Welding 101

Objectives Upon successful completion of this unit of study, you will be able to … Identify definitions and terminology associated with welding Demonstrate safe working habits in the welding environment Name the parts and types of welds and weld joints Interpret basic welding symbol information Identify opportunities available to welders SECTION OVERVIEW: This slide is included to explain the objectives of this unit of study. TEACHER NOTES: Teachers could use this opportunity to give a high-level overview of the importance and application of welding in today’s society.

What is it? Definition A joining process that uses heat, pressure, and/or chemicals to fuse two materials together permanently.

Why Learn to Weld? Welding can help build a successful career so you can get the things you want in life Skilled welders are in demand – people use things that are welded everyday! Welding can be fun and safe It is challenging and high-tech

STEM Connection Many of the same concepts you learn in other classes are practiced in welding. In what other classes might you study the following terms? 75/25 – gas mixture Volts Amps Degree/hr – cooling rate In/min Angles/degrees Metallurgy Fillet size Current Tension Compression Tensile strength Yield Blueprints Depth/width ratio Preheat temperature Cubic feet per hour

Careers in Welding Job opportunities in welding are changing … Welding can be valuable as a job skill or as a full-time job Engineering Racing Industrial Sales Farm Repair and Fabrication Production Welding Military Teaching Maintenance Robotics Ironworker/ Skilled Trades Auto Technician Artist Metal Sculpting Owning Your Own Business

How Much Money Can You Make? Recent statistics show that some welding jobs pay $25.00 per hour Local employers pay around $13-$22 83% of people with welding jobs were offered medical benefits - Higher than any other work sector except government

Job Openings http://www.indeed.com/q-Welding-l-Manitowoc-County,-WI-jobs.html

Welder vs. Weld Operator One who performs a manual or semiautomatic welding operation Weld Operator One who operates adaptive control, automatic mechanized or robotic welding equipment.

Methods of Application MA: Manual Welding SA: Semiautomatic ME: Mechanized Welding AU: Automatic Welding

MA: Manual Welding Welding with the torch, gun, or electrode holder held and manipulated by hand. Oxy-fuel welding Gas Tungsten Arc Welding (GTAW) Shielded Metal Arc Welding (SMAW)

SA: Semiautomatic Welding Manual welding with equipment that automatically controls one or more of the welding conditions Gas Metal Arc Welding (GMAW)

ME: Mechanized Welding Welding equipment that requires manual adjustment of the equipment controls in response to a visual observation.

AU: Automatic Welding Welding with equipment that requires only occasional or no observation and no manual adjustment of controls. Robots

Electrical Terms in Welding Voltage pressure, force, or push Volts Current flow of electron Amps Resistance hinders current flow Ohms DCEP Direct Current Electrode Positive DC+ Straight polarity (-) to (+) DCEN Direct Current Electrode Negative DC- Reverse Polarity (+) to (-) AC Alternating current Changes polarity 120/second

Constant Voltage – CV Welders Welding Circuit Consists of Power Source, Wire Feeder, and Work and Electrode Cables/Leads Voltage is Proportional to Arc Length Current Changes Dramatically to Maintain Constant Arc Length 4

Constant Current – CC Welders Welding Circuit Consists of Power Source, Voltage Sensing Wire Feeder, Work and Electrode Cables/Leads Voltage is Proportional to Arc Length Current Remains Constant Even for Changes in Voltage Due to Changes in Arc Length 4

Math Terms in Welding IPM Travel Speed = Inches per Minute Travel Speed The speed the electrode moves along the base material IPM Wire Feed Speed= Inches per Minute Wire Feed Speed The speed at which the wire is fed during wire welding Lbs/hr = Pounds per Hour Electrode deposition rate CFH= Cubic Feet per Hour Shielding gas flow rate (wire welding) PSI= Pounds per Square Inch Tensile strength of a material and the pressure in gas cylinders L = Leg Fillet size measurement % = percent Shielding gas mixture composition

PPE includes: Hat or Beanie #12-14 Mask Safety Glasses Ear Plugs Jacket Gloves Jeans Boots

Welding Safety List PPE head to toe __________________ __________________ __________________

Common Welding Tools Clamps Magnets Side Cutter Wire Brush Slag Hammer

Metal Preparation A real welder takes the time! This should take longer than the weld Clean, clean, clean! Joint fit-up. Debur sharp edges Bevel material ¼” or thicker Preheat material ½” or thicker

16 gauge = .062″ 14 gauge = .078″ 12 gauge = .105″ 10 gauge = .135″ SHEET: measured by gauge (.0068″) to (.2391″) PLATE: measured by inch rule (1/4” and up) For example, steel gauge and measurement in inches: 16 gauge = .062″ 14 gauge = .078″ 12 gauge = .105″ 10 gauge = .135″ PLEASE NOTE: As the gauge number gets smaller … the material thickness gets larger.

Welding Safety HOT PARTS can burn. FUMES AND GASES can be hazardous. ARC RAYS can burn eyes and skin. WELDING can cause fire or explosion FLYING METAL or DIRT can injure eyes. BUILDUP OF GAS can injure or kill. ELECTRIC AND MAGNETIC FIELDS (EMF) can affect Implanted Medical Devices. NOISE can damage hearing. CYLINDERS can explode if damaged.

Welding Safety FIRE OR EXPLOSION hazard. FALLING EQUIPMENT can injure. OVERUSE can cause OVERHERATING FLYING SPARKS can injure. MOVING PARTS can injure. WELDING WIRE can injure. BATTERY EXPLOSION can injure.

AWS/ANSI Lens Shade Numbers

The Arc Welding Circuit 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

Duty Cycle “Length of time a welder can be used continuously at its rated output in any 10 minute interval” Every welder has a duty cycle (60-80% common) TRHS Lincoln V350-PRO are 60% duty cycle May weld 6 minutes out of a 10 minute interval Fan kicks on and robes amperage

5 Basic Welding Joints

Welding Joints Can you identify theses joints?

AWS: Welding Positions 1: Flat 2:Horizontal 3: Vertical 4: Overhead 5&6: Pipe G: Groove Weld F: Fillet Weld

Electrode Travel Push, Pull Up, Down Lead Angle Work Angle Travel Speed Arc Length IMPORTANT: Weld bead profile is affected by electrode angle, arc length, travel speed, and thickness of base metal.

Push Vs. Pull Push Pull Push weld puddle Deep Penetration Less weld buildup Pull Pull weld puddle Less Penetration More weld buildup

Up vs. Down Vertical down is uncommon Heat rises making the puddle easier to control Arc hard to see

Travel Angle Also commonly called Lead Angle The travel (lead) angle is the angle between the electrode and the plane perpendicular to the weld axis 20-30°

Work Angle The work angle is the angle between the electrode and the work as depicted on the left Work angles can vary depending on the position the weld is being made in 90°

Work vs. Travel

Arc Length The distance the arc stretches from the electrode to the work-piece. Distance varies between processes

Bead Manipulation Stringer Weave Whip (6010, 6011, 6013 only)

Travel Speed The travel speed is the speed at which the electrode moves along the base material while welding Too fast of a travel speed results in a ropey or convex weld Too slow of a travel speed results in a wide weld with an excessive metal deposit End of Weld The travel speed impacts the shape of the bead.

Test Your Knowledge Identify good, fast, slow

Acronym used to recall proper welding technique C.L.A.M.S Acronym used to recall proper welding technique C…Current (DCEP, DCEN, AC) L….Length of arc (Drag, 1/16, 1/8, ½”, etc.) A…Angles (Travel angle, work angle) M…Manipulation (Straight, weave, whip, etc.) S…Speed of Travel (How fast you move)

Types of Welds Tack Weld Intermittent (Stitch) Weld Groove Weld Fillet Welds Plug or Slot Weld Multipass Welds Root Pass Hot Pass Fill Pass Cover Pass

Tack Welds Temporary but very important! Small enough to be welded over Strong enough to hold metal in position Position every 3-4 inches Tack all sides if possible

Tack Welds Tack welds prevent distortion and warping Tack weldment to table if practical

Intermittent (Stitch) Welding Welder doesn’t weld entire joint Allows joint variation / flexibility Lowers production cost Reduces distortion

Grove Welds Welding pass that deposits filler material into base material. Butt Joint Face Weld

Fillet Welds A fillet is a closed weld, which means the base metal is not cut through to accommodate weld metal. The process of joining two pieces of metal together whether they be perpendicular or at an angle.

Fillet Weld Inspection Fillet welds should: Have a flat to slightly convex face Be uniform in appearance Have equal leg size Have good wash-in into base materials This is an example of a good fillet weld:

Plug /Slot Welds  A circular fusion weld made in the hole of a slotted lap or tee joint

Bead Overlap should cover ~ 75% of previous pass. Multi-Pass Welding Root Pass Hot Pass (within 5 min.) Fill Pass 4. Cover Pass 5. Cover pass 6. Cover Pass Bead Overlap should cover ~ 75% of previous pass.

Multi-Pass Welding Identify each pass (hot, fill, root, cover)

Weld Bead Terminology Concave vs. Convex Leg Toe Face Throat Root Fusion Zone

Concavity

Convexity

Parts of a Weld Heat Affected Zone Joint and Weld

Joint Profiles Cross sectional view of the weld

Welding Symbols Information that you needs to complete weld!

Weld Symbols

Heat-affected Zone (HAZ) Area of base metal which is not melted and has had its microstructure and properties altered by welding or heat. The heat from the welding process and subsequent re-cooling causes molecular change in the base metal.

Distortion Distortion: Metal expands with heat Warping: Contracts even more as it cools Impossible to get rid of it but able to manage it!

Controlling Distortion Quality tack welding Intermittent welding Weld little material as possible Clamp or secure weldment to table Alternate weld locations (front, back, front, etc) Cool in sand or heated oven Backstep welding

Back-step Welding Welding in short lengths reduces longitudinal bowing but increases welding costs (time)

Cooling Welds Always handle hot metal with a pliers Assume metal is hot at all times Sand - slow Air - medium Purge/Quench - Fast * Swirl figure 8 pattern

Discontinuities & Defects A flaw or flaws that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability. Discontinuity An interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect!

Types Discontinuities Misalignment Undercut Underfill Concavity or Convexity Excessive reinforcement Improper reinforcement Overlap Burn-through Poor Penetration Incomplete Fusion Surface irregularity Arc Strikes Inclusions Spatter Arc Craters Cracks Base Metal Discontinuities Porosity Heat-affected zone microstructure alteration Base Plate laminations Size or dimensions

Visual Inspection Knowing what discontinuities are, is the key to quality welds. It is important for a welder to produce and confirm a proper weld!

Good Weld Characteristics

Poor Weld Characteristics

Porosity Single Pore Uniformly Scattered Cluster Linear Piping

Overlap / Cold Lap Toes do not tie in metal Causes: Improper technique, low heat No amount of overlap is typically allowed.

Undercut Definition: Under fill along the toes of the weld. Cause: High amperage, electrode angle, long arc length, rust

Spatter

Burn Through Front Back