ARC WELDING
LEARNING OUT COMES
At the end of this lab work, student able to:
• Understand of arc welding in joining process such as make a T-joint.
• Know the problem that occurs on the arc welding process.
• Type of metal and electrode that are used in arc welding.
• Know the angles that are used in arc welding process.
INTRODUCTION
The principle of arc welding is to attach a ground cable to the work piece .The machine was set to the correct amperage base on the thickness of the material.fit the electrode in the electrode holder and with the head shield down the strike the rod against the work to start a flow of current .That procedure intense heat and light and your seam together. Welding thicker work piece requires more heat in the form of higher amperage from the machine.
TOOL AND EQUIPMENT
1) Ac/Dc or combination of Ac/Dc machine. 2) Glove. 3) Wire brush. 4) Chipping hammer 5) Apron. 6) Head shield. 7) Electrode holder. 8) Pieces of metal.
SAFETY AND HEALTH
1) Wear safety equipment such as head shield, glove and apron before start welding. 2) Don’t watch the ultraviolet rays spatters when welding using eye without a head Shield.
3) Carry Out at a comfortable area and where the is good welding will be done away from the flammable materials.
4) Do not disturbed other student that are still work.
THEORY
The basic principal of arc welding involves heating or melting of the base metal using electric arc. The electric arc is formed when there is a voltage difference between the metal coating at the end of the electrode and the surface of the metal. The Arc will produce enough to the melt the base metal and the end of the electrode to form a pool of molten metal. In this semester, T-joint is commonly found when joining two plates where one plate is perpendicular to other. The electrode should be at 45° between two parts. So that, that equal heat and filler metal is directed onto both process.
PROCEDURE
1. Clean the surface of the metal plate with wire brush before welding. Place as close to the weld as possible to the metal plate
2. Before striking an arc, insert an electrode to the electrode holder.
3. Adjust the electric current according to the electrode size I use 100V.Arc length between the plate n electrode is 1/16 and 3/32 in diameter --- 1/16 in (1.6 mm). 4. Weld along the base from left to right.
5. Positioning electrode holder – hold the electrode nearly perpendicular to the work,. although tilting it ahead
CONLUSION
At the end of this experiment:
• There are problem occurs on the arc welding process.
• To get a best result of this arc welding process, student must know the angle that are used, concentration, and the movement of the electrode and speed of moving the electrode.
• The thickness of the metal and type of the electrode are used are the factor in arc welding process.
GAS WELDING
LEARNING OUTCOMES
At the end of this experiment, student should know:
• How to using oxyacetylene gas in cutting and brazing process.
• Type of torch that are used
• Thickness of the metal that involved in cutting and brazing process.
• Angle that are used in cutting and brazing process.
INTRODUCTION
Oxyfuel gas welding or commonly know as gas welding use flame as source of heat. The flame is produced from mixture of fuel gas and pour oxygen the flame melts the edges or surfaces of the joining metals. This allow the molten metal to flow together and form a solid continuous joint upon cooling
Welding methods or processes which fall under oxyfuel gas welding group are oxyacetylene welding(OAW), oxyhydrogen welding(OHW),pressure gas welding(PGW)and air acetylene welding(AAW).
TOOLS AND EQUIPMENTS
1. Oxygen and acetylene gas cylinders for combustion. 2. Pressure regulator to adjust and stabilize the gas pressure.
3. Two-way valve to control the one way flow of oxygen and acetylene gas. 4. Gas hose to channel the gas from the cylinder to the torch.
5. Special key to lock or unlock the oxygen and acetylene gas cylinder valve. 6. Spark lighter to ignite the welding torch.
7. Cutting torch.
8. Some pieces of metal. 9. Filler rod. 10. Fluxs. 11. Wire brush. 12. Goggle. 13. Glove.
SAFETY AND HEALTH
1) Wear a face shield / safety glasses at all times. 2) Obtain permission before use.
3) Store separately -> Oxygen and Acetylene cylinders.
4) Chained Securely -> Equipment connected to compressed gas cylinders. 5) Store cylinders outdoors in a well ventilated area.
6) Keep caps on any cylinders not having regulators attached to them.
7) Follow specific procedures for turning systems on and off (ten steps listed above). 8) Never expose equipment to oil or grease -> Spontaneous fire possibility.
9) Always wear leather gloves and an apron.
10) Learn to recognize the odors of combustible fuels.
11) Protect gas cylinder storage areas: Lock in a chain link fence. 12) In case other equipment catches fire, turn off the gas in the tank.
13) Keep all equipment or cylinders that can discharge gas pointed away from everyone and clothing.
14) Never leave clothing where it can be saturated with oxygen or fuel gasses. a 15) When connections are opened or cylinders changed, check thoroughly for leaks. 16) Work only in areas that are free from materials that will burn.
17) Do not bump or put pressure on equipment connected to compressed gas cylinders.
18) Never work in an area without a fire extinguisher. 19) Never move a cylinder without a cap.
OXYACETYLENE CUTTING
THEORY
Oxyacetylene cutting process is use to cut metal. The melting of metal during pre heated is importing during the cutting, but the most important is the oxidation metal process during metal heated until it color become red, release pour oxygen on it, this chemical reacting called oxidation process.
OXYACETYLENE CUTTING PROCEDURE 1. Make sure work area is clean and tidy.
2. Prepare the metal that you want to cut on the table.
3. Determine the size the cutting torch that suitable with the thickness of the metal. 4. Make a line on the surface the metal with chock, Scriber at the place that you
want to cut.
5. Spark the torch and start the cutting at 90° on the base metal.
6. Start the cutting from the corner. Make pre-heated on the metal until it like red. After that released the pour oxygen to cut the metal.
BRAZING
THEORY
Brazing is a process that didn’t melt the metal. Brazing is joined two metal that different type, where the metal heated high than 800F (427°C).Filler rod is added on the surface of metal to make the easy to added filler rod put some flux on it tip.
BRAZING PROCEDURE
1. Clean the metal from grease, oil or anything that useless on the surface of metal. 2. Joint two of metal with pengapit to make it closes.
3. Choose the flux that suitable for joining the metal. 4. Put some flux o the surface of metal.
5. Heats the metal on braze temperature, after that add the filler rod on the butt surface of two metal.
6. Stop heat the metal when braze alloy close the surface joined. Do not make over heated because it can make the ionic bond of the metal become weak.
7. Lastly, brush the metal to see it joint.
CONLUSION
At the end of this experiment, students know:
• The problem that occurs on the metal (in cutting process and brazing process.)
• Type of torch are used in gas welding (cutting and brazing)
• Angle that are used in this gas welding.
• How to get the best heat of the cutting process
• Factor that involved in this gas welding( cutting and brazing)
REFFERENCE
