Welding - Brent Payne

Welding - Brent Payne

Welding Intermingling of molecules (cohesion) is any welding process 5 Categories of welding processes 1. 2. 3.

4. 5. Arc Oxyfuel Gas Resistance Solid State Other (unique)

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

Arc Welding Processes (Consumable Electrode) Developed Heat in the mid-1800s 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

02/26/2020 Electric arc between flux covered electrode and base metal 9 Engr 241-R1

10 SMAW: 3 Current Settings (DCEN) Workpiece positive, electrode negative. Sheet metals - shallow penetration, gap

joints. (DCEP) electrode negative electrode positive

Electrode positive, workpiece negative. Deeper penetration. (AC) Alternating current combination of both

Engr 241-R1 11 Engr 241-R1 12 SMAW

Advantages: 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 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 GMAW 16

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

Hazards / Safety , Protective clothing and shielding Chief hazards to be avoided in arc welding: 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 Welding Lens Chart

Welding Lens Chart 2. Flying sparks, globules of molten metal Safety: Cover pockets, trouser cuffs and unprotected skin,

Wear leather shoes or boots with safety toes 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 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. 5. Fumes Safety: Avoid

Weld in a well ventilated area Use exhaust fans Weld close to open door if possible Any fume inhalation

exposure to welding gasses or dizziness Move to fresh air 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. MSDS Care & storage of welding and

safety equipment 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 Tack weld (usually every 3")

5 Arc welded joint designs Preparing joints before welding 4 Welding positions: Flat Position Easiest

Least hazardous Overhead Position Hazardous: falling sparks & molten metal

Weld Defects: By visual inspection a welder may find the following: Weld speeds Undercutting or Overlap at the

toe of the weld Porosity small holes from trapped gasses weld speed too fast Heat Settings Good Welds

Multiple weld passes (beads) Cutting Methods Mechanical Cutting Hack saw Band saw

Abrasive Wheel 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 Equipment Torch Hoses Tanks Regulators

Cutting Torch allows for controlling and mixing oxygen and fuel gas Gas Cylinder Safety caps

on when moving secure to cart or wall keep upright Thermal Cutting Advantages

portable flexible low equipment cost Limitations

limited to ferrous metals rough surface finish high distortion Career Opportunities Welders Welding

Inspectors Welding salespersons Welding shop owners Welding engineers Educators American Welding Society (AWS) Certification

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