AGRICULTURAL MECHANICS I UNIT I:METAL SKILLS COMPETENCY:AM26.00 Research arc welding equipment. OBJECTIVE:AM26.01 Compare types of arc welding machines, welding equipment, and electrodes.

Welding A process of fusing metal together using heat.

A. Types of Welding Machines 1. AC (alternating current) used for most agricultural arc welding jobs and has low purchase cost compared to other arc welders. 2. DC (direct current) are generator operated and can be used where regular electrical power is not available.

Types of Welding Machines 3. AC/DC welders use a rectifier to change regular AC current to DC. These welders can be used as either AC or DC.

Types of Welding Processes SMAW – Shielded Metal Arc Welding GMAW – Gas Metal Arc Welding GTAW – Gas Tungsten Arc Welding

TIG Welder 4. TIG (tungsten inert gas) welders have an electric power unit, a pressure reducing regulator, electrode holder, tungsten electrode, nozzle, cables and hoses, and a gas supply unit. The two gases used are helium and argon.

TIG The tungsten electrode is not consumed (burned) and there is no slag on the bead. TIG is good for welding stainless steel and aluminum because it is stronger and more free of corrosion than other welders.

Types Of Welders 5. MIG (metallic inert gas) welders are wire feed welders that use a consumable wire fed automatically through the torch and can be used in industries as an automatic welder.

Welding Equipment 1. Helmet, leather gloves, leather aprons, leather welding jacket, and leather boots are for protection. 2. Chipping hammer removes slag, and wire brush removes rust and dirt. 3. Clamps and vise grip clamps are used to hold metal in place for welding.

C. Electrodes Electrodes are wire cores or rods usually covered in flux. 1. Size is the diameter of the metal rod not including flux. 2. Classification code system has a letter and four numbers such as E6011 or E6013.

Electrodes 3. E6011 is the most commonly used electrode for welding for welding farm projects because it can be used for all-purpose welding of mild steel, has deep penetration, and can be used with both AC and DC welders. 4. E6013 is a good general- purpose electrode but only has medium penetration.

Uses D. A shade 10 lens in a welding helmet protects the eyes of the person welding or the person watching someone weld Never use less than 10 shade

Basic Arc Welding Procedures A. Metal should be cleaned before it is welded. A grinder is the fastest way, but a wire brush or other methods may be used to remove paint, rust, dirt, oil, etc. B. Metal more than ¼" thick should be beveled at a 30 degree angle and placed 1/16" to 1/8" apart before two pieces are welded together.

C. Types of Weld Joints 1. Butt – two pieces of metal lying in the same plane such as end- to-end or edge-to-edge in flat position. 2. T or “T” two pieces of metal placed together to form a T or a  or ┤, two pieces at a 90° angle to each other. A fillet weld is used to fuse the two pieces permanently.

Types of Weld Joints 3. Lap – two pieces of metal overlap each other. 4. Corner – two pieces of metal make a 90° corner. 5. Edge – two pieces placed parallel to one another or stacked on top of each other.

Correct Amperage D. Welding position, metal thickness, and electrode size are used to determine amperage setting.

Amperage setting 1. Amperage too low causes a narrow, high bead with poor penetration. 2. Amperage too high causes a flat bead with excessive spatter. 3. Correct amperage helps make a uniform bead with bead width and penetration depth equal to each other.

Welding Procedures A. Before metal is welded, it should be identified, cleaned and cut to correct size (if needed). B. If an electrode sticks to the metal, the electrode should be wiggled back and forth, or it should be released from the electrode holder.

Welding Procedures E. Tapping or scratching methods can be used to strike an arc (starts a weld). Bump start Scratch start

Welding Procedures F. Arc length should be the same as the diameter of electrode. G. Many different electrode movements or weaves are used to make a bead. They must be uniform. Zig-Zig motion is preferred.

Temperature Welders heat metal to a temperature of 9000 degrees F. if needed. Amp ranges are from amps.

Duty Cycle Percentage of time a welder can operate without overheating Number of minutes out of 60 that a welder can operate at full capacity. Example: 30% would be 18 minutes in a hour. 50% would be 30 minutes.

Polarity - DCEN Straight-direction of electrical flow such that the work is positive(+) and the electrode is negative(-).

Polarity - DCEP Reverse - Direction of electrical flow such that the work is negative (-) and the electrode is positive (+)

Welding Equipment Chipping Hammer Welding Table Wire Brush Helmet - Hand Shield Gloves

Terms Bead - deposit left after a weld Crater- depression left at the end of a weld where the rod contact ends. Weaving - movement of the welding rod. Puddle - pool of hot liquid metal at the point of contact between the base metal and the electrode.

Flux - chemical compound on a welding electrode that cleans the metal and forms a gas cloud over the weld Tack Weld - small weld designed to hold the metal in place until a stronger weld can be made.

ARC Arc - Light formed as the electricity jumps across the gap between the electrode and the base metal. Arc gap is distance between metal and electrode. Should be same as diameter of electrode.

An Arc produces two things Extreme heat up to 9000 degrees Ultra-violet light which can burn the skin and eyes.

Welding Positions 1. Flat 1. easiest 2. Horizontal 3. Vertical 4. Overhead 1. hardest