pressing..ppt

PRESSING

• Pressing is the application of heat, moisture, and pressure to shape, mould, or crease fabrics, garments, or garment parts into the geometric forms.

• Pressing may be done:

(a) During assembly to facilitate other operations and improve quality.

(b) Final finishing process.

ELEMENTS OF PRESSING

• The three elements of pressing are:

(1) Heat

(2) Steam

(3) Pressure

HEAT

• Heat is needed in most pressing processes to soften fibres and stabilize and set the desired shape.

• Temperatures must be selected to suit the fibres, yarns, and fabrics used in a particular style.

• Sources of heat include heated surfaces and steam.

• Steam (moisture) is the fastest means of transferring heat into the fabric.

• Heating water in a pressure boiler creates steam

STEAM

• Higher the pressure, hotter and drier the steam.

• Effective use of steam reduces the time for pressing and the amount of pressure required to shape the garment.

• Different fabrics require different amounts of moisture and heat.

• Amount and dryness of the steam are critical to the effectiveness of the pressing operation.

• Excessive moisture may cause shrinkage and colour bleeding

• Pressure is applied to alter shape and increase the permanency of the moulding or creasing.

PRESSURE

• Too much pressure may distort fabric surfaces, flatten textures, and create permanent garment and/or fabric damage.

• Pressure may be applied by a mechanical device or by steam.

• Mechanical pressure requires a combination of solid surfaces such a tables, bucks, or irons to mould the garment.

• Mechanical pressure is specified by the amount of force per unit of time.

• When a buck press or shaping device is not used, air or steam pressure depends on the shape of the garment.

• Air or steam is blown into the garment to expand to its full size, while heat and/or steam are

• Moisture and heat are extracted by the use of a vacuum return system that extracts steam as it penetrates the fabric.

• The vacuum pulls the steam through the fabric, thus drying and quick cooling the fabric to set the new shape.

• In the 1890s, men’s suits were pressed with gas‐fed irons weighing as much as 20 pounds.

• Gas was fed by a rubber hose to the centre of the iron and then ignited to produce heat.

• With this system, a presser could press 10 men’s suit in a 10‐hour day.

Factors Affecting Elements Of Pressing

1. The types of material used.

2. The shape or form that is required in the final garment.

3. The degree of permanency needed.

OBJECTIVE

1. To smooth away unwanted creases and crush marks

•In garment manufacturing – accidental creases ‐ from mistakes in previous under pressing; crushes from handling by no. of operators or from tightly tied bundles

2. To make crease where the design of the garment requires them

•Creases – design features in garments (series of creases – pleating)

•Pressing – hems and cuff edges, front edges, top edges of waist bands, pocket flaps and patch pockets edges.

3. To mould the garment to the contour of the body

•Enhancement of shape already largely determined by seams and darts (mainly effected in wool or wool rich garments)

•Chief areas where moulding takes place – ends of darts, collars, shoulders, armholes and sleeve heads and sometimes trouser legs

4. To prepare garment for further sewing

•Under‐pressing – pressing operation on partly constructed garments

•UP – also makes further sewing easier to do, or easier to do to a high quality std.

5. To finish the fabric after manufacturing the garment

TYPES

There are two types of pressing-

1)- In-Process pressing

• In‐Process pressing, or Under Pressing, is done while a garment is under construction.

• It is used to crease, shape, and/or smooth components for more accurate seaming.

• Sharp edges on garment components increase accuracy in sewing

2)- Off- Pressing

• Finish Pressing, or Off‐Pressing, adds the final shape to seams and garments.

• The time, , temperature, pressure, and types of mechanical devices used for pressing depend on:

(1) Types of materials used.

(2) Shape or form that is desired in the final garment.

(3) Degree of permanency needed.

• The equipment used for pressing is designed to control the heat, moisture, and pressure applied during the pressing operation.

• Some equipment is designed to mould or set a special shape into the garment.

PRESSING EQUIPMENT

Solid‐surface pressing equipment uses a firm surface to apply pressure, while steam and heat mould the fabric, garment, or garment, parts.

Pressure may be applied through rolling action, gliding action, or compression.

Solid‐surface pressing equipment consists of buck presses, irons, blocks, dies, rollers, collapsible forms, and creasing and folding blades.

Types Of Pressing Equipments

1. Buck presses.

2. Iron pressing.

3. Block or die pressing.

4. Form pressing.

5. Steamers.

6. Steam tunnels.

BUCK PRESSING

• These are commonly used by manufactures of slacks, skirts , and jackets.

• Components-1. Lower buck

2. Moveable head with a linkage system

3. Buck padding stem and vacuum system frame

4. Manual or automatic control for steams, vacuum, heat and pressure.

• It may be used for in-process pressing & finish pressing.

Buck Pressing Machine

IRON PRESSING

• It is a manual molding operation in which pressure and heat are applied with a flat contact surface.

• Components of iron pressing-1. Iron

2. Power line.

3. Bed buck.

4. Iron support system.

5. Steam and vacuum system.

• It is used extensively for in-process pressing and for shaping components parts , as well as final pressing

BLOCK PRESSING

• It is a molding process that establishes a products conformance to a form.

• It may change the surface characteristics and dimension of a product.

• The fabric is placed on a fixed form before pressure heat and steam is applied.

• It is used to crease patch pockets and pocket flaps.

Buck Press Machine

FORM PRESSING

Form presses are made in the approximate shape of the finished garments.

Steam is forced from the inside of the form through garment while the form expands to fill all the space inside the garment.

It is designed to reduce the amount of positioning and re-positioning time.

Form Pressing

STEAMERS

• These are the pressing machine that uses only steam to mold and smooth the garment.

• Types of steamers-1. steam jets.

2. steam guns.

3. steam puffs.

4. steam tunnels.

• These devices may be used either to form and stabilize garment shape.

Steamers

Steam Tunnels

• These are used for final pressing.

• Garments are de-wrinkled within a chamber by the average pressure of circulating steam.

• Garments are carried over the nozzle of a steam jet in order for the garment to receive the full force of the steam pressure.

• It reduces labor costs and process garment at a rate of 1200 to 3600 units per hour.

TECHNOLOGICAL ADVANCEMENTS IN PRESSING

Advancements in finishing technology focus on several areas-

Greater versatility.

More precision in determining exact pressing requirement of fabrics and finishes.

Improved quality.

Energy saving

PNEUMATICS IN THE PRESSING ROOM

Plant engineering for the functioning of the pressing machines in the garment industry, apart from the electric parts, concerns the fluids necessary to run the machines, namely pneumatic air, steam and vacuum. It must be kept in mind that without these fluids, a pressing machine cannot work.

Generally, there is a mentality to consider an ironing table as self contained,i.e.,with a built-in vacuum.This may be applicable, for example, in in-line preparation (sewing dept) where it could be awkward to have main vacuum pipes connected to each and every table.

Centralised vacuum plant

Centralised air compressor room

In a centralised vacuum plant, one motor provides vacuum to 40-50 tables, implying money saved in power and almost trouble-free maintenance.

There are machines which require up to 300 cubic metres ofair per hour and it is unthinkable to have a single source of vacuum per machine, which could prove too costly and toonoisy. The noise is due to vacuum motors which are far from silent and are usuallyplaced in the so called ‘power room’ to avoid any noise pollution inside the factory.

Vacuum pipe in the pressing room

It is used mainly for operating:

• Advanced features in modern machines • Pneumatic tools• Cooling systems • Sewing Workstations • Air curtains• Vacuum cleaning systems• Overhead material handling• systems, etc.

It does work and this work energy must be related to air supply, its volume and its pressure.

COMPRESSED AIR

Pneumatic cylinders

PressureNormally air at atmospheric pressure(1 Bar) is compressed mechanically to ahigher pressure of 5 to 13 Bar.

Factors causing excessive pressuredrops are improperly sized air pipes,inefficient pipe layout, pipe scaling,corrosion and material.Pressure drop causes compressors towork harder and thereby consumemore energy.

When compressed air moves within apipe, losses are incurred due to frictionand turbulence. Rough surfaces causemore turbulent air flow and higherfriction. These line losses in a particularcomponent are expressed as pressuredrop.

Distribution

Pneumatic distribution systems

The vacuum units can beconnected in series or in parallel.

There are various machines which produce compressed air. The most utilised types in the clothing industry are:-- reciprocating compressors-- vane rotating compressors-- screw rotating compressors

Vacuum pipe Steam line

Pressing machine in operation at Silver Spark, Raymond

The choice of one of these types isrelated to the quantity of air requiredand to its pressure.

Flat Bed Press PneumaticHead is suspended on rocker arms for self aligning with the bed.Machined pressing surface. Pneumatic raising and lowering with push buttons. Perforated bed prodded with sponge padding. Powerful centrifugal suction for moisture exhaust.Automatic timed release of the head at preset time. Automatic digital temperature control of the head.Heating Steam Electric - 0.5" BSP 15 KWAir Consumption - 100 LTS/MIN

Electro-Pneumatic Pressing Machine

Machine does the pressing itself, automatically. Operator only settles and gets it out. One person can operate on two machines at the same time. When the first machine starts pressing operator settle down clothing on the second one and will just push a button to start pressing.

Steam Pressure  3-4 barSteam inlet  1/2" Condense outlet  1/2" Vacuum connection  2" Air pressure  6 bar Air inlet  1/2“ Electrical inception  220/380 V

•ironing board for the finishing of jacket, coat, overcoat linings. •Due to strong vacuuming very quick ironing is achieved. •Using the water pistol for humidifying the lining is an easy way of ironing when the process is mode with an iron without steam and electricity. Electricity 380 V Motor Power 0.37 kW heating Power 1.5 kW Capacity 30 Jackets

Pneumatic Ironing Board

Ironing Machine With a Cover Pneumatic Central System

Used especially for ironing wool pull-overs. Due to the electro pneumatic system pressure steam, vacuum, staying closed time may all be regulated by buttons. Energy saving is achieved since it is not heated by electricity. Works with central steam, vacuum, air and 220 Volt electricity. Vacuum Motor  Central System Steam Pressure  4 bar Air pressure  6 bar Steam inlet and outlet  1/2" Vacuum Outlet  2" Steam Consumption  50 kg/h Air Consumption  90 kg/h Capacity   40 unit/h

BIBLIOGRAPHY Books referred:

1. Apparel Manufacturing Handbook: Analysis, Principles and Practice: Jacob Solinger

2.Carr and Latham's Technology of Clothing Manufacture

Sites Referred:

1.http://www.energymanagertraining.com/equipment_all/boiler/pdf/0507CoalFiredBoilers.pdf

2.http://209.85.129.132/search?q=cache:WfqBQjs3ze8J:www.energymanagertraining.com/equipment_all/boiler/pdf/0507CoalFiredBoilers.pdf+coal+fired+boilers&cd=1&hl=en&ct=clnk&gl=in&client=firefox-a