Thursday, 9 August 2012

A Report On Wire Wound Resistor Manufacturing




Prepared By:

                                        Vikas Sakre (PGDIE 42 Roll No-103)


INTRODUCTION

Resistor is a passive electronic component having resistivity and is used for various applications in any electronic equipment as a part of electronic circuit used in it. Resistors offer resistance to flow of current. Resistor can be broadly classified into fixed resistor and variable resistor. Again fixed resistor is grouped into carbon composition, metal composition, oxide coated and wire wound resistors. Resistors are characterised by resistance value, power rating (in watts) and tolerance.
Wire wound Resistors consist of a cylindrical core which is wrapped or wound with wire. The cylindrical core is typically made from a ceramic material. The wire is a type of resistance wire. Wire wound resistors are a type of power resistor and are very accurate. Wire wound resistors are available as fixed, or adjustable to be used as a rheostat or potentiometer.
Wire wound resistors, which are used in electronic equipments and instruments where high precision and more power dissipation are specified. Wire Wound Resistors are preferred over metal oxide resistors because of being better temperature co-efficient and of smaller size. Again wire wound resistors can be divided into silicon coated ceramic type, aluminium type etc., based on chemical composition and type of application. Silicon coated resistor is further divided into radial, axial, commercial type, fusible etc., depending on the application. Wire Wound Resistor finds application in power equipments, testing and measuring equipments, communication equipments, medical electronic equipments, computer hardware, audio and video equipments, Defence and Space applications.

Typical application for wirewound resistors includes device requiring high current handling capability, heat dissipation and resistance stability and accuracy.


MARKET POTENTIAL

As mentioned earlier, Wire Wound Resistor finds applications in all electronic equipments consisting of electronic circuits. They are widely used in process control instruments, telecommunication equipments, testing and measuring instruments, power equipments etc., for various functions like current limiting, on load, overload, protection etc.

There are many units in the country manufacturing different types of Wire Wound Resistors. Most of them are manufacturing silicon coated, ceramic encased and aluminium wound resistors. But there is an incremental growth of electronic industries in the country, which has created further scope of new industries in the field of wire wound resistors.

The new entrepreneur should have knowledge and should collect data about various types of wire wound resistors used by the electronic industry and its different applications. Manufacturing Wire Wound Resistors with high precision, better tolerance will increase the market share.

Conventional plant and machinery is indigenously available. Automatic machinery can be imported. Some of the raw materials have to be imported.


MACHINES & MATERIAL HANDLING EQIPMENTS REQUIRED

¢  Toggle Action Press ½ Ton Cap.
¢   Automatic Coil Winding Machine
¢   Lead cutting Machine Grinder
¢   Lead Straightening machine
¢   Lead Tinning machine
¢   Spot Welding machine
¢   Oven (Temp. controlled)
¢   Stirrer (Ball Mills)
¢   LCR - Q Meter
¢   Digital Temperature Indicator 4½ Digit Bench Micro ohm Meter
¢   Dimmer Stat (4A)
¢   4 ½ Digit Digital  Multimeter
¢   Load Tester and Brake Tester
¢   Fusing Tent Machine
¢  Tension Tester
¢  Marking Machine  with accessories
¢  Resistance oil  standards
¢  Electrification
¢  Office Equipment Furniture
¢  Jigs/Fixtures


MANUFACTURING PROCESS

Process of Manufacture

The porcelain pipes of the required sizes are obtained and cleaned. The brass/ nickel silver clamps are fixed on the ends. The nichrome or other resistance wire of required gauge is then wound on these porcelain pipes. The resistance is then tested to the required specifications. The ends of the resistance wire are soldered with the clamps on both ends of the porcelain pipes. Then the resistance is given a coating of vitreous enamel and baked in a furnace. The coating process is repeated two or three times for perfect insulation. Finally they are tested according to the specifications.

 


For ceramic encased type resistor (power resistor), the resistors are manufactured by winding resistance wire on ceramic rods. Then ends are spot welded to ceramic caps with leads on lugs followed by dipping in silicon based resin and drying. These resistors are tented at high temperature and high power dissipation as per the specification before packing and despatch.

The essential production machinery and test equipment required for the project have been indicated. The unit may also utilize common test facilities available at Electronics Test and Development Centres (ETDCs) and Electronic Regional Test Laboratories (ERTLs) set up by the State Governments and STQC Directorate of the Department of Information Technology, Ministry of Communication and Information Technology, to manufacture products conforming to BIS standards

Resistors with wire lead for through-hole mounting
Through-hole components typically have leads leaving the body axially. Others have leads coming off their body radially instead of parallel to the resistor axis. Other components may be SMT (surface mount technology) while high power resistors may have one of their leads designed into the heat sink.

IMPLEMENTATION SCHEDULE
The major activities in the implementation of the project have been listed and the average time for implementation of the project is estimated at 12 months.

S.No
NAME  OF ACTIVITY
PERIOD IN MONTHS                  
     (ESTIMATED)
1
Preparation of project report
1
2
Registration and other formalities
1
3
Sanction of loan by financial institutions
3
4
Plant and Machinery

     a
Placement of orders
1
     b
Procurement
2
     c
Power connection/
Electrification
2
     d
Installation/Erection of machinery/Test Equipment
2
5
Procurement of raw materials
2
6
Recruitment of Technical, personnel etc.
2
7
Trial production
11
8
Commercial production
12

Quality Control and Standards

Standards

Since performance of electric equipments depends on the quality of component used, it is very essential that quality standards are followed. The samples can be tested as per Indian Standards.



General Specification
Vitreous enamel/
             Ceramic coated

Silicon coated wire
             resistors


wound  resistors





Range : 0.1 Ohm to
 Range : 0.025       Ohm to

100 K Ohm
100 K Ohm

Power Ratio: 1 to 200Watts
Power rating: 1 to 20 watts

Tolerance: above
Tolerance: 5%

1 Ohm + 1%
and 10%

1 Ohm + 5%


below 1 Ohm + 10%


Temp. co-efficient:
Temp.co-efficient:

100 PPM to 200 PPM
200 PPM/deg. C


To 1500 PPM/deg.C




Additional Information


a) The Project Profile may be modified/tailored to suit the individual entrepreneurship       
qualities/capacity, production programme and also to suit the locational,                                 characteristics, wherever applicable.

(b) The Electronics Technology is undergoing rapid strides of change and there is need for regular monitoring of the national and international technology scenario.
    The unit may, therefore, keep abreast with the new technologies in order to keep them in pace with the developments for global competition.

(c) Quality today is not only confined to the product or service alone. It also extends to the process and environment in which they are generated. The ISO 9000 defines standards for Quality Management Systems and ISO 14001 defines standards for Environmental Management System for acceptability at international level. The unit may therefore adopt these standards for global competition.

(d) The margin money recommended is 25% of the working capital requirement at an average. However, the percentage of margin money may vary as per bank’s discretion.
Pollution Control

The Govt. accords utmost importance to control environmental pollution. The small-scale entrepreneurs should have an environmental friendly attitude and adopt pollution control measures by process modification and technology substitution. Awareness among the staff members of the industrial undertaking should also be created for abatement of pollution.

India having acceded to the Montreal Protocol in Sept. 1992, it has become mandatory for India to phase out the production and use of Ozone Depleting Substances (ODS) like Chlorofluoro Carbon (CFC), Carbon Tetrachloride, Halons and Methyl Chloroform etc. These chemicals/solvents are to be phased out immediately with alternative chemicals/solvents.
Government of India has already taken a number of policy measures, both fiscal and legislative, to encourage early adoption of non-ODS technologies. A notification for detailed Rules to regulate ODS phase out under the Environment Protection Act, 1986 have been put in place with effect from 19th July 2000. The Rules give the necessary legal backing and time frame for the phase out of ODS.
                                          
We are at the very critical stage where the momentum generated in the past has to further strengthen. As such the following steps may help to control pollution in electronics industry wherever applicable

i)       In electronic industry fumes and gases are released during hand soldering / wave soldering/Dip soldering, which are harmful to people as well as environment and the end products. Alternate technologies may be used to phase out the existing polluting technologies. Numerous new fluxes have been developed containing 2-10% solids as opposed to the traditional 15-35% solids.

ii)      Electronic industry uses CFC, Carbon Tetrachloride and Methyl Chloroform for cleaning of printed circuit boards after assembly to remove flux residues left after soldering, and various kinds of foams for packaging.

Many alternative solvents could replace CFC-113 and Methyl Chloroform in electronics cleaning. Other Chlorinated solvents such as Trichloroethylene, Perchloroethylene and Methylene Chloride have been used as effective cleaners in electronics industry for many years. Other organic solvents such as Ketones and Alcohols are effective in removing both solder fluxes and many polar contaminants


Energy Conservation


With the growing energy need and shortage coupled with rising energy cost, a greater thrust in energy efficiency in industrial sector has been given by the Govt. of India since 1980s. The Energy Conservation Act, 2001 has been enacted on 18th August 2001, which provide for efficient use of energy, its conservation and capacity building of Bureau of Energy Efficiency created under the Act.

     The following steps may help for conservation of electrical energy:

i)       Adoption of energy conserving technologies, production aids and testing facilities.

ii)      Efficient management of process/ manufacturing machineries and systems, QC and testing equipments for yielding maximum Energy Conservation.

iii)    Optimum use of electrical energy for heating during soldering process can be obtained by using efficient temperature controlled soldering and de-soldering stations.

iv)    Periodical maintenance of motors etc.

Use of power factor correction capacitors. Proper selection and layout of lighting system; timely switching on-off of the lights; use of compact fluorescent lamps wherever possible etc.

References:

1) dcmsme.gov.in/publications/pmryprof
2) wikipedia.com
3) www.hotfrog.in/Products/Resistor 
4) www.pridmore.com/OHMITE 









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