PRODUCTION PLANNING AND MATERIALS CONTROL
Production planning and Material control
Production planning and Material control Defined as the technique of foreseeing every step in a long series of separate operations, each step to be taken at the right time and in the right place and each operation to be performed in maximum efficiency. It helps entrepreneur to work out the quantity of material manpower, machine and money requires for producing predetermined level of output in given period of time.
Objective is the organization of the supply and movement of materials and labor, machines utilization and related activities, in order to bring about the desired manufacturing results in terms of quality, quantity, time and place.
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
Fabric spreading is very important part of the production process because it is basic for obtaining a high quality final product
Requirements of spreading
1. Fabric must be flat During fabric spreading it should be maintained that the fabric is flat. The wrinkle must be removed (by air flow) so that the fabric may be flat.
2. Correct ply tension: The ply tension of the fabric should be proper. If the tension is low, there will be ridges in the plies and if the tension is too high, the fabric may shrink after cutting and sewing.
3.Alignment of fabric ply: Fabric spreading is done according to length and width of marker. Every ply should comprise at least width of the marker plan. but should have the minimum possible extra outside those measurements 4.Correct ply direction and lay stability: These two factors depend on fabric type, pattern shape and spreading equipment's that are available. When the pattern pieces have been positioned in a particular direction in the marker plan, it is the essential that the fabric is spread according the direction. Symmetrical patterns pieces are placed in the same way up or face to face.
5. Elimination of static electricity: If spreading is done by manmade fabrics, static electricity may generate. It can be eliminated by reducing friction or increasing humidity of the room. Anti-static paper may be used to reduce the static electricity generation. 6. Elimination of fabric flaws: The flaws of fabric must be indicated during spreading and necessary steps to be taken to remove these faults. The general two steps to remove the flaws are : Splicing Over lapping
7. Easy separation of the cut lay into bundles: The size of cut lay into bundles of fabric depends on the height of fabric lays. Some low priced color papers are used in the fabric plies to displace. It helps each bundle to prevent shade variation for displacing. It also helps to catch the slippery fabrics lays during spreading. Generally, the colored papers are rough in surface.
9. Avoidance of distortion in spread: 8. Avoidance of fusion of plies during cutting: The heat generated when the fabric lays are cut by using cutting knife due to the friction fabric and knife. Generally, those fabrics are melted due to heat generation to the fabric lays which are made by thermoplastic fibers. To prevent this defect, some anti-fusion papers are used with the gaps of fabric plies during spreading. 9. Avoidance of distortion in spread: The fabric may be creased and folded due to the friction in the bottom of lay by base plate of knife during cutting with straight knife or shifting of fabric lay. As a result, defected pattern may occur. To remove this defect, fabric lay is made on the smooth paper so that, there is less possibility of friction between fabric and table.
10. Matching checks and stripes: For check and stripe fabric, the flaws of fabric must be indicated during spreading and necessary steps should be taken. Marker planning should be done by matching with stripe of check of fabric. Each ply should be correct during spreading on the other for making fabric lay. Then the matching may warp or weft way as required.
Spreading equipment Spreading surfaces ( table, pin table, vacuum table) Spreading machines
Manual spreading fabric is drawn from its package which, if it is a roll, may be supported by a frame and carried along the table where the end is secured by weights or by clamps. The operators work back from the end, aligning the edges and ensuring that there is no tension and that there are no wrinkles.
Machine spreading Spreading machines carry the piece of fabric from end to end of the spread, dispensing one ply at a time on the spread.
FASTER AUTOMATED MACHINES can spread 100-150 yards per minute.
Spreading machines may include: A motor to drive A platform on which the operator rides A ply cutting device with automatic catcher to hold the ends of ply in place A ply counter An alignment shifter actuated by photo electric edge guides A turntable A direct drive on the fabric support, synchronized with the speed of travel, to reduce or eliminate tension in the fabric being spread.
F A B R I C U T N G
Cutting Is the production process of separating (sectioning, carving, severing) a spread into garment parts that are the precise size and shape of the pattern pieces on a marker.
Fabric cutting To cut out the garment pieces from lays of the fabric with the help of cutting templates. Cutting is irreversible process in garments cutting, so it must be done carefully.
Requirements Of Cutting: Precession of cut Clean edge Consistency in cutting Support of the lay
Three methods of cutting technique: 1.Completely by manual-Hand operated scissors. 2.Manually operated powered knife. Straight knife. Band knife. Round knife. Die cutter. Notched cutter. Drill. 3.Computerized technique. Knife cutting. Cutting by water jet. Leaser cutting. Plasma torch cutting.
Hand Operated Scissor First & oldest method of fabric cutting Features: First & oldest method of fabric cutting Used for cutting one or two plies of fabric Available to cut the fabric from left to right or right to left Needs more time & contain high cost Used in tailoring & household purpose to cut fabric
Straight Knife Features: The elements of straight knife consists of: 1. An electric motor 2. Stand 3. A base plate usually on rollers 4. Handle 5. Knife 6. Knife Guard 7. Wheel Knife is driven by electric power Grinding wheel is present to sharp the knife during cutting Blade edge: straight edge, wave edge, saw edge, serrated edge Straight edge is mostly used Blade stroke 2.5 to 4.5 cm Can cut heavy fabric such as canvas & denim
Working Principal: Two kind of powers are required to operate a Straight Knife Motor power drive the reciprocating knife Operator power drives the knife through the lay The motor power needed is determined by Height of the lay Construction of the fabric Curvature of the line being cut Stroke of the blade Greater power of the motor, greater blade movement to cut the fabric
Straight Knife ADVANTAGE: Comparatively cheap & transferred easily from one place to another place Higher lay of fabric can be cut easily Round corner can be cut more precisely then even round knife Production speed is very good & fabric can be cut from any angle DISADVANTAGE: Some time deflection may occur due to the weight o the motor Knife deflection is high in risk, when lay height is too high Sometime accident may happen
Band Knife Features: Band knife comprises a series of three or more pulleys, powered by electric motor Cutting knife is endless in shape & flexible Blade is usually narrower then on a straight knife This method m/c is stationary but fabric is moveable This is like saw mill cutter
Band Knife Used when a higher standard of cutting accuracy is required ADVANTAGE: Used when a higher standard of cutting accuracy is required Extensively used to cut very sharp corners small parts such as collars & cuff Used more in men’s wear than ladies wear Intensively risk of accident is low Possible to cut 90˚ angle of the fabric DISADVANTAGE: Work load is high as m/c is stationary & fabric is moveable Not suitable for cutting large amount of garments parts Not possible to cut fabric directly Fabric wastage is high Power loss is high
Round Knife Element of round knife: Base plate & Electric motor Features: Element of round knife: Base plate & Electric motor Handle for the cutter to direct the blade Rotating circular blade Blade diameter varies from 6-20 cm Blade is circular Blade is driven by electric power Circular knife is driven by 1000-3500 cm
Round Knife ADVANTAGE: Suitable for single ply cutting as well as multi-layers (say 20-30 layers) Suitable for small scale cutting Suitable gentle curve cutting Easy to operate Useful for cutting layer parts of a garments DISADVANTAGE: Not suitable for cutting very curve lines in higher no. of lays Not suitable for higher production Possibility of accident is high Difficult to cut small component Needs skilled operator
Die Cutting Features: Mainly two types of die cuttings are available namely: Presses & Clickers Main parts of all die cutting m/c are Blade, Ram Head, Die, Motor & Operating System of Ram Die is made by metallic strip Most useful to cut sharp & small parts
Working Principal: Die is prepared with metal strip according to the shape of pattern Die press generally has a cutting die just penetrates the cutting pad in order that the fibers of the lowest ply are completely separated For die cutting, the spreader spreads a lay to the required placement of dies The spread is cut into sections to allow transport to the cutting pad The gap between two dies 2-3 mm are placed when die is taken to cut fabric lay
Die Cutting Advantage: Extensively used to cut sharp corners of small parts of dress accurately Most useful to cut at any shape or any angle Comparatively less time required Best method of cutting knitted fabric Disadvantage: Fabric loss is high due to the need of block of fabric lay High labor cost To change the style quickly is impossible Difficult to cut large components of dress
Notcher Cutting Features: Special type of cutting m/c & used in special case Used to cut notch in the edge of some components The invention of notcher m/c was done to make notch The notch can be made in U-shape or V-shape
Notcher Cutting ADVANTAGE: Special type of cutting m/c & used in special case Useful to cut small notch to the fabric Most useful to make consistency in notching DISADVANTAGE: Only used to make notch Thermoplastic fiber can not cut by this m/c Time loss Use of the m/c is limited
Drill Cutting Features: Needed to mark on the end of components of dresses especially for pocket & dart setting This m/c contains a motor, base plate, drill, & spirit level For tightly woven fabric, making of hole by drill is permanent for long In hypodermic drill some color is sprayed along with the hole so that it can easy to find the marked place
Drill Cutting ADVANTAGE: Needed to mark on the end of components of dresses especially for setting pocket & dart Make the hole permanently for long time DISADVANTAGE: Only used for making hole in the fabric especially for setting pocket & dart For loose woven fabric it can not make the hole permanently for long time
Computer Controlled Knife Cutting Features: This method provide the most accurate possible cutting at high speed Marker is not necessary to put over the fabric lays during cutting Cutting knife is oval shaped & very hard. Sharpness is also high & blade is made of stainless steel Cutting knife itself moves according to the direction of computer memory This m/c is CAM system m/c & works through CAD system
Computer Controlled Knife Cutting ADVANTAGE: Very fast cutting operation Very active cutting by computer controlled system Suitable for very large scale production Speed of can be controlled Intensity of accident is low No need of marker Fabric can be cut 6-8 times than manual method Less labor cost DISADVANTAGE: Very expensive m/c Higher maintenance cost Skilled manpower is required If correct disc is not loaded in the computer, error will be indicated
Cutting By Laser Beam Features: This method, fabric is cut by a ray of light in a very fine spot using a laser When the ray falls on a material, it generates heat on the material & cutting is done by vaporization Fabric is cut at a speed of 13 meter per min Cutting head is controlled by computer
Cutting By Laser Beam ADVANTAGE: Very fast cutting operation Can be cut in a proper line as the cutting head is controlled by computer As the fabric is cut by ray off high so that no need of sharpening operation DISADVANTAGE: Not suitable for cutting of multi-layer of fabric For thermoplastic fabric the cutting edge should be fused Very expensive cutting method
Cutting By Water Jet Features: This system, thin jet of water is passes through a nozzle in a very momentum Pressure of water is 60,000 pounds per square inch Water is worked as like as hard & sharp knife which can easily cut the fabric A catcher in the bottom of fabric lays & it used with the same speed & the same direction of water jet
Cutting By Water Jet ADVANTAGE: Higher cutting speed There is no need of knife to cut fabric so that no need of sharpening operations Better to cut hard material DISADVANTAGE: Not suitable for higher depth of lay of fabric Cutting edge of fabric is wetted by water Sometimes water spot should be seen in the fabric Need of filtering & deionization of water Need of controlling the sound of jet
Cutting By Plasma Torch Features: This system, fabric are cut by a thin through the nozzle which is made by Argon gas One or more fabric plies can be cut Most useful for cutting single ply of fabric Fabrics are cut by placing in a table, the surface (85%) of which must be place in a perforated blanked place
Cutting By Plasma Torch ADVANTAGE: Automatic torch height control system Automatic oxy-fuel gas control system Automatic torch explosion system Pneumatic band clamping Standard auto-nesting package Easily networked DISADVANTAGE: Synthetic fiber not cut Higher number of fabric lay is not cut Need higher skill operator Costly
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