Introduction to Welding
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Transcript of Introduction to Welding
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 WeldingTo 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
• “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
SAFETY: Eye Protection
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
– 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?
• 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– 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?
• 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
Positive Cable
Negative Cable
Base Metal
Electrode
AC vs. DC Current
Parts of the SMAW Welder
Parts of a GMAW Welder
A B C D E F1. Welding current too low.2. Welding current too high.3. Arc too long.4. Welding speed too fast.5. Welding speed too slow.6. 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
– 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
Black smoke comes out the tip, handle gets hot.
Flashback is when gases burn in the TIP
-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
Acetylene Side1.Acetylene cylinder2.Cylinder valve3.Red cylinder pressure gauge4.Regulator 5.Hose pressure gauge6.Red hose7.Acetylene valve on torch
Oxygen SideOxygen cylinderCylinder valveGreen cylinder pressure gaugeRegulatorHose pressure gaugeGreen hoseOxygen valve on touch
Parts of a OAW Setup
Torches Cutting vs. Welding
• Cutting– Oxygen blaster– 3 torch valves
• Oxygen
• Acetylene
• Oxygen Blaster
• Welding– 2 torch valves
• Oxygen & Acetylene
• Rose Bud
• Heat Up
Regulators
What are the two gauges on the regulator used for?– Tank Pressure
– Hose Pressure
Setting Up the OxyFuel1.Check regulator thumb screws2.Turn on the oxygen valve all the way3.Set the correct oxygen working pressure4.Open acetylene cylinder valve one half turn5.Set the correct acetylene working pressure6.Light the flame7.Shut down the flame (Fuel first)8.Turn of the acetylene cylinder valve9.Empty acetylene hoses until gages register zero10.Turn off the oxygen cylinder valve11.Empty the oxygen hose until gages register zero12.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– Arc / Mig = #10– OxyFuel = #5
• Potential Hazards
• Shock
• Fumes
• U rays
• Spark spatter
• Fire and explosion
Questions??
Review for the Test