TIG Welding Introduction

Outline Background Advantages and Disadvantages Safety Preparation for TIG Welding Techniques for Basic Weld Joints TIG Shielding Gases Tungsten Electrode Selection Conclusion ENBE 499

Background What is TIG? Also referred to as GTAW Tungsten Inert Gas Also referred to as GTAW Gas Shielded Tungsten Welding In TIG welding, a tungsten electrode heats the metal you are welding and gas (most typically Argon) protects the weld from airborne contaminants ENBE 499

Background TIG welding uses a non-consumable tungsten Filler metal, when required, is added by hand Shielding gas protects the weld and tungsten ENBE 499

Advantages Welds more metals and metal alloys than any other process High quality and precision Pin point control Aesthetic weld beads No sparks or spatter No flux or slag No smoke or fumes ENBE 499

Disadvantages Lower filler metal deposition rates Good hand-eye coordination a required skill Brighter UV rays than other processes Slower travel speeds than other processes Equipment costs tend to be higher than other processes ENBE 499

Safety Electric shock can kill. Always wear dry insulating gloves Insulate yourself from work and ground Do not touch live electrical parts Keep all panels and covers securely in place Fumes and gases can be hazardous to your health. Keep your head out of the fumes Ventilate area, or use breathing device ENBE 499

Safety Welding can cause fire or explosion. Do not weld near flammable material Watch for fire; keep extinguisher nearby Do not locate unit over combustible surfaces Do not weld on closed containers Arc rays can burn eyes and skin; Noise can damage hearing. Wear welding helmet with correct shade of filter Wear correct eye, ear, and body protection ENBE 499

Preparation for TIG Welding Preparing the Weld Joint Many problems are a direct result of using improper methods to prepare the weld joint One of the most common is the improper use of grinding wheels Soft materials like aluminum may get embedded with abrasive particles resulting in excessive porosity Grinding wheels should be cleaned and dedicated only to the material being welded ENBE 499

Preparation for TIG Welding Preparing Aluminum for Welding Very susceptible to contaminants Surface oxide must be removed Special abrasive wheels are available for aluminum Stainless steel wire brushes recommended Both sides of the joint should be cleaned if it contains foreign material ENBE 499

Techniques for Basic Weld Joints Arc Length Arc length normally one electrode diameter, when AC welding with a balled end electrode When DC welding with a pointed electrode, arc length may be much less than electrode diameter ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Gas Cup Size Inside diameter of gas cup should be at least three times the tungsten diameter to provide adequate shielding gas coverage Picture on right shows example of gas cup size and torch position 1-Workpiece, 2-Work clamp, 3-Torch, 4-Filler rod, 5-Gas cup, 6-Tungsten electrode ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Arc Starting with High Frequency Torch position on left shows recommended method of starting the arc with high frequency when the torch is held manually By resting gas cup on base metal there is little danger of touching the electrode to the work After arc is initiated, torch can be raised to proper welding angle ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Manual Torch Movement ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Manual Torch Movement Torch and filler rod must be moved progressively and smoothly so the weld pool, the hot filler rod end, and the solidifying weld are not exposed to air that will contaminate the weld metal area or heat affected zone When arc is turned off, post flow of shielding gas should shield the weld pool, electrode, and hot end of the filler rod ENBE 499

Techniques for Basic Weld Joints Butt Weld and Stringer Bead Be sure to center weld pool on adjoining edges When finishing a butt weld, torch angle may be decreased to aid in filling the crater Torch and rod position for welding the butt weld and stringer bead ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Lap Joint Pool is formed so that the edge of the overlapping piece and the flat surface of the second piece flow together Torch angle is important because the edge will become molten before the flat surface Enough filler metal must be added to fill the joint as illustrated on the right Torch and rod position for welding the lap joint ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints T-Joint Edge will heat up and melt sooner Torch angle illustrated will direct more heat onto the flat surface Electrode may need to be extended further beyond the cup in order to hold a short arc Torch and rod position for welding the T-joint ENBE 499 *Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints Corner Joint Both edges of the adjoining pieces should be melted and the pool kept on the joint centerline Sufficient filler metal is necessary to create a convex bead as shown Torch and rod position for welding the corner joint ENBE 499 *Figure copied from “TIG Handbook”

TIG Shielding Gases Argon Helium ENBE 499

TIG Shielding Gases Helium Argon Good arc starting Good cleaning action Good arc stability Focused arc cone Lower arc voltages 10-30 CFH flow rates Helium Faster travel speeds Increased penetration Difficult arc starting Less cleaning action Less low amp stability Flared arc cone Higher arc voltages Higher flow rates (2x) Higher cost than argon ENBE 499

Conclusion TIG welding is an exciting skill that proves itself useful in countless applications Because it welds more metal and metal alloys than any other process, TIG welding should be regarded as an important tool where experience is the teacher Welding parameters and tungsten electrode selection tables are recommended values and should be used as a guideline Information presented here is only the tip of the iceberg, and further research and hands-on involvement should be pursued to be comprehensive ENBE 499

THANK U ENBE 499