled by regulator of motor and the movement of knife inside the lay of fabric.
d. Fabric height controller: Fabric height can be controlled by controlling the height of blade. Fabric height should be controlled depending on types of fabric, cutting efficiency, requirement etc.
Replacement: The replacement is revealed when the retention on equipment is no more remains an economical proportion. A replacement is affected when the equipment is subjected to complete breakage which cannot be used even after repair or the component has become so obsolete that affects production or it has crossed its expire date. Replacement can be affected to any components of the machine at any time. In straight knife cutting machine, main component knife undergo frequent replacement. The griding wheel, base plate wheel need not to replace very frequently, but they need to be replaced for proper function of machine.
Precaution: Following precaution must be taken when repair, setting, maintenance or replacement is carried out in the straight knife cutting machine.
1. All repair and maintenance work must be carried out by switching off the machine.
2. Careful handling of all the components is necessary.
3. Right tools should be used at right place and right time.
4. The components should not be too tight or too loose.
5. Skilled personnel should be involved for specialized job.
Conclusion: Every industry has to carry out such this maintenance procedure in each reputed industry maintains a maintenance department. They follow these points during their procedure.
Credit goes to_
Md. Arafat Islam
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Thursday, October 23, 2014
Introduction, Features, Adjustment point and Main m/c parts, Function, Maintenance, Setting, Replacement, precaution of lock stitch/plain stitch machine
Introduction: The machine which produces stitch by interlacing of threads is called lock stitch machine. This machine produces durables and is very popular in garment industry.
|High-speed lock stitch sewing machine|
Tuesday, September 23, 2014
Sewing threadsAlmost all garments produced have one component in common: the sewing thread. Whilst sewing threads are usually a relatively small percentage of the cost of a garment, they have an extremely significant influence on the appearance and durability of the finished product. The production of sewing threads is an extensive and complex subject.
In practical terms, any examination of sewing threads must start with the question, what are the essential requirements of sewing threads? The answer can be grouped under two headings, sew-ability and durability.
This describes the basic all-round properties of the thread, including –
a. Not breaking when used for high speed sewing.
b. Facilitating the consistent formation of stitches.
c. The minimum occurrence of skipped stitches.
d. In order to prevent changes in tension during sewing, the thread must have a uniform diameter.
e. A high level of resistance to abrasion is essential due to the friction of the thread in the needle eye and with other mechanisms.
f. The thread has to have sufficient surface smoothness to pass easily through the guides on the machine. This ensures the uniformity of stitch formation.
The main thread related factors under this heading are –
a. The thread has to have sufficient elasticity to withstand the normal pressures imposed on seams during wear. This is particularly important for knitted fabrics because of their inherent extensibility.
b. Thread shrinkage should minimal after the garment has been washed or dry-cleaned. Seam puckering is often caused by unstable thread.
c. It is important the thread maintains its original color after being subjected to cleaning processes. In particular, this applies to the threads used for top stitching and other decorative purposes such as embroidery.
Ideally a sewing thread should combined the best properties of sew-ability and durability, and whilst there are many threads available which approach this, certain compromises have to be accepted due to various technical limitations. However, for practical purposes sewing threads for the clothing industry can be divided into three broad groups: Cotton, Synthetic and corespun.
Threads made from cotton fibres have excellent sewability because the fibres are very supple and are not seriously affected by the heat generated by needles during sewing. On the other hand, cotton threads are not highly durable and some of the softer types have a tendency to shrink when the garment is washed. Glace and mercerized cotton threads sew well and have a lustrous appearance, but they both shrink slightly when wetted.
This is a large group of threads made mainly from nylon, polyester, rayon and polyamide filaments or fibres. The threads are very durable and are not affected by moisture or the chemicals used in washing powders or dry cleaning solvents. In addition, they have excellent dimensional stability and a high level of resistance to abrasion. Synthetic threads are available in a number of different constructions and finishes, which enhances their performance for special sewing applications.
This thread has a continuous filament polyester core wrapped in cotton fibres, which produces a strong thread with excellent sewability.
Corespun threads have good elasticity and a high resistance to heat and shrinkage, but cost more than regular threads because they have to be dyed twice, first for the polyester core and then for the cotton wrap. An advantage of corespun threads is that finer threads can be used due to the superior strength of the polyester core.
Two other natural fibre threads which have limited applications are silk and linen.
Silk – These threads are strong, with good elongation and a highly lustrous appearance. Silk threads have good sewability but the high cost restricts their use for mass production sewing.
Linen – Once widely used for sewing tents, shoes, leather etc, threads spun from flax have been mostly replaced by synthetics.
There are many systems for defining thread size but the most widely used is the Tex number system. This is based on the gram weight of 1000m of yarn, so a fine thread would have a low Tex number and a thick thread would have a high number. Thread manufacturers using other systems will normally provide the Tex equivalent values.
Price is not necessarily the sole criterion for purchasing sewing threads because it is performance which really counts. Trouble-free sewing combined with durability is essential to prevent constant work stoppages caused by continual breaks, and to avoid consumer dissatisfaction with seams that open during normal wear conditions.
Effective sewing can only be achieved when there is an accurately balanced combination of all the components involved. It is said that the real strength of a chain is that of its weakest link, and this also applies to sewing.
Monday, September 22, 2014
Construction of a sewing needleNeedles have been used for hand sewing since about 18000 BC and were originally made from ivory, bone, wood and horn. Their form has remained unchanged since then. During the fifteenth century iron needles were introduced for hand sewing, and in 1800 Balthasar krems of Germany was the first to use a needle with the eye near the point for a chain-stitch machine he had developed. The large scale production of sewing machines started about 1840 and this was paralleled by numerous developments in the manufacture and quality of machine needles. Today the steel needle in common use is a precision product which is critical to the formation of stitches.
The functions of the sewing machine needles are to form of a passage in the material through which the needle thread can wholly or partially pass and form a loop which can be picked up by the looper or hook mechanisms. Needles are made in straight or curved forms and their main construction features are –
Butt - The truncated conical shape at the top of the needle which facilitates its insertion into the needle bar or clamp.
Shank – Usually larger in diameter than the rest of the needle, the shank can be cylindrical in shape or flat on one side, developing on the method used to secure the needle in or on the needle bar.
Shoulder – The selection joining the shank to the blade.
Blade – The longest section of the needle, this runs from the shoulder to the eye.
Grooves – On one side of the needle there is a long groove which protects the needle thread as it enters and is withdrawn from the fabric. There is a short groove on the opposite side which extends a short distance above and below the eye and its purpose is to aid the passage of the thread into the material and loop formation.
Eye – An elliptical hole between the two grooves; the shape and finish of the inside top of the eye are important factors in the prevention of thread damage during sewing.
Point – This is shaped to provide the best penetration of the material being sewn.
Tip – The tip, when combined with the point, determines the ease and extent of penetration into the fabric.
Points and tips have a decisive bearing on the performance of the needle and the various types of combinations can be divided into two groups –
Points and tips have a decisive bearing on the performance of the needle and the various types of combinations can be divided into two groups –
Round Points – These are used for the sewing of textile materials and whilst they all have a circular cross section, they differ in their tip shapes. In general, set point needles are used for most woven fabrics and the ball point needle is preferred for delicate and knitted materials. Both these points are available with light, medium or heavy tips and these combinations allow for good compatibility between the fabric and the needle.
Cutting points – These needles actually cut a hole through the material and because of this are mainly used for the sewing of leather, artificial leather and plastic materials. The points come in a variety of shapes. They all influence the set of the stitches and as a result the appearance of a row of stitches. The individual stitches are slightly slanted instead of being in a straight line.
Tuesday, September 2, 2014
Definition of Seam puckerSeam pucker is the most common problem to the making-up trade. It is a problem that also concern fabric finishers, sewing machine manufacturers and sewing thread manufacturers. This problem has been magnified with the introduction of new and unconventional fabrics and finishes.
The common factors which relate to seam pucker are the type of fabric yarns, construction of fabric, type of sewing machine, stitching conditions, sewing thread behavior etc.
Practically it is very difficult to avoid seam pucker, because there must be some buckling along the seam line. Although there is no standard level of acceptability, but we asses the seam pucker visually and it is all a matter of degree. If visually a seam appears to be free of pucker it is acceptable, although technically pucker may be present. The visible effects of pucker can be reduced but cannot be eliminated completely.
Basically there are four type of seam pucker, their probable causes and remedy is discussed briefly below.
The main cause of this type of seam pucker is “Structural jamming” means displacement of fabric yarns by sewing thread results crowding tightly around each stitch. The severity of this condition depends on closeness of weave or knit, fibre characteristics and fabric finishes. Natural fibres are less prone to structural jamming than synthetics. Certain fabric finishes also affects in this regard. Its severity is directly related to sewing thread size and stitch density. Use of multiple needles worsens the condition because of the greater number of penetration. The chain stitch seam is less prone to this type of pucker than lock stitch seam.
Seam pucker due to structural jamming could be tested easily by preparing a seam along the warp and then cut every stitch on face and back. If the pucker does not disappear, then it is due to structural jamming.
Some improvement could be made by changing, where possible, to a finer needle and thread and reducing the number of stitches per unit length. Sewing slightly at a bias angle respective to fabric yarn also works.
This type of pucker appears due to differential feeding of top and bottom plies of fabrics. There are many causes of differential feeding but the two main causes are –
a. The limitation of the simple drop feed mechanism to transport two or more plies of fabric through the sewing machine wholly by mechanical means.
b. In case of smooth surfaced fabrics, slippage of one ply of fabric against other during feeding in sewing machine.
The seam pucker due to differential feeding could be detected by a simple test. Two pieces of fabrics marked in one centimeter intervals, after seaming, (if marking matches and pucker appears then it is due to other reason) if marking does not match and pucker appears, then it is due to differential feeding.
There are special machines with puller feeds, compound feeds and other improved feeding mechanisms which help to reduce feeding pucker. If conventional drop feed machines are used then the following precautions will be found helpful –
a. Where different types of fabrics are joined together, less extensible fabric should be on top.
b. Use of fine and sharp-toothed feed-dogs.
c. Proper setting of the pressure of the pressure foot to obtain satisfactory needle penetration through the fabric.
d. If the back of the feed dog is slightly lifted up to create a pulling effect away from the needle, then it works in most cases.
e. Re-setting of the feed timing so that the material is completely at rest while the needle is touching the fabric.
Another technique also works, if the operator adopt a nip and run sewing technique, that is, the seam should be nipped by the forefinger and thumb of the left hand just behind the pressure foot and similarly by right hand at a suitable position in front of the pressure-foot.
Unnecessary high tension of the sewing threads is the main cause of this type of seam pucker, although the effect may not be visible immediately after seaming. The stretch of the cloth during its manipulation by the machine operator also contributes to this fact. The usual methods of reducing tension pucker are –
a. By setting the thread tension as light as possible so that machine can produce a satisfactory balanced stitch.
b. By making sure that the machine is working properly.
Thread shrinkage Pucker
A sewing thread should possess the same shrinkage property as the fabric into which it is stitched. If the sewing thread used is dimensionally unstable in washing or wetting or permanent pressing or hot box laundering, then the seam pucker may be visible due to sewing thread shrinkage. This problem mainly arises when cotton thread is used.
To avoid this type of defect, it is better to use spun polyester threads which are dimensionally stable in washing, wetting and at temperature up to 150o C. Cotton thread with special finishes may also be used. If cotton threads are required to use, a slight looseness of stitches is necessary to compensate for thread shrinkage when wet.
Monday, February 17, 2014
Different feed systems | Basic functions | Necessity of sewing m/c feed mechanisms
Feed systems relate to the combination of the needle, throat plate, and pressure foot and feed dogs which control the feed of the material from stitch to stitch whilst regulating the relationship between the plies being sewn. Some examples are given here-