1. The Science Of Welding
An integrated lesson

2. Topics to be Discussed Introduction
What is Arc Welding?
Why is Welding Important?
Why Learn to Weld?
Basic Electricity and the Science of Welding
Electricity
Energy Transfers
Changes of State
Chemical Reactions
Welding Safety
Careers in Welding

3. Introduction
Arc welding is a process used to join two pieces of metal together.
How does it work?
A welder creates an electric arc that melts the metal and filler rod to create a pool of molten metal that hardens to fuse the two pieces of metal together.

4. Introduction Why is welding important?
Many of the things you use need to be welded.
Your parent’s car
Power line towers
Your school desk
Your bicycle
dcist.com
assembly.state.ny.us

5. Introduction Why Learn to Weld?
Welding can help build a successful career to earn money to buy the things you want.
Skilled Welders are in high demand.
Welding is challenging and high tech.

6. Basic Electricity and the Science of Welding
Voltage – The electrical potential or pressure that causes current to flow
Measured in Volts
Current – The movement of charged particles in a specific direction
Measured in Amps
Polarity
DC- (Direct Current Electrode Negative)
DC+ (Direct Current Electrode Positive)
AC (Alternating Current)
DC+
DC - AC

7. Basic Electricity and the Science of Welding
The electricity flows from the power source, through the electrode and across the arc, through the base material to the work lead and back to the power source
Circuit – click on the link
to learn more.
Circuit Info.

8. Basic Electricity and the Science of Welding
Use the following links to learn how electricity works in a circuit
Conductors, Insulators, and electron flow
Current and Voltage in a Circuit
Resistance
Ohms Law

9. Basic Electricity and the Science of Welding
The electron flow you just learned about is what creates the arc in arc welding.
This is a form of electrical energy
How do we use that electrical energy to fuse metals together?

10. Basic Electricity and the Science of Welding
The energy transfers that take place in welding
Electrical The arc created by the
electric current is
converted into heat
Thermal because of the resistance of electron flow. The heat melts
the metal to fuse it together.

11. Basic Electricity and the Science of Welding
Here are some places to look to learn more about energy and energy transfers.
Forms of Energy
Energy Transformations

12. Basic Electricity and the Science of Welding
Changes of State and Chemical Reactions
During the welding process the metal changes states or forms.
What are the states of matter?
Solid
Liquid
Gas
Plasma
Click here to learn more about the changes of state

13. Basic Electricity and the Science of Welding
Changes of State and Chemical Reactions
So what changes of state occur during welding?
Initially the metal is a solid
When the arc starts the solid is converted into a liquid
Some of the liquid is converted into a gas vapor
When the arc stops the liquid cools to form a solid again – this is the newly formed weld joint
Solid Liquid Solid
(gas vapor)

14. Basic Electricity and the Science of Welding
Changes of State and Chemical Reactions
Chemical Reactions
During the welding process certain chemical reactions take place.
Hydrogen, Oxygen, and Nitrogen can react in the weld puddle and cause changes in the structure of the weld weakening the weld.
pt.chemicalstore.com

15. Welding Safety
Because of the chemical reactions, energy transfers, and electricity involved in welding proper safety must be addressed
Welding can be safe when sufficient measures are taken to protect yourself and others from potential hazards
Students should read and understand the following before welding:
Warning Labels
Material Safety Data Sheets (MSDS)
Students should also be familiar with the following information
‘Safety in Welding, Cutting, and Allied Processes’ (ANSI Z49.1)
Lincoln Electric’s ‘Arc Welding Safety’ (E205)

16. Welding Safety Understand and follow all warning labels found:
On welding equipment
With all consumable packaging
Within instruction manuals

17. Welding Safety Material Safety Data Sheets (MSDS) are:
Required by law and OSHA
Created by the manufacturer of a product per OSHA guidelines
Designed to inform users
Shipped with every box of consumable product
Available free online at:

18. Welding Safety MSDS outlines a product’s: Identity and composition
Potential hazards
Safe use
Handling information
Manufacturer contact information

19. Welding Safety
Protect yourself and others from potential hazards including:
Fumes and Gases
Electric Shock
Arc Rays
Fire and Explosion Hazards
Noise
Hot objects

20. Welding Safety Fumes and gases can be hazardous to your health
Keep your head out of the fumes
Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area
See product labeling and MSDS for ventilation and respirator requirements

21. Welding Safety Electric shock can kill
Do not touch live electrical parts
Primary Voltage –230, 460 volt input power
Secondary Voltage – 6 to 100 volts for welding
Insulate yourself from work and ground
Follow all warnings on welding equipment

22. Welding Safety Welding sparks can cause fires and explosions
Sparks and spatter from the welding arc can spray up to 35 feet from your work
Flammable materials should be removed from the welding area or shielded from sparks and spatter
Have a fire extinguisher ready
Inspect area for fires 30 minutes after welding

23. Welding Safety Welders must wear protective clothing for
Protection from sparks, spatter and UV radiation
Insulation from electric shock
Protective clothing includes …
Fire-proof clothing without rolled sleeves, cuffs or frays
Work boots
Welding gloves, jackets, bibs, and fire-proof pants
Welding cap, helmet and safety glasses
Ear protection – ear plugs and muffs

24. Careers in Welding Education Careers Penn College of Technology
Penn College Welding Video
Welding Schools
Careers
American Welding Society
Career Guide
Welding Jobs
pro.corbis.com

25. Careers in Welding
Here are some possible areas you can start a career in welding
Racing
Engineering
Farm
Auto Technician
Sculpting
Maintenance
Iron worker
Robotics
Production welder
Fabricator
And many more…

26. What to learn more?
Do you want to learn more about welding and how to weld? If so, go to the link below for more information on how to weld.
This is to be used if your school has access

27. Resources
All photographs are cited next to photograph