FUNDAMENTALS IN SMAW SECONDARY HIGH SCHOOL
- 1. FUNDAMENTALS AND DEVELOPMENTS OF SHIELDED METAL ARC WELDING. SMAW 12 – SECOND SEMESTER
- 2. BASIC FUNDAMENTALS OF WELDING •Welding is the melting, flowing together, and freezing of metals under controlled conditions. •Arc welding uses electricity to heat and melt the metal. •A Weldor is the person doing the welding. •A Welder is the machine doing the welding.
- 3. BASIC FUNDAMENTALS OF WELDING •Shielded metal arc welding is welding where fusion is produced by heating with an arc between a consumable stick electrode and the work piece. •An electrode is a bare metal rod which is usually coated with chemical compounds called flux.The flux coatings burn in the intense heat and form a blanket of smoke and gas that shields the weld puddle from the air.
- 4. BASIC UNDERSTANDING OF ELECTRICAL TERMS IS NECESSARY TO FULLY UNDERSTAND SHIELDED METAL •Electricity is the flow of tiny particles called electrons through a conductor. •Electrons are negatively charged particles. •A conductor allows the flow of electrons. •Voltage is a measure of electrical pressure.
- 5. •When electricity is conducted through a conductor, the movement of the electric energy heats the conductor due to the resistance of the conductor to the flow of electric current through it. •The greater the flow of current through a conductor, the greater the resistance to it, and the greater the heat generated (the higher the amperage setting, the greater the heat produced).
- 6. •When electrical current alternates or reverses the direction of electron flow it is called alternating current (AC). •Electron flow in one direction is called direct current (DC).
- 7. HOW IS METAL PREPARED FOR WELDING? •One of the most important and most often neglected parts of the welding job is preparation of the metal for welding.
- 8. HOW IS METAL PREPARED FOR WELDING? 1. The metal must be free of dirt, grease, rust, paint, or other impurities which may combine with a molten weld bead and cause it to be weakened. Metal should be cleaned by grinding, brushing, filing, or cutting before welding.
- 9. HOW IS METAL PREPARED FOR WELDING? 2. Preparing the correct type of joint for each kind of metal is crucial to securing strong welded structures.
- 10. PROCEDURES AND TECHNIQUES FOR SHIELDED METAL ARC WELDING •Good welds can be attributed to correct selection and manipulation of the electrode and welding current.
- 11. THE FOLLOWING SKILLS MUST BE PERFORMED IN UNISON TO ACHIEVE A WELD OF ACCEPTABLE QUALITY. •The proper amperage setting for any welding job is necessary to get good penetration with minimum spatter. Correct amperage can be identified somewhat by sound.
- 12. THE FOLLOWING SKILLS MUST BE PERFORMED IN UNISON TO ACHIEVE A WELD OF ACCEPTABLE QUALITY. •When the amperage is correct, a sharp crackling sound can be heard. •A humming sound will indicate too low an amperage setting and the deposited electrode will pile up, leaving a narrow, high bead that has poor penetration and little strength.
- 13. THE FOLLOWING SKILLS MUST BE PERFORMED IN UNISON TO ACHIEVE A WELD OF ACCEPTABLE QUALITY. •Correct amp setting depends on the thickness of the base metal and the diameter of the electrode. •Learning to maintain the correct arc length for the electrode you are using is necessary in order to be successful.
- 14. THE FOLLOWING SKILLS MUST BE PERFORMED IN UNISON TO ACHIEVE A WELD OF ACCEPTABLE QUALITY. •The correct angle of the electrode will depend on the type of weld that is to be completed. Hold the electrode at a 90 degree angle to the work as viewed from the end of the two plates being joined, and 5 to 15 degrees in the direction of travel.
- 15. THE FOLLOWING SKILLS MUST BE PERFORMED IN UNISON TO ACHIEVE A WELD OF ACCEPTABLE QUALITY. •Correct speed of travel affects the amount of electrode deposited and the uniformity of the bead. It should produce a bead that is 1.5 to 2 times the diameter of the bare end of the electrode.
- 16. FOLLOWING PROPER PROCEDURES WHEN PREPARING TO WELD AND STRIKING THE ARC WILL DEVELOP CONFIDENCE IN YOUR ABILITIES. 1. Prepare the work area so that everything is ready and convenient before you start. 2.Make a final check to see that flammable materials are out of the way and that unnecessary tools are not lying around.
- 17. 3. Be sure the machine is turned off. 4. Set the machine to the desired amperage 5. Insert the bare end of the electrode in the electrode holder and hold the end of the electrode about 1 inch above the metal at the point where the weld is to be started.
- 18. 6. Turn the welder on. 7. Lower the helmet over your eyes, bring the electrode in contact with the work and withdraw it slightly.
- 19. 8. There are two methods used in starting the arc. •A striking movement is similar to striking a match. •A tapping movement is where the electrode is quickly tapped on the surface of the metal to prevent it from sticking to the base metal.
- 20. WRITTEN ACTIVITY #4 What are the proper procedures when preparing to weld and striking the arc will develop confidence in your abilities?
Editor's Notes
- #2: Weldor - A person who welds, or operates a welding machine
- #5: Polarity is when an entity contains two distinct and opposite poles that can either attract or repel each other.
- #9: Different types of joints
- #13: Arc length is the distance from the tip of the bare end of the electrode to the base metal.
- #14: Arc length is the distance from the tip of the bare end of the electrode to the base metal.
- #15: Arc length is the distance from the tip of the bare end of the electrode to the base metal.