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    TITLE : Welding Operation

    OBJECTIVE : To demonstrate welding process to join two pieces

    INTRODUCTION :

    Welding is a fabrication process that joints two or more materials

    together, usually metals or thermoplastics. This is often done by

    melting the works pieces and adding a filter material to form a pool of

    molten material that cools to become a strong joint. Many different

    energy sources can be used for welding, including a gas frame, an

    electric arc, a lase, an electron beam, friction, ultrasound.

    Shielded metal arc welding (SMAW) is one of the most common types

    of arc welding as shown in Figure B. Its electric current is used to strikean arc between the base material and consumable electrode rod,

    which is made of steel and covered with flux that protects the weld

    area form oxidation and contamination by producing CO2 gas during

    the welding processes.

    Figure A: Shielded metal arc welding (SMAW)

    TOOLS REQUIRED : Welding Machine

    OPERATION REQUIRED : i. Weldingii. Finishing

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    APPARATUS :

    1. Gloves

    2. Two 4inch(10cm) Metal plates

    3. Electrodes

    4. Electrode holder

    5. Head Shield

    EXPERIMENTAL PROCEDURE :

    1. Gloves and screen are worn.

    2. Both of the metal plates are made same parallel to

    get proper butt position. Place some metal holders

    on the base of two metals , so it wont move while

    welding.

    3. Long sleeve jackets and gloves are worn. Welding helmets are

    prepared with dark face plates and make sure its plastic screen is

    clear to see through.

    4. First warm the electrode by sliding on to any metal sheet, if the

    electrode is hot enough then continue to welding.

    5. Welding is started gently in the directional fashion from one end.

    Then, Weld on another side reversely.

    6. Chipped out the oxidized layer and cleaned with a wire brush after

    completing the weld.

    7. Tools are returned and machine is cleaned after operation.

    RESULT & DISCUSSION :

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    Figure C: Good welding

    Figure D: Failed Welding

    SAFETY AND HEALTH:

    1) Wear safety equipment such as head shield, gloves and apron

    before start welding.2) Do not watch the ultraviolet rays spatters when welding using

    eye without a head shield.

    3) Carry at a comfortable area and where the welding will be

    done away from the flammable materials.

    4) Do not disturb other students that are still working.

    5) After finish work, use a wet towel to cover eyes.

    CONCLUSION :

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    In this welding operation results, we do a comparison with the

    good welding and failed welding. So that, we can find out any

    discrepancy and sources of error of the experiment.

    Discrepancy:

    1. Figure B has a good weld on a metal plate and keeps it

    joined strong and Figure C has bad weld on a metal plates it

    would be separated quickly with a very less force .

    Sources of error:

    1. Most of the welding processes involve heat. High temperature

    heat is largely

    responsible for welding distortion and stresses.

    2. When metal is heated it expands, and it expands in all

    directions.3. Welding-distortion or deformation or warping of weldmends

    during welding is a natural outcome of intrinsic non-uniform

    heating and cooling of the joint.

    4. Distortion is the result of the action of internal stresses which

    are produced while welding, and remain in the part after

    heating is removed, as briefly explained in the following.

    At the end of this experiment, there are problem occurs on the

    welding process. To get a best result of this welding process, student

    must know the angle that are used, concentration, and the movement

    of the electrode and speed of moving the electrode.

    REFERENCES :

    i. Larry Jeffus 1983, Welding Principles and Application, 5th Edition,

    Thomson Learning, Inc, USA.

    ii. B. H. Amstead, Philip F. Ostwald, Myron Louis Begeman 1987,

    Manufacturing Processes, 8th Edition, John Wiley & Sons Inc, USA.iii. http://www1.gantep.edu.tr/~oyilmaz/Lecture%20Notes/ME%20473/Design

    %20of%20Weld%20Joints%20and%20Welding%20Errors.pdf

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