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 _________________________________________________________________________________________. 60XX = Tensile Strength in pounds (X 1,000) 60,000 lbs per square inch XX1X = Welding Position 1 =All 2 = Flat and Horizontal 3 = Flat XXX1 = Polarity 1,3,4,8=AC or DC Reverse 2 = AC or DC straight 0 = DC Reverse

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 12-14 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.