Introduction to Welding Area: Ag Mechanics Unit: Arc Welding

OAW Oxyacetylene Tank of Oxygen Tank of Acetylene Striker Goggles

GMAW Gas Metal Arc Tank of C25 (Oxygen/ Argon Mix) Mig Gun

SMAW Shielded Metal Arc Electrode

GTAW Gas Tungsten Arc Rods / Spool Gun (filler Metal) Pedal Non Consumable Electrode Aluminum / Softer Metals

OAC Oxyacetylene cutting Cutting Attachment Different O2 & Acet. Settings Striker Goggles

PAC Plasma Arc Cutting Air Supply Cutting Torch Clamp

Objectives: To identify approved clothing for Arc Welding To determine the proper safety equipment needed for Arc Welding. To identify the parts of an Arc Welder. To identify how an Arc Welder works.

Behavior Most accidents are caused by carelessness Caused by human error Refrain from getting involved in poor shop behavior: scuffling playing with tools tripping running pushing hurrying projects disobeying shop rules loud talking

What are the approved safety clothing and gear for Arc Welding? Do not wear clothes that you do not want to get dirty. Body Protection Tight woven cotton or denim fabrics are most common and inexpensive. Leather is the most effective but is more expensive. Foot Protection Leather shoes that cover the entire foot and have a high top.

Approved safety clothing and gear cont’ Hand Protection Gauntlet type leather gloves that are heavy enough to protect hands from the heat. Welding Helmet Most made of lightweight, heat resistant materials Protection for the head and face Welding Lens Fitted to the helmet At least a # 10 shade Safety Glasses MUST be worn at all times

Here’s a good example of a welder wearing all the proper welding protection

SAFETY: Eye Protection “An ounce of prevention is worth a pound of cure” when it comes to eye protection Always wear proper eye protection when working in the shop A welder must be protected from harmful light radiation given off by the welding process For welding you will be using chipping goggles and a welding helmet

Here are examples of proper eye protection

What are some safety practices used in Arc Welding? Safety First Always check equipment for warn or damaged parts Make sure all safety gear is on and in proper working order. WEAR YOUR SAFETY GALSSES!!!

Safety practices cont’ Good Ventilation Welding fumes can be harmful to the welder causing implications such as: Irritation of the respiratory tract Metal fume fever A condition known as siderosis Slightly increase the risk of lung cancer For these reasons, one should take precaution with welding fumes

Welding Fumes Welding should be done in a well ventilated area Should attempt to control fumes at the source Common ways Extracted benches Local exhaust ventilation

Common Ventilation Practices Extracted bench method Local exhaust ventilation

What are some ways to prevent/protect ourselves from fire? Discard frayed cords and wires Don’t wear auto clothes in the welding shop Keep flammable liquids away from heat Class C fire extinguishers for electrical and chemical fires Fire Blanket Use on people before trying to use a fire extinguishers.

Examples of Welding Practices

What is Arc Welding? Arc Welding is the process of fusing metal together using the heat of an electric arc. Done by sending an electric current through a coated metal rod called an electrode Creates temperatures greater than 90000 F.

What are the common terms used in Arc Welding? Arc Welder Machine that supplies power for the welding process Electrode Metal rod with a flux coating that carries the current to the base metal Base Metal The metal to be welded on Arc Length Distance from electrode to the base metal

Common terms cont’ Voltage Amperage Resistance Open Circuit Voltage Measure of the electrical pressure. Amperage Measure of the electrical current flowing through a circuit. Resistance The opposite to the flow of current which converts energy into heat. Open Circuit Voltage Constant amount of current flowing between electrode and base metal

What are the parts of a SMAW welder? The power supply unit. 2 types Alternating Current (AC) and Direct Current (DC) Cables 2 cables the electrode (+) and the grounding (-) that carry the electrical current

Parts of a welder cont’ Electrode Holder Grounding clamp Spring loaded clamp with insulated handles attached to the electrode cable. Holds the electrode. Grounding clamp Spring loaded clamp attached to the grounding cable. Attaches to the welding table or project to carry the current back to the welder.

How does electricity flow in a welder? Positive Cable Electricity flows from the POSITIVE cable holding the electrode, to the Base Metal and through the grounding clamp back through the NEGATIVE cable to the machine Electrode Base Metal Negative Cable

AC vs. DC Current

Parts of the SMAW Welder

Parts of a GMAW Welder

A B C D E F Welding current too low. Welding current too high. Arc too long. Welding speed too fast. Welding speed too slow. Proper amperage, voltage, and speed.

Parts of OAW

Oxygen Colorless Odorless Promotes combustion (Not a flammable gas)

Acetylene Colorless Odor Flammable Unstable(explosive above 15psi) Left Handed Thread Acetone in a “sponge” = consistent

3 Types of Flames Carbonizing Neutral Oxidizing Too much acetylene Metal turns black and you can’t control the puddle Neutral equal amounts of O2 and acetylene Oxidizing too much O2 Dirty and bubbling, lots of sparks

Problems with OAW Torch pops, whistles, or goes out. If this happens you have experience backfire or a flashback Backfire vs Flashback Flashback is when gases burn in the TIP Black smoke comes out the tip, handle gets hot. Turn off torch valves - Turn off Tanks Let Ms. Haslam Know Check Equipment

Other Problems Too cold – bead sits on metal Too Hot- bead sags through the metal *holes Filler Rod Sticks – just wave the flame over it to get it unstuck. Dirty tips- get it cleaned

Parts of a OAW Setup Acetylene Side Acetylene cylinder Cylinder valve Red cylinder pressure gauge Regulator Hose pressure gauge Red hose Acetylene valve on torch Oxygen Side Oxygen cylinder Green cylinder pressure gauge Green hose Oxygen valve on touch

Torches Cutting vs. Welding Oxygen blaster 3 torch valves Oxygen Acetylene Oxygen Blaster Welding 2 torch valves Oxygen & Acetylene Rose Bud Heat Up

What are the two gauges on the regulator used for? Regulators What are the two gauges on the regulator used for? Tank Pressure Hose Pressure

Setting Up the OxyFuel ***Shut down:*** Check regulator thumb screws Turn on the oxygen valve all the way Set the correct oxygen working pressure Open acetylene cylinder valve one half turn Set the correct acetylene working pressure Light the flame Shut down the flame (Fuel first) Turn of the acetylene cylinder valve Empty acetylene hoses until gages register zero Turn off the oxygen cylinder valve Empty the oxygen hose until gages register zero Loosen regulator thumbscrews. ***Shut down:*** To shut of a torch correctly, first close the acetylene valve on the torch then close the oxygen valve

Misc Safety Info Hood Shades Potential Hazards Shock Fumes U rays Arc / Mig = #10 OxyFuel = #5 Potential Hazards Shock Fumes U rays Spark spatter Fire and explosion

Questions??

Review for the Test