Arc Welding By John Templeton Objectives Identify and

Arc Welding By: John Templeton

Objectives • Identify and explain safety practices and procedures as related to electric and oxy-fuel welding • Identify equipment used in SMAW welding • Explain the SMAW process • Identify the 2 types of welding current and machines

Arc Welding • The process of ___________________________________________. • Otherwise known as SMAW (shielded metal arc welding) – The electrode produces a gas which shields the arc from the atmosphere as the electrode melts.

SMAW Advantages • Scrap metal can used make repairs • ______________________ • Metal repair and construction can be accomplished more economically • Arc welders can be used to accomplish jobs like cutting, piercing, gouging and beveling

Welding Equipment • • • _________ Welding gloves Electrodes Welding machine Chipping hammer _________

Welding Equipment • Welding leads • _________ • Ground clamp

Alternating Current Welding • AC (alternating current) – Most common – ____________________ – Can handle most agriculture and construction jobs – Alternating flow of electrons

SMAW

Direct Current Welding • DC (direct current) – Can produce direct current of both straight (negative) and reverse (positive) polarity. – _____________________. – Makes a continuous flow of electrons

Straight/Reverse Polarity • Straight Polarity (DC-) – Work is positive and electrode is negative – ____________ – Shallow penetration • Reverse Polarity (DC+) – Work is negative and electrode is positive – Used to weld thicker metals – Deeper penetration

Types of Welding Machines • AC machine – __________

Types of Welding Machines • AC/DC – _____________________ • Alternating • Direct current + (reverse polarity) • Direct current – (straight polarity) • This machine will have a rectifier switch which will allow it to switch between the three • Or the leads will need to be placed in certain parts of the machine.

Types of Welding Machines • AC/DC Machines – ____________________ – Are the most popular. – Allow the operator to weld metal of all thickness.

Types of Welding Machines • ___________________ ______

Duty Cycle • Tells the operator how long his machine can operate without causing damage to the machine. • ______________________________________.

Duty Cycle • If a machine has a duty cycle of 25%, for every ten minutes the machine is operated you can only weld for 2. 5 minutes. • ___________________.

Electrodes • All major manufacturers of welding electrodes use the American Welding Society (AWS) code of specifications. • ___________________.

Electrodes • Electrodes are classified according to type of coating, composition of the weld metal and operating characteristics. • ______________________________________ ___________

Electrodes • _________________________. • 60 XX = Tensile Strength in pounds (X 1, 000) • 60, 000 lbs per square inch • XX 1 X = Welding Position • 1 =All 2 = Flat and Horizontal • XXX 1 = Polarity • 1, 3, 4, 8=AC or DC Reverse • 2 = AC or DC straight • 0 = DC Reverse 3 = Flat

Electrodes • What is the classification of an E 7018? –E – 70 – 1 – 8

Electrode Diameter • Electrodes are also measured by their diameter (the diameter of the electrode without including the flux. • ______________________. • Always use an electrode ½ the size of you base metal – What does this mean?

Electrodes • What diameter electrode should you use if your base metal is ½ in thick? • 1/8 inch? • ¼ inch?

Electrodes • ___________________: – How thick is your base metal? – What condition is your metal in? – What type of machine do you have access to? – Welding position?

Welding Safety • Electrical shock – __________________. – Make sure the cables are not cut or frayed. – Do not stand in wet surfaces. – Wear leather gloves. – Wear rubber-soled shoes

Radiant Energy • Radiant Energy can cause burn – Make sure you helmet is in good repair and lenses are not cracked. – _____________________ – Say cover before welding, so that everyone can protect themselves from radiant energy

Eye Protection • Make sure you are welding with a shade of 1214 lens • ___________________.

Ventilation • Make sure you are welding in a well ventilated area • If you become sick do not continue and drink milk. • __________

General Safety • ___________________. – Welding leads – Flammables – Cover eyes while chipping slag

What to do and what not to do

Review • What are the types of welding current? • What are the types of welding machines? • Describe proper ventilation when welding.