Concepts of Knit Garments Merchandising

CONCEPTS OF KNIT GARMENTS MERCHANDISING
M.R. Karthikeyan, 

Expatriate Lecturer in Textile Engineering,
Kombolcha Institute of Technology, 

Wollo University, Ethiopia
Email : srimrk@yahoo.com

Introduction:
Merchandising denotes all the planned activities to execute and dispatch the merchandise on time taking into consideration the 4 R’s of expediting Right Cost, Right Quantity, Right Quality and Right Time.

Functions of Merchandisers:

1. Execution of Sample orders
2. Costing.
3. Programming.
4. Yarn Procurement Arrangements.
5. Production Scheduling (or) Route CARD Drafting.
6. Accessories arrangement (order placing follow-ups).
7. Approval of various processors’s sewing operations and finishing processes.
8. Pattern approval (or) Dummy size set approval.
9. Size set approval.
10. Preproduction sample follow-ups.
11. Pilot run inspection.
12. In process inspection.
13. Production controlling.
14. Identifying shortages and make arrangements for the shortages.
15. Shortage quantity and quality following quality control procedures.
16. Following quality assurance procedures.
17. Maintaining the junior’s activities of in house and sub-contractor units.
18. Buyer communication.
19. Communication with production units, processing units and other third party’s (vendors).
20. Proper reporting.
21. Highlighting to the management.
22. Record maintenance (Records pertaining to merchandising).
23. Developing samples.
24. Placement of orders.
25. Taking measures for consistent production.
26. Taking preventive actions to maintain the targeted Performance level in all areas of merchandising.
27. Attending meetings with superiors and furnishing the required details about merchandising.

1. Sample order execution:
After the receipt of the Specification, pertaining to the sample order, the merchandiser has to
understand what the requirements of buyers are. Sometimes there may be amendments related to any of the specifications in the sample order sheet. It is the duty of the merchandiser to execute sample order and dispatch on time the “Right quality.”

Knit garment

2. Costing:
The merchandisers should know the following details while costing.

• Yarn cost.
• Process cost (Knitting, Bleaching, and Raising etc.)
• Rates pertaining to various sewing operations.
• CMT(Cut Make Trim) Rate.
• Ironing charges, packing charges and accessories rate.
• Overheads.
• Shortage (or) wastage 3%.
• Free on Board (FOB) (Transport charges) 2% to 3%.
• Insurance 2%-3%,
• Buyers’ agents commission 5%-6%,
• Quota rate per garment.
• Profit 15% - 20%

3. Programming:
Most probably programming is done by production manager. In some companies it is done by the
merchandisers. The following factors should be considered in programming.

1. Allowances:

• Fabric structure
• Dia. fixation (knitting dia., calendaring dia. and compacting dia.)
• Process loss (shrinkage etc.)
• Size wise piece weight
• Extra quantity required
• Size wise requirement (dia., colour (or) combination)

4. Route card Drafting (or) Production Scheduling:
For each and every order Route card (or) Production scheduling is to be done by the merchandisers. It facilitates the merchandiser to follow up the orders in planned manner. The following details (or) aspects should be considered in drafting (or) scheduling.

• Design
• No. of sewing operations
• No.of processes
• Despatch date
• No. of Components
• Type of stitches
• Order quantity
• Production capacity of the in houses (or) sub-contractors unit and processing units.
• Prioritizing the other factors
• Targeted dates for various processes (or) stages of merchandising.
• Actual finishing date (To cross check the deviation between the planning and actual performance any stage (or) Process). Targeted dates for all the stages of merchandising should be decided. Actual dates on which a particular process (or) operation is actually done should also be entered in production scheduling. The merchandisers are accountable for the deviation.

5. Accessories arrangements:
Merchandiser has to make arrangements for the timely delivery of the required accessories to the
concerned units. Accessories requisition slip may be used for requirement purpose. The merchandiser has to cross check the actual requirements after verifying the details furnished in accessories requisition form. After the receipt of accessories quality check will be done.

6. Approvals:
Approval is an authentication of all required conformances related to a process (or) an operation. The merchandisers should know the quality parameters of various processes and sewing operations before approvals. There should not heron-conformities. Evidences for approval should be cross checked to confirm that all the approvals having made properly.

7. Approval of various processes sewing operations and finishing processes:

The various process of sewing operations and finishing process such as patter making, cutting,
sewing, ironing will be approved by the technical merchandisers

8. Pattern approvals:
Patterns should be approved for

• Measurement
• Style and fit
• Allowances
• Accuracy of pattern

If there is any non-conformance in pattern that should be corrected before it is used in production
Pattern approval samples will be received from the concerned units and approved by the approval
department (or) merchandisers, If there is non-conformance in any size sample revised sample for that size should be again submitted for approval.

9. Size set approvals:
Size set approvals are made by the approval department or) by the merchandisers. All the quality
parameters related to various processes, sewing operations have to be cross checked. The below
mentioned aspects should be considered.

• Measurements
• Aesthetics
• Process quality
• GSM
• Piece shrinkage
• Washing fastness of the piece
• Sewing operation quality
• Print (or) embroidery position
• Labeling instructions.
• Size set approval seat will be prepared in triplicate.
• Washing fastness of garment should be verified.
• Shrinkage in garment can also be verified.

10. Pre-production samples:
This samples should he submitted on time to the concerned person (Buyers, buyer agents office
buying office). All the quality parameters have to be verified. In case of non-conformances it will be
mentioned in the approval sheet by the concerned persons. Sometime we may have to submit the
revised samples after the required rectifications.

11. Pilot run inspection:
Pilot run denotes the first production garments quality parameters are verified and preventive
measures can be taken. The follow up team should do pilot run inspection to identify the various
defects and it will be rectified in production.

12. In process inspection:
In process means in between any process (or) sewing operation (or) any activities related to execution of an order. We can have procedures for frequency and adequacy. In case of major non- conformities we have to highlight the problems of quality at the right time to the right person without fail. Consistent follow up inspection is a must to confirm that all the required quality procedures are adopted by the concerned units and preventive actions are taken to enhance the performance.

13. Production controlling:
Controlling should be right from the operative level also. Efforts should be taken to control the nonconformities during production. Consistent supervision is essential to control the non-conformances. Periodical quality check should be done after an hour.

14. Shortage problem:
The merchandiser has to identify the shortages of any material that is yarn, fabric, accessories etc. right at the initial stages. After identifying the shortages steps are to be taken for the arrangement of required materials on time. In case of shortages also we have to follow the quality control and quality assurance procedure without fail. Quality of the material should not be compromised.

15. Following quality control procedures:
In some companies written quality procedures are available in quality manual. The merchandiser has to know all the procedures of quality control. In all processes and operations quality procedures should be followed very strictly. It has to inculcate the importance of procedures to subordinates, in house units (or) own units, and sub contractors.

Following quality assurance procedures:
All the required test procedures (as required by the buyer) should be followed very strictly without
partiality. Evidences for testing (test reports) tested samples, tested swatches, tested accessories) should be maintained properly. Before cutting, the merchandiser has to confirm that the concerned unit has got all the required approvals properly from the authorized person.

16. Monitoring the junior activities:
The merchandiser has to monitor his sub-ordinates. He has to teach to the subordinates about the quality procedures. He has to give instructions to them before going for factory visits. He has to discuss the various activities to be executed on a particular day. The merchandiser has to control the activities of the subordinates so that the performance of the followed team is good.

17. Monitoring the activities of in-house unit (or) sub-contractor units:

The merchandiser has to monitor the activities of in-house unit (or) sub-contractor units. He has to confirm that all the quality control procedures and quality assurance procedures are followed up properly by them (or) not. He has to inculcate the importance of adopting quality procedures to attain the planned performance level.

18. Buyer communication:
The merchandiser has to go through the faxes coming from buyers and he has to send reply on time. Sometimes he has to furnish the production status of a particular order to the concerned buyer on time. The below mentioned are some of the duties of buyer communication,

• Sample execution
• Amendments
• Comments on the send samples
• Sample order sheet
• Buyer visit
• Production status
• Sending sample, swatches, Accessories regarding the approvals.

19. Communication with others:
The merchandiser has to interact with in-house units, sub-contractors, vendors and job workers of various processing. Through proper interaction only we make arrangements for the timely supply of the required materials to the concerned persons. He has to know the production status from various units which will be helpful in proper follow and proper importing.

20. Proper Reporting:
The merchandiser has to furnish (or) best the report to the right person at the right time. He has to give reports for the below mentioned activities

• Sample execution
• Approvals
• Testing procedures
• Production status
• Programming
• Shortage details
• Inspection details arid status.
• Production status for meting etc.
• Report from inspection agencies, testing labs

21. High Lighting:
The merchandiser has to highlight the major problems in merchandising at the right time without fail. Highlighting will facilitate the superiors to take the necessary steps to tackle the problems on time. Proper decision is made due to timely highlighting.

22. Record maintenance:
The merchandiser has to maintain quality records pertaining to various buyer orders. Proper filing should he done, who can utilize the services of subordinates in record maintenance. The below mentioned are some examples.

• Sample details
• Sample Inspection Reports
• Testing Reports
• Evidence of approvals
• Proper filing (Buyer wise, order wise)
• Pattern Approval sheet/size set approval sheet (copy)
• Pilot run Inspection Report
• Fabric Inspection report
• Mid Inspection Report
• Inspection report from buying office, buying agents and inspection agencies.
• Test reports from inspection agencies and labs
• Production status reports
• Production status reports related to meetings
• Pre-final inspection reports
• Final inspection reports etc.

23. Developing samples:
Some buyers will give specifications (or) diagram (or) patterns from which you may have to develop samples. Samples may be fabric with required knit structure (or) garments with required specification. The merchandiser has to consider all the quality parameters related to the samples to be developed. In case of non-conformities in the samples developed, revised samples may be send for approval purpose. It is the duty of the merchandiser to dispatch the developed samples on to the concerned buyers by means of consistent follow-up.

24. Placements of orders:
Priority is given to Approved sub-contractors after evaluation (when the production capacity is not sufficient) order is placed to new manufacturers also orders can be placed to in-house units also. In some companies, merchandiser is accountable (or) responsible to find out the right manufacturers after proper evaluation. At the initial stages small quantity order will be placed. After verifying their performance large quantity orders will be placed. Yarn may be procured by the concerned unit (or) it may be supplied by the supplier (the main manufacturer). In case of CMT order after the confirmation of average piece weight of a particular size, processed fabric is delivered to the concerned unit by the supplier.

25. Taking measures for consistent production:
It is the duty of the merchandiser to monitor the merchandising activities in accordance with the production scheduling. He is accountable for the execution of each and every process (or) an operation within the targeted time. He has to take the necessary step for the consistent production by tackling the problems in merchandising. (e.g.)

• Quality of yarn
• Replacing good quality yarn
• Consistent arrangement for fabric
• Timely arrangements for the timely supply of accessories.
• Shortage quantities follow up.

26. Preventive actions:
Detection of defects is not only the duty of merchandiser. He has to take preventive actions to eliminate deviations in all the stages of merchandising.

27. Attending meetings with superiors:
Meetings may be conducted for general discussions about order execution (or) for implementing new systems like ISO (or) it may be a status meeting. In case of production status meeting the production details about various buyers’ order will be collected by the merchandiser from different units and will furnished to superiors. The merchandiser is accountable to answer the various questions raised by the superiors pertaining to the execution of the allotted orders.

Surface Modification of Fabrics Under Plasma Treatment

Plasma Treatment on Fabric:

The plasma-induced surface modification of textile substrates has gained increasing importance over the last few years. Probably the most advantage behind this renewed interest in plasma technology is the restriction of the concentration of AOX compounds in the discharged effluents to 0.5 mg/1. The other reason for this interest is the intriguing possibility of modifying properties leading to better performance. The range of applications is diverse and modifications of surface of various materials like cotton, wool, silk, polyester have been reported.

Plasma Treatment on Fabric

Plasma treatment generally takes place in dry conditions, thus the fibers are not swollen. The changes in properties induced by plasma treatment are therefore restricted to the surface and any damage to the interior of the fiber is very unlikely.

The physico-chemical nature of the modified fibre surface has a tremendous influence on the following important phenomenon:

1. Static electricity build up and dissipation.
2. Moisture transport and comfort.
3. Oily stain adsorption and release in detergent solution.
4. Soil deposition, release and redeposition in detergent solutions.
5. Wettability and adhesion.
6. Scourability and bleachability of textiles.
7. Wettability and dyeability

Form the physical point of view, roughening of fibre surface as seen by atomic force microscopy is responsible for changes in the coefficient of friction, top cohesion, spinnability, yam strength, etc., as well as for increase in felting resistance of wool. From the chemical point of view, the oxidation of the fibre surface and interaction with polymeric materials are the main factors responsible for improvements in various properties of plasma treated materials.

Effect on Wool:
Wool is a protein fiber. It is obtained from the fleece of the sheep or lamb or hair of the Angora or Cashmere goat. The effects of a plasma treatment on wool has revolutionary changed such as anti-felting effect, degreasing, improved dyestuff absorption and increase in wetting properties. We have published a informative article on “Effects of Plasma Treatment on Wool”. You can read also.

Other changes in wool properties are summerised below :

• Plasma treatment increases the fibre/fibre friction of wool.
• Plasma treatment does not change the strength and elongation;
• The fatty matter content in wool is reduced by about one-third due to plasma treatment.
• The water content of the wool top is reduced by about 3% due to plasma treatment.
• There is changes in spinning behaviour of plasma treated wool

Effect on Other Fibers:
Plasma may be used for removing the contaminants, finishing and sizing agents from the fabric. Desizing of polyester fabric that used polyvinyl alcohol as the sizing agent can be removed by plasma treatment.

The efficiency of scouring, mercerizing etc. depends on the penetration of water into the fibre and thus its wettability The wettability of cotton and silk is increased a few fold due to its pre-treatment by N 2 plasma. In case of polyester fabrics also the wettability increases significantly.

The hydrophobic effect on a woven cotton fabric can be obtained by surface treatment. Plasma treatment with acid as a component of original gas will result in a hydrophilic surface.

Polyester fibres can be effectively modified by low pressure plasma treatment.

Soiling of fabrics is another important aspect. Treatment of polyester with air plasma considerably decreases the soiling. During plasma treatment fabrics get negatively charged. The soils are also generally negatively charged and therefore there is increased repellency.

Factors Influencing the Functions of Optical Brighteners

Optical Brighteners

The optical brighteners counteract the yellowness of the fabric by increasing the reflection of blue light rays. They convert invisible short-wave ultraviolet rays of sunlight into visible blue light and has a degree of whiteness which is comparatively more intense.

Optical Brighteners

Factors Influencing the Functions of Optical Brighteners
Optical brighteners or optical whiteners are applied to substrate as a separate after-treatment process or are incorporated into bleaching and finishing baths. Since the fluorescent brightening agents behave like dyestuffs, their efficiency and effectiveness are influenced by various factors that are important in application.

Substrate
The brightening effect is dependent on the nature of the substrate. For example, a very strong reflectance is observed with whitened cotton, but it is weaker in viscose and wool. All synthetic fibres absorb strongly in the near ultraviolet region. Since the fluorescence produced by optical brightening agent is added to reflectance of the substrate, the maximum fluorescence effect is achieved on those substrate whose ability to absorb the ultraviolet region is suppressed by chemical brightening. In the absence of sufficient affinity of brighteners, the application results in yellow to green colour yield.

Saturation
There is a saturation limit for each optical whitening agent. Above certain concentration on the fibre a yellow colour is superimposed on the flourescence resulting in decrease in whiteness. This is because at higher concentration of brighteners a protective optical layer (filter) is formed on the surface of the substrate which prevents the extinction of the molecules of the brightening agent in deeper layers (so called self-quenching, concentration quenching of fluorescence or filter effect).

Method of application
The saturation limit of an optical brightening agent, however, is also dependent on the method of application to the substrate. Usually exhaust application process gives higher whiteness value then it does when applied by padding technique for a given amount of whitener.

Time
Generally optical brightening agents have high rate of exhaustion on the substrate and therefore great care is to be taken to avoid unlevel application. Slow exhaustion rate and increased migration time is necessary to produce level whiteness on the fabric.

Temperature
The optimum temperatures of optical brightening agents on cellulosic fibres are usually between 40 and 60~ and further rise in temperature tend to lower the exhaustion. However, for synthetic fibres higher temperature is needed for good penetration of the brighteners.

pH
The chemical stability, solubility and affinity of optical brightening agents depend on effective pH value in solution. For example, for wool and polyamide fibres, optimum pH is on the acidic side for better exhaustion.

Salt
Generally salt is added in the application bath to promote and also to control the rate of exhaustion of the brighteners on cellulosic fibres.

Automatic Pneumatic Grinding Machine

AUTOMATIC PNEUMATIC GRINDING MACHINE
Selva Kumar
Kalasalingam University, Tamil Nadu, India
Email: selvaddsniper@gmail.com

INTRODUCTION
The pneumatic grinding is a metal grinding machine tool designed to cut/grind metal by applying pneumatic pressure. It is widely used in carding machine to grind wire.

Automatic Pneumatic Grinding Machine

The machine is exclusively intended for mass production and they represent the fastent and more efficient way to cut a metal. The slow speed operation is occurs in a grinding operation. This machine is a multipurpose machine.

Hacksaws are used to cut thin and soft metals. The grinding shaft is used to grinding operation by replacing the hacksaw frame. The operation of the unit is simplified to a few simple operations involving a cylinder block and piston arrangement.

There are numerous types of grinding machines in Engineering field, which are used to fulfil the requirements. We are interested to introduce pneumatic system in especially in grinding machine and also grinding operation.

The main function of Pneumatic grinding is to cut thin and soft metals by pneumatic power.

LITERATURE SURVEY

PNEUMATICS
The word ‘pneuma’ comes from Greek and means breather wind. The word pneumatics is the study of air movement and its phenomena is derived from the word pneuma. Today pneumatics is mainly understood to means the application of air as a working medium in industry especially the driving and controlling of machines and equipment.

Pneumatics has for some considerable time between used for carrying out the simplest mechanical tasks in more recent times has played a more important role in the development of pneumatic technology for automation.

Pneumatic systems operate on a supply of compressed air which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When the pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of the air at intake conditions namely at atmosphere pressure and normal ambient temperature.

The compressibility of the air was first investigated by Robert Boyle in 1962 and that found that the product of pressure and volume of a particular quantity of gas.

The usual written as:

PV = C (or) PıVı = P2V2 

In this equation the pressure is the absolute pressured which for free is about 14.7 Psi and is of courage capable of maintaining a column of mercury, nearly 30 inches high in an ordinary barometer. Any gas can be used in pneumatic system but air is the mostly used system now a days.

SELECTION OF PNEUMATICS
Mechanization is broadly defined as the replacement of manual effort by mechanical power. Pneumatic is an attractive medium for low cost mechanization particularly for sequential (or) repetitive operations. Many factories and plants already have a compressed air system, which is capable of providing the power (or) energy requirements and the control system (although equally pneumatic control systems may be economic and can be advantageously applied to other forms of power).

The main advantage of an all pneumatic system are usually economic and simplicity the latter reducing maintenance to a low level. It can also have out standing advantages in terms of safety.

PRODUCTION OF COMPRESSED AIR
Pneumatic systems operate on a supply of compressed air, which must be made available. In sufficient quantity and at a pressure to suit the capacity of the system. When pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of the air at intake conditions namely at atmosphere pressure and normal ambient temperature. Clean condition of the suction air is one of the factors, which decides the life of a compressor. Warm and moist suction air will result in increased precipitation of condense from the compressed air. Compressor may be classified in two general types.

1. Positive displacement compressor.
2. Turbo compressor

Positive displacement compressors are most frequently employed for compressed air plant and have proved highly successful and supply air for pneumatic control application.

The types of positive compressor

1. Reciprocating type compressor
2. Rotary type compressor

Turbo compressors are employed where large capacity of air required at low discharge pressures. They cannot attain pressure necessary for pneumatic control application unless built in multistage designs and are seldom encountered in pneumatic service.

RECIPROCATING COMPRESSORS
Built for either stationary (or) portable service the reciprocating compressor is by far the most common type. Reciprocating compressors lap be had is sizes from the smallest capacities to deliver more than 500 m³/min. In single stage compressor, the air pressure may be of 6 bar machines discharge of pressure is up to 15 bars. Discharge pressure in the range of 250 bars can be obtained with high pressure reciprocating compressors that of three & four stages.

Single stage and 1200 stage models are particularly suitable for pneumatic applications , with preference going to the two stage design as soon as the discharge pressure exceeds 6 bar , because it in capable of matching the performance of single stage machine at lower costs per driving powers in the range .

COMPONENTS AND DESCRIPTION

PNEUMATIC CONTROL COMPONENT

Pneumatic cylinder
An air cylinder is an operative device in which the state input energy of compressed air i.e. pneumatic power is converted in to mechanical output power, by reducing the pressure of the air to that of the atmosphere.

Single acting cylinder
Single acting cylinder is only capable of performing an operating medium in only one direction. Single acting cylinders equipped with one inlet for the operating air pressure, can be production in several fundamentally different designs.

Single cylinders develop power in one direction only. Therefore no heavy control equipment should be attached to them, which requires to be moved on the piston return stoke single action cylinder requires only about half the air volume consumed by a double acting for one operating cycle.

Double acting cylinders:
A double acting cylinder is employed in control systems with the full pneumatic cushioning and it is essential when the cylinder itself is required to retard heavy messes. This can only be done at the end positions of the piston stock. In all intermediate position a separate externally mounted cushioning derive most be provided with the damping feature.

The normal escape of air is out off by a cushioning piston before the end of the stock is required. As a result the sit in the cushioning chamber is again compressed since it cannot escape but slowly according to the setting made on reverses. The air freely enters the cylinder and the piston stokes in the other direction at full force and velocity.

CONTROL VALVE:
Various types of control valves are used to regulate, control and monitor the air energy for control of direction pressure, flow, etc.

Pneumatic energy is regulated and controlled by pneumatic valves. Functionally valves are divided into four major groups.

• Direction Control
• Flow Control

In our project electrically actuated solenoid operated 5/2 DC valves are used.

Solenoid is another name for an electromagnet. Direction control valves are very often actuated by electromagnets. An electromagnet is a temporary magnet. A magnetic force is developed in an electromagnet when electrical current passes through it and force drops down as soon as it is de energized.

This electromagnet is commonly termed as solenoid. The proper working of a solenoid operated valve depends on the reliability of the electromagnets.

It ensures

• Quick and sure action
• Long life.
• Easy maintenance.
• Less wastage of energy.

Solenoid Valve
The directional valve is one of the important parts of a pneumatic system. Commonly known as DCV, this valve is used to control the direction of air flow in the pneumatic system. The directional valve does this by changing the position of its internal movable parts.

This valve was selected for speedy operation and to reduce the manual effort and also for the modification of the machine into automatic machine by means of using a solenoid valve. A solenoid is an electrical device that converts electrical energy into straight line motion and force. These are also used to operate a mechanical operation which in turn operates the valve mechanism.

Solenoids may be push type or pull type. The push type solenoid is one in which the plunger is pushed when the solenoid is energized electrically. The pull type solenoid is one is which the plunger is pulled when the solenoid is energized.

The name of the parts of the solenoid should be learned so that they can be recognized when called upon to make repairs, to do service work or to install them.

Solenoid Valve

HOUSE AND FITTINGS:
It is provided for the passage of compressed air from the compressor outlet to the operating valve.

Two separate pipes also connect the operating valve with the working cylinder pressure drop through and air line depends on the flow rate, pipe diameter, pipe length and pipe geometry. It can be determined directly for straight pipes of any given length. A small chaining bore size can have marked effect on pressure drop, where as even doubling the pipe length, will only result in doubling the pressure drop.

Pressure drop through bends and fittings can only be determined by empirical tests, since it is specific to the internal geometry involved. Rigid pipes however are less manipulated through remain form of bends with arrangements increase and variable air have to flow and the flow itself may be of fluctuating or pulsating nature. In this case it is thus normally based on practical recommendation.

SEALS:
Seal is an important component of a pneumatic system and is used to prevent the air leakage through the joint.

This project passes the static seal which are used to prevent the leakage through the stationary surface.

Material of the seal is Teflon tape. Teflon has the following properties

• Withstand the system pressure and temperature without any damage.
• Resist the wear and abrasion.
• Recover from deformation.
• Resists the adverse effects such as deterioration and shrinking caused by the system air.

Seals are devices for closing gaps to prevent leakage or make pressure joints and also to prevent the entry of air and dirt from outside into the system. The material of seal must be compatible with the fluid medium. It is a circular ring made of synthetic rubber. It is used for providing tight sealing between the piston and the cylinder wall. It prevents air leakage from the top and bottom of the cylinder.

Seals for air cylinder and valves are not normally called upon to seal pressure higher than about 2 bars. Since the fluid to be seated is a gas, (in our case air) rubbing speeds tends to be high and the seal the seal may have to be operated under dry conditions with minimal lubrication.

CONTROL TIMER CIRCUIT:

Need for a Timer Circuit:
Main purpose to timer circuit is to actuate the solenoid valve at regular interval of time to achieve proper lubrication at the desired interval.

ELECTRONIC CONTROL TIMING UNIT:-
Here the 555 IC has been used as a multi vibrator. The output of IC 555 is fed to the input pin (pin no 14) of CD 4017 continues counting.

The output of the IC becomes available at pin Nos. 3, 2 and 4. The output pulse of any one of output pin triggers (Puts ON) the Triac and current starts flowing across the load connected. This process continues on other pins at different time intervals and the cycle continues. The frequency interval (Time) of the cycle can be adjusted by the pre-set look connected to pin 6 of 555 Timer IC. 

ELECTRONIC CONTROL TIMING UNIT

Automatic Grinding Machine

WORKING PRINCIPLE

PNEUMATIC CIRCUIT:

Pneumatic circuit

Since pneumatic circuit plays a vital role in this device, it is very necessary to explain the working of this circuit.

Initially starting with air compresses, its function is to compress air from a low inlet pressure (usually atmospheric) to a higher pressure level. This is an accomplished by reducing the volume of the air.

Air compressors are generally positive displacement units and are either of the reciprocating piston type or the rotary screw or rotary vane types. The air compressor used here is a typically small sized, two-stage compressor unit. It also consists of a compressed air tank, electric rotor and pulley drive, pressure controls and instruments for quick hook up and use. The compressor is driver by a 10HP motor and designed to operate in 145 – 175 PSI range. If the pressure exceeds the designed pressure of the receiver a release value provided releases the excesses air and thus stays a head of any hazards to take place.

The stored air from compressor is passed through an air fitter where the compressed air is filtered from the fine dust particles. However, before the suction of air into compressor a filter process take place, but not sufficient to operate in the circuit here the filter is used.

Then having a pressure regulator where the desired pressure to the operated is set. Here a variable pressure regulator is adopted.

Through a variety of direction control value are available, a hand operated solenoid Valve with control unit is applied.

The solenoid valve used here is 5 ports, 3 positions. There are two exhaust ports, two outlet ports and one inlet port. In two extreme positions only the directions can be changed while the Centro ore is a neutral position and no physical changes are incurred.

The 2 outlet ports are connected to an actuator (Cylinder). The pneumatic activates is a double acting, single rod cylinder. The cylinder output is coupled to further purpose. The piston end has an air horning effect to prevent sudden thrust at extreme ends.

PRINCIPLES OF WORKING

• The compressed air from the compressor reaches the solenoid valve. The solenoid valve changes the direction of flow according to the signals from the timing device. 

• The compressed air pass through the solenoid valve and it is admitted into the front end of the cylinder block. The air pushes the piston for the grinding stroke. At the end of the grinding stroke air from the solenoid valve reaches the rear end of the cylinder block. The pressure remains the same but the area is less due to the presence of piston rod. This exerts greater pressure on the piston, pushing it at a faster rate thus enabling faster return stroke. 

• The weight attached at the end of the hacksaw frame gives constant loads which lower the hacksaw to enable continuous grinding of the work. 

• The stroke length of the piston can be changed by making suitable adjustment in the timer. 

• Grinding hacksaw frame is removed in the case of grinding operation. The above same procedure is occurring in the grinding operation.

APPLICATIONS

1. Agriculture:

• Crop forming
• Stock breeding
• Animal food industries
• Foresting

2. Utilities:

• Power Station
• Nuclear Engineering
• Water Supply

3. Mining
4. Chemical Industry
5. Plastics and rubber industries
6. Stone, Ceramic and glass industries
7. Metal Industries:

• Iron and Steel
• Non-ferrous metals
• Foundries
• Scrap and recycled metals

8. Leather Industry
9. Textile Industry
10. Paper and Printing Industry
11. Grinding Industries

ADVANTAGES AND LIMITATIONS

ADVANTAGES:

• There is no need of giving feed during every cut due to the presence of weight.
• The grinding/grinding speed can be varied according to our needs by adjusting the timer.
• It is portable
• It does not have any Prime mover, like electric motor related to the unit.
• As the air is freely available, we can utilize the air to cut the metal and hence it is economical.
• Simple in construction than mechanical hacksaw and grinder
• It is a compact one
• Less Maintenance

LIMITATIONS

• Only smaller size and soft metal can be cut
• It is costlier than the mechanical hacksaw because of compressor unit.
• Less efficiency when compressed to mechanical device.
• Leakage of air affects the working of the unit.

COST ESTIMATION

Sl. No.	PARTS	Qty.	Cost
i.	Cylinder block (with piston)	1
ii.	Solenoid valve	1
iii.	Machine vice	1
iv.	Timing device	1
v.	Flexible hoses	-
vi.	Hack Saw frame	1
vii.	Bolts & Nuts	-
viii.	PU Connectors	-
ix.	Flow Control Valve	1
x	Grinding Shaft	1
	TOTAL

 

LABOUR COST
LATHE, DRILLING, WELDING, GRINDING, POWER HACKSAW, GAS GRINDING:
Cost =

OVERHEAD CHARGES
The overhead charges are arrived by “Manufacturing cost”

Manufacturing Cost = Material Cost + Labour cost

Overhead Charges = 20% of the manufacturing cost

TOTAL COST
Total cost = Material Cost + Labour cost + Overhead Charges

Total cost for this project =