1. Welding

2. Intermingling of molecules (cohesion) is any welding process

3. 5 Categories of welding processes
1. Arc
2. Oxyfuel Gas
3. Resistance
4. Solid State
5. Other (unique)

4. Arc
SMAW
GMAW
GTAW
Submerged arc
Electctroslag
Electrogas
Narrow gap
Stud arc
Arc spot
Plasma arc
Underwater SMAW
Oxyfuel Gas
Oxyfuel gas (with various fuels)
Self generating oxyhydrogen
Solid pellet oxyfuel gas
Resistance Spot Projection Seam Butt Seam Upset Flash Percussion Metal Foil Metal Fiber High Frequency Solid State
Coextrusion
Cold
Explosion
Forge
Friction hot pressure
Inertia
Roll welding
Ultrasonic
Other
Thermit
Electron beam
Laser beam

5. Arc Welding Processes (Consumable Electrode)
Developed in the mid-1800s
Heat obtained through electrical energy

6. Shielded Metal Arc Welding (SMAW)
“Stick welding”
Electric arc generated between tip of flux coated electrode and the work piece.
Electrode coating (flux) produces a shielding gas to protect the molten (liquid) metal from oxygen (oxidation)
Flux also collects and floats impurities to the top of the weld (called “slag”) and assists in controlling cooling of the weld
Electrode metal should be same as the workpiece
Engr 241-R1

7. Engr 241-R1

8. Electric arc between flux covered electrode and base metal
11/14/2018
Electric arc between flux covered electrode and base metal

9. Engr 241-R1

10. SMAW: 3 Current Settings
(DCEN) electrode negative
Workpiece positive, electrode negative.
Sheet metals - shallow penetration, gap joints.
(DCEP) electrode positive
Electrode positive, workpiece negative.
Deeper penetration.
(AC) Alternating current – combination of both
Engr 241-R1

11. Engr 241-R1

12. SMAW Advantages: Limitations: low cost equipment simple & portable
Easy to apply to many different applications & metals
Limitations:
less efficient than MIG
frequent starts and stops
high metal waste (stub loss)
Engr 241-R1

13. GMAW:
Formerly MIG (Metal Inert Gas)
Constant voltage DC Machine

14. Gas Metal Arc Welding (GMAW)
Uses a shielding gas from a gas cylinder
(no flux coated electrode)
Shielding gasses used to shield the arc to prevent oxidation
Argon, helium, carbon dioxide, or mixture
Wire fed from a spool automatically through nozzle into arc.
Engr 241-R1

15. Engr 241-R1

16. GMAW
Advantages
fast process - economical, twice the productivity as SMAW
can be easily automated (robots)
less skill required than stick
Limitations
Higher equipment cost
More complex machine set up
Difficult to reach smaller, (tight) areas
Wind can blow shielding gas if used outside
Engr 241-R1

17. Engr 241-R1

18. Engr 241-R1

19. Hazards / Safety , Protective clothing and shielding

20. Chief hazards to be avoided in arc welding:

21. 1. Radiation from the arc, ultraviolet and infrared rays
Never look at an arc from any distance unless your eyes are protected by properly shaded lenses
Without a proper shaded lens your eyes will be “burned” - feels like your eyes are full of sand – very uncomfortable
Seek medical attention
Safety:
Welding helmet with correct lens

22. Welding Lens Chart

23. Welding Lens Chart

25. 2. Flying sparks, globules of molten metal
Safety:
Cover pockets, trouser cuffs and unprotected skin,
Wear leather shoes or boots with safety toes

27. 3. Burns
Safety:
Wear heavy leather gloves, leather jacket, leather leggings - handle hot metal with tongs or pliers
Pass your hand over the metal before touching to see if you can feel heat radiating off the metal

29. 4. Electric shock Safety: Avoid moisture No standing in water
No welding on wet metal
Insulation on all components in good condition – no cracks, splits, etc.

30. 5. Fumes Safety: Avoid fume inhalation
Weld in a well ventilated area
Use exhaust fans
Weld close to open door if possible
Any exposure to welding gasses or dizziness
Move to fresh air

31. MSDS
A material safety data sheet (MSDS), safety data sheet (SDS),[1] or product safety data sheet (PSDS) is an important component of product stewardship and occupational safety and health. It is intended to provide workers and emergency personnel with procedures for handling or working with that substance in a safe manner, and includes information such as physical data (melting point, boiling point, flash point, etc.), toxicity, health effects, first aid, reactivity, storage, disposal, protective equipment, and spill-handling procedures. MSDS formats can vary from source to source within a country depending on national requirements.

32. MSDS

33. Care & storage of welding and safety equipment
Keep dry & clean
Inspect for holes and tears in gloves, aprons, shoes, etc
Welding Machines and Equipment
Perform routine maintenance
Oil and grease where needed
Check & replace cracked insulation on cables
Check that oxyfuel tanks are properly secured
Keep the work area free of debris and tools

34. Tack weld (usually every 3")

35. 5 Arc welded joint designs

36. Preparing joints before welding

37. 4 Welding positions:

38. Flat Position
Easiest
Least hazardous

39. Overhead Position
Hazardous: falling sparks & molten metal

40. Weld Defects:
By visual inspection a welder may find the following:

41. Weld speeds

42. Undercutting or Overlap at the toe of the weld

43. Porosity – small holes from trapped gasses weld speed too fast

44. Heat Settings

45. Good Welds

46. Multiple weld passes (beads)

47. Cutting Methods

48. Mechanical Cutting
Hack saw
Band saw
Abrasive Wheel

49. Thermal Cutting - heat Oxyfuel Gas Cutting
Process that uses a fuel gas combined with oxygen to produce a flame
Most common fuels used - acetylene (oxyacetylene)
Safety same as for arc welding

50. Equipment
Torch
Hoses
Tanks
Regulators

52. Cutting Torch allows for controlling and mixing oxygen and fuel gas

53. Gas Cylinder Safety caps on when moving secure to cart or wall
keep upright

55. Thermal Cutting Advantages Limitations portable flexible
low equipment cost
Limitations
limited to ferrous metals
rough surface finish
high distortion

56. Career Opportunities Welders Welding Inspectors Welding salespersons
Welding shop owners
Welding engineers
Educators

57. American Welding Society (AWS)
Certification
Conferences
Education