Metal Fabrication Introduction to common welding and cutting processes 2015

Choosing the best weld process gas Why do we need a weld process gas? -Protects the weld pool -Assists in stabilising the arc -Assists in metal (droplet) transfer (MIG/MAG) -Helps maintain metallurgical properties of the material Also… -Influences productivity -Influences weld quality -Influences the working environmental MIG/MAG TIG 02_EN_M_Mar_2015

MIG/MAG Welding Metal Inert Gas (MIG) Inert  the process gas DOES NOT react with the weld material Metal Active Gas (MAG) Active  the process gas DOES react with the weld material Ar CO 2 O2O2 H2H2 N2N2 Can be 100% CO 2 Mixture of one or more of these gases in an inert base gas He

MIG/MAG Welding Equipment

MIG/MAG Welding Welding wire (electrode) Contact tip Weld Parent Material Weld process gas Gas shroud

MIG/MAG Welding Example of welding

TIG Welding Tungsten Inert Gas Inert  the process gas DOES NOT react with the weld material Ar Active  the process gas DOES NOT react with the weld material H2H2 Mixture (up to 5%) in an inert base gas TAG terminology not used Ar He

TIG Welding Equipment

TIG Welding Filler material Weld Parent material Weld process gas Tungsten electrode Gas shroud

TIG Welding

Summary MIG/MAG & TIG Independent input of filler wire... Requires a skilled operator Non-consumable electrode process Lower productivity / higher quality than MIG/MAG Semi-mechanized / robotic welding possible but not as common as in MIG/MAG Automatic feeding of filler wire Easy to use & highly productive Consumable electrode i.e. filler wire is the electrode Semi-mechanized / robotic welding (common) Can generate spatter - may require post-weld cleaning (time = cost) TIG MIG/MAG

Definition: Light Amplification by the Stimulated Emission of Radiation: LASER Laser Cutting is fast and precise Laser Cutting

Laser Gases (resonator gases – CO 2 lasers only) -Typically used for the laser beam either as a premixed cylinder or as individual cylinders -Low flow rates – small volumes Process assist gases (all laser types) -To assist in the removal of metal from the cut area -High pressures, high flow rates CO 2 N2N2 O2O2 N2N2 Carbon steel Stainless steel He

O2O2 N2N2 Ferrous materials: carbon steel Ar Non Ferrous: stainless steel (and aluminium) Reactive materials such as titanium Air Low cost – low-quality alternative Laser Cutting – process assist gases

Similar to TIG Welding Non-consumable Tungsten electrode Used a constricted plasma-arc created by an additional water cooled plasma nozzle Electrode protected inside the torch TIGPLASMA Plasma Arc Welding

Two distinct gas streams Plasma gas is inert  the gas DOES NOT react with the weld or the tungsten electrode Ar Weld process gas similar to TIG can be inert or active  the process gas DOES react with the weld material H2H2 Mixture (up to 15%) in an inert base gas Ar He

Plasma Arc Welding Tungsten electrode Gas shroud Plasma gas Nozzle Weld Weld process gas

Plasma Arc Welding Electric arc is the heat source Specialised welding process Independent input of filler wire but protected electrode and easy arc starting... more suitable than TIG for automation Uses a plasma and a weld process gas (inert / active- reducing) Non-consumable electrode process Mechanized / robotic welding common Common problem – no problems but relatively expensive and complex torches vs. TIG

Thank you tell me more