Technologies of Modern Cutting Room of Garments Indsutry | Update Machines of Fabric Cutting in Garments Production

Posted by Firoz Kabir on Tuesday, June 17, 2014 0


The first stage in the manufacturing of garments is the cutting and for that pattern making is the base. Cutting is the process which cut out the pattern pieces from specified fabric for making garments. Using the markers made from graded patterns and in accordance with the issue plan, fabrics are cut to prepare garment assembly. This is the major operation of the cutting room, of all of the operations in the cutting room this is the most decisive, because once the fabric has been cut, very little can be done to rectify serious mistakes.

Fabric cutting can be defined as precise, accurate cutting of fabric according to the shapes of patterns that are kept on the lay of fabric. The task of fabric cutting is very important, because, any mistake in fabric cutting may create difficulties in further processes, sometimes it might be impossible to bring any amendment to such mistake.

Modern Technology in Cutting Room:
Metal blade or knife has been used for fabric cutting since hundred years ago. For last 50 years it is being analyzed to invent other modern alternatives of fabric cutting   instead of using metal blade. Machines which are now being used in fabric cutting are described below-

Straight Knife:
This machine is widely used in apparel industries for cutting of fabrics. The main parts of this machine are-base plate, head and handle.


Benefits from straight knife m/c:
1)Initial investment is low
2)Easy to maintain.
3)It is possible to cut lay height upto 10”.
4)It is possible to cut curve areas more smoothly than that of round knife.

Limitations Of Straight Knife M/C:

1)There might be deflection of knife during cutting due to more height of fabric lay.
2)Knife may be also deflected due to heavy weight of motor.
 3)It is not possible to achieve precise cutting with straight knife as compared to computerized knife cutter.
4) Possibility of accident.

New Modification in Straight Knife:
Today straight knife has been improved more than the earlier version. The machine has been collaborated with an arm hanging from a stand beside the cutting table and the thick base plate has been replaced with a small, thin plate. The hanging arm bears the whole weight of the motor as well as the machine. The standard that is now used also delicate than the earlier one. Because of this modification it has become easier for the operator to operate the machine more swiftly and easily.

Round Knife:
It is round shaped knife. The edge of this knife is very sharp. The main parts of this m/c are base plate, motor, handle, blade guard. The fabric cutting power of round knife is 10 times the power of straight knife with equal r.pm.
Limitations of Round Knife:
1) The lay height up to which fabric may be cut with round knife equals to only 40% of the total diameter of the blade.
2) It is very difficult to cut small pieces it round knife especially curved parts.
3) Skilled operator is required.
4) Not suitable for bulk cutting.



Band Knife:
This machine looks like wood cutting m/c and small in shape. The main parts of this machine are blade, motor,pully.The blade is moved through a definite slot upon the table. The blade of band knife cuts the lay of fabric at 90 angles.


Benefits from Band Knife:
1) Precise cutting is possible.
2)It is convenient to cut small parts.
3)Risk of accident is less than straight and round knife.
4)The use of template makes consistent cutting easier.
Limitations Of Band Knife:
1)Fabric wastage is more.
2)Not suitable for bulk production.
3)This method is not convenient  for cutting comparatively larger parts.


Die Cutting:
Die cutting is mainly of two types such as –Clickers and Presses. The main parts in every type of die cutting m/c are-blade, ram headdie,motor,the method of operating ram and the arrangement of maintaining the height of the ram.


Benefits:

1) This method is convenient for precise cutting of small parts.
2) Not so much time consuming.
3) This method is very suitable for knitted fabric.

Limitations:
1) Fabric wastage is more.
2) Not so much time consuming.
3) Labor cost is high.
4)Not convenient for cutting large panels.

Notcher:  
It is a special type of m/c and it’s uses are limited.Sometimes it is needed to cut small notches in garments where notch m/c is used.Notcher  machine has been invented only for cutting notches.U or V shaped notch can be made with this machine.There are some notches where heat can also be applied.The cutting knife is heated during making notch,which prevents yarn fraying after cutting.Notcher machines can only be used for making notches not for other purposes.


Benefits of Notcher:

i.    Special type of cutting machine used for special purpose where notch of fabric is required
ii.    Very useful to cut small notch of fabric precisely
iii.    Consistency is high during cutting.

Limitations of Notcher:

i.    Only notch of fabric can be cut which is the main limitation of this type of machines
ii.    Thermo fiber fabrics cannot be cut by this machine
iii.    Time consuming process
iv.    Limited use of this type of machines for fabric cutting in garments industry. 




Drills:
Sometimes in order to point different places, especially for placing pockets, for creating dart and so on this machine is used. It is used to create signs amid dresses. It consists of a motor, a base plate, drill and a spirit level. Drill may not be lasted for long time if the fabric is loosely woven. By using hypodermic drill tiny amount of color is scattered along the pores so that it can become easier to find out the signs.


Benefits of Drill:
i.    This machine is required to mark on the end of components of dresses, especially for setting pocket, dart and so on.
ii.    It can make the hole permanently for a long.
Limitations of Drill:
i.    Only used for making hole in the fabric, not suitable for cutting main bulk of any garment.
ii.    For loosely woven fabric it cannot make the hole permanently for a long.





Computer Control Cutting Machine:
The most powerful and productive machine it is where the methods provide the most accurate possible cutting at high speed. It is one of the modern machine which is featured with no maker is required to put over the fabric lays during cutting. The knives are oval shaped and very stiff which are made of stainless steel and having very high sharpness. Completely computer controlling is the prime advantage of this machine where knife itself moves according to the command of computer. So far, it is a machine of Computer Aided Manufacturing (CAM) and works through Computer Aided Design (CAD).
Benefits of Computer Aided Knife Cutter:
i.    It is capable to cut the fabric very fast.
ii.    Maintain maximum accuracy in cutting with the help of computer.
iii.    Suitable for bulk production in garments industries.
iv.    Controlling over the speed of knife during cutting is another most important of this machine.
v.    Defective cuttings is minimal in comparison of others cutting machine.
vi.    Knife can be moved at any direction thus fabric can be cut at any angle.
vii.    It helps to compress in lays which assist most during fabric cutting.
viii.    Possibility of accident is very low.
ix.    Without marker fabric can be cut which helps to save money as well as time.
x.    It cuts the fabrics 6-8 times faster than manual cutting machines.
xi.    A few people are required to maintain full process of cutting as a result labor cost is very low.
Limitations of Computer Control Knife Cutter:
i.    This machine is very expensive.
ii.    Maintenance cost is very high.
iii.    Few workers are required but these people should be highly skilled.
iv.    Due to incorrect command in computer with different styles, big problem might be arisen.


Plasma Cutting
After the invention of the TIG welding process during World War II it didn’t take engineers long to develop a similar process to be use for cutting.  Instead of using a tungsten electrode to fuse metals together and inert gases to protect it from oxidation, plasma cutting uses a tungsten electrode to melt the metal and a high-pressure inert gas to remove the melted material and an inert gas to protect it from oxidation.  This process was first used by Union Carbide in 1957.  

Advantages of Plasma Cutting versus Oxyacetylene Cutting

a.  No preheating is required.
b.  Faster cutting, a plasma cutter can cut 100% to 700% faster than oxyacetylene cutting. 
c.  Less heat is spread throughout the material resulting in less warping and twisting of the material. 
e.  The increase of cutting speed cuts costs by 40 to 90 percent. 
f.  The ability to cut nonferrous metals (aluminum, stainless steel, etc.), accurately and without oxidizing the ends of the metal.

Types of Plasma Cutters and Gases


1.  Mode of Operation (How it works)

a.  A “plasma arc” is a current of electricity being carried by an ionized gas is stead of a conventional conductor.  Plasma is also considered the 4th state of matter, the first three being solids, liquids, and gases. 
b.  Using the plasma arc and a high-pressure gas to direct the arc through a constricted opening, it becomes a very useful cutting tool.  The plasma arc melts the metal and the gas pressure blows the melted metal away.  Using an inert gas for pressure will prevent the cut areas from oxidizing.  For most ferrous metals, compressed air works just fine, nonferrous metals the inert gas is essential to prevent oxidation. 

2.  Types of Plasma Cutters

a.  Transferred – In the transferred system the arc is completed by making contact with the workpiece. 
b.  Non-transferred – In the non-transferred system the arc is completed by making contact with nozzle, it can produce an arc without touching the grounded workpiece and can be very dangerous. 

Types of Gases

a.  Primary Plasma Gas – used to create the plasma arc

1)  Nitrogen – Is a mixture of 30% hydrogen and 70% argon mixture. 
2)  Argon 
3)  Hydrogen
4)  Compressed Air (The most common type used in high school Ag Mech shops.)

b.  Secondary Shielding Gas – used to protect the cut metals from oxidation. 

1)  CO2
2)  Compressed Air (The most common type used in high school Ag Mech shops.)

Safe Use of a Plasma Cutter


1.  Safety is a very while using a plasma cutter, it can cut through a person’s clothes, skin, and bones just as easily as it can cut through stainless steel.  A non-transfer type of plasma cutter does not need to be grounded to create a plasma arc.  Extra safety precautions need to be taken if you are using this type of plasma cutter.  Be sure to read the manufacture safety precautions before using their plasma cutter. 

Operating a Plasma Cutter

1.  Set the amperage and gas pressure to the manufacture’s specification.  The metal thickness, type, and type of gas being used should be considered. 
2.  When making straight cuts, use a straight edge guide.  Steady you elbow or forearm on the worktable or workpiece while cutting. 
3.  Use at least a #9 gauge or higher welding helmet while cutting with a plasma cutter.  The plasma arc is just as bright as an arc using for TIG, MIG, or Arc welding.
4.  To start your cut, move the plasma torch into position.  Cover with your welding helmet and press down on the start button.  The arc will appear when you press down on the button, move the arc along the marked area where the cut is to be made.  Keep a working distance at least 1/8" and up to3/16", the distance between the workpiece and the nozzle. 
5.  After the cut is made, inspect the cut for slag, rough areas, and uncut areas.  Adjust travel speed and amperage accordingly. 

Activity:
1.  Demonstrate the proper set and shutdown procedures, according to the manufactures’ recommendations.
2.  Use the owner’s manual, take apart the torch and show students the different parts of a plasma torch. 
3.  Demonstrate cutting mild steel, stainless steel, and aluminum with the plasma cutter. 
4.  Have students make cuts using the plasma cutter.

About the Author

Md. Firoz Kabir(M.Sc in Textile Engineering)

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