spreading and cutting machinary
Post on 10-Apr-2015
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SPREADING
AND
CUTTING MACHINARY
(S.P.ME.)
By:-Aeasha
Devanu Roy ChoudhuryIshan RastogiMona Kumari
(B.F.Tech. Sem-IV)
Spreading
Spreading is the processes of superimposing lengths of fabric on a spreading table cutting table or specially designed surface in preparation for the cutting process.
A spread or Lay-up is the total amount of fabric prepared for a single marker.
Methods:-1. Spreading By Hand2. Spreading Using A Travelling Machine
Spreading By Hand
• Time consuming method• Require operator on each side of table• But necessary for spreading some typical fabrics, like
o Checked fabricso Fabrics with crosswise stripeso Fabrics with regular repeating patternso Fabrics with a repeating design at intervals of a garment
length
Spreading Using A Travelling Machine
Spreading machines carry the piece of fabric from end to end of the spread, dispensing one ply at a time.
Components of spreading machine:-o Frame or carriageo Wheels travelling in guide rails at the edge of the table
o A fabric supporto Guide collars to aid the correct unrolling of the fabric.
Working:-o In the simpler version, the operator clamps the free end
of fabric in line with the end of the spread,o Then pushes the spreader to the other end,o Cuts off the ply in line with that end,o Clamps the beginning of the next ply,o Pushes the spreader to the other end and so on.
Cutting:-
Manual Cutting Machines
Fabric Scissors
o Used to cut only single or double plies.o Appropriate for made-to-measure garments/tailor made
garments.o Can cut any fabric type & pattern shape.o Blade length- 8"-14"
Advantages:-1. Very portable2. Easily available3. Easy to handle4. Suitable for both left and right handed people5. No electricity required
Disadvantages:-1. Time consuming2. Need muscular power3. Requires a lot of skill4. Very low productivity5. Not suitable for mass production
Straight Knife
Advantages:-1. Easily available2. Cheaper3. Can be used for various types of fabrics & styles4. Knife blades are easily available & replaceable5. Have the option of changing the blade size within a machine
Disadvantages:-1. Problem with sharp turns2. Not very safe for the operator3. It has a issue of grip on the fabric (stretchable fabrics)
STRAIGHT KNIFE:
Blade length - 4 to 14 inches. Induction motor, ¼ HP, 220 volts.
2850 rpm.
Blade holder for the blade to rest.
Auto sharpening device – Grinding belts.
Manual lubrication system.
Round Knife
Advantages:-o Larger surface area in contact with the fabric, so better grip.
Disadvantages:-o Ply cutting is staggered (not uniform in all plies)o V-necks, scoop necks, steep curve cutting is almost impossible.o Knife clearance area (KCA) required is very higho Lay height should not be more than the radius of bladeo Costlier than straight knifeo Changing of blade is difficult
ROUND KNIFE:
Blade diameter – 4 to 8 inches. 2850 rpm.
Auto sharpening device – Grinding stone.
Band Knife
Advantages:-1. Speed is high2. Precision cutting3. Easier to cut very small pieces of pattern4. Cutting of single layer or multiple layers can be done easily5. Mitering of shirts, etc is done using this
Disadvantages:-1. Expensive2. Supportive infrastructure is required, which adds to the cost3. More space is required4. Safety is a major issue5. Maintenance is difficult comparatively
BAND KNIFE:
The knife rotates on 3 blades. Works in single and 3 phase.
Blade thickness – 0.45mm.
Blade width – 10mm.
Blade length – 3500mm.
Maximum layer cut – 12.
Die Cutting
Advantages:-1. Very high precision cutting2. Easily available3. Cost is low
Disadvantages:-1. Cannot be used for very dense fabrics2. Cannot be used for knits & leather like fabric with woven base3. With every style & size change, a new frame is required
Machine Specification And Details
There are 3 types of blades available:
Fine edge Medium edge Coarse edgeUsed mainly for silk, synthetic, knits and loosely woven fabrics.
Light woollen, polyester, men’s suiting fabric and velvet.
Heavy weight cotton, twill, lining, tightly woven fabrics, denims, soft leather, and vinyl rubberized materials.
Blade material is generally high carbon and high speed steel.
Newer technologies are being developed for blades as well, listed below are:
o Teflon coated blade: To avoid blade heat up.
o Grooved blade: Grooves on the blade provide air for cooling, grip the fabric in a better manner.
Die Cutting Method :-
1. Cutting is done through shear hydraulic press.2. Used for non woven and leather in shoe industry.
Advantages of die cutting:
Cheaper. 100% accurate cutting.
Can be used for larger patterns also.
Easily available.
Disadvantages of die cutting:
Cannot be used for very dense materials. For every change in style and size a new template
has to be developed.
Fully Automatic Cutting Machines
Advantages:-1. Very high speed2. High productivity3. Cutting is done on cutting table, so the spreading table is free
for new spread of lay4. Man skill required is less
Disadvantages:-1. Cost is very-very high2. Extra infrastructure required3. Lay height is less4. Very accurate feeding of fabric needs to be done
Computerised Cutter
1. Table with a cutting surface of nylon bristles.2. Nylon bristles support the fabric lay that are flexible enough to
permit penetration & movement of the knife blade.3. Nylon bristles also allow the passage of air through the table to
create a vacuum, reducing the height of the lay & holding it in place.
4. Knife blade is supported on the top.5. The carriage supporting the cutting head has 2 synchronized
servo motors which drive it on tracks on the edges of the table.
6. A sheet of air tight polyethylene covers the top of the lay which assists in creation of vacuum & allows significant compression of the lay.
7. A control cabinet houses the computer & the electrical components required to drive the cutter, its carriage & the vacuum motor.
Laser Cutter
Laser cutting works by directing the output of a high power laser, by computer, at the fabric to be cut. The material then either melts, burns, vaporizes away, or is blown away by a jet of gas, leaving an edge with a high quality surface finish.
Principle A laser produces a beam of light which can be forced onto a
very small spot (O.25mm), producing a very high energy density. The energy transfers to the material upon which it is focused, producing a rapid increase in temperature.
Cutting takes place by vaporization. Charring of the fabric is prevented by the use of a jet of inert
gas which also removes debris & smoke from the cutting area. A laser beam does not become blunt but it does suffer with
limited depth of focus.
Laser cuts with incredible speed.
Waterjet Cutter
A water jet cutter, is a machine capable of cutting fabrics using a jet of water at high velocity and pressure, or a mixture of water and an abrasive substance.
The cutter is commonly connected to a high-pressure water pump where the water is then ejected from the nozzle, cutting through the material by spraying it with the jet of high-speed water. Additives in the form of suspended grit or other abrasives, such as garnet and aluminium oxide, can assist in this process.
An important benefit of the water jet cutter is the ability to cut fabrics without interfering with the material's inherent structure as there is no "heat-affected zone" or HAZ. Minimizing the effects of heat allows fabrics to be cut without harming or changing intrinsic properties.
Water jet is considered a "green" technology. Water jets produce no hazardous waste, reducing waste disposal costs. Water jets use very little water (a half gallon to approximately one gallon per minute depending on cutting head orifice size), and the water that is used can be recycled using a closed-looped system. Waste water usually is clean enough to filter and dispose of down a drain. The garnet abrasive is a non-toxic natural substance that can be recycled for
repeated use. Garnet usually can be disposed of in a landfill. Water jets also eliminate airborne dust particles, smoke, fumes, and contaminates from cutting materials such as asbestos and fiberglass. This greatly improves the work environment and reduces problems arising from operator exposure.
Commercial water jet cutting systems are available from manufacturers all over the world, in a range of sizes, and with water pumps capable of a range of pressures.
Plasma Cutter
Plasma cutting is done using a plasma torch. In this process, an inert gas (in some units, compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the fabric being cut and moves sufficiently fast to blow molten pieces away from the cut.
The machine has small footprint, increased flexibility, optimum safety, faster operation.
Ultrasonic Cutting
The ultrasonic cutter allows its blade to vibrate ultrasonically, enabling the blade to cut a wide range of materials.
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