GMAW Fundamentals Gas Metal Arc Welding Metal Inert
- Slides: 18
GMAW Fundamentals Gas Metal Arc Welding Metal Inert Gas By: Wanda Sue Benton ESAB University & Florence-Darlington Technical College
Introduction v GMAW is defined as arc welding using a continuously fed consumable electrode and a shielding gas. v GMAW is also known as MIG (Metal Inert Gas). v Produces high-quality welds v Yields high productivity
Advantages v Large gaps filled or bridged easily v Welding can be done in all positions v No slag removal required v High welding speeds v High weld quality v Less distortion of work piece
Types of Metal Transfer The basic GMAW process includes three distinctive process techniques: Short Circuit (Short Arc) 2. Globular Transfer 3. Spray Arc Transfer 1.
Short Circuit (Short Arc) v Operates at low voltages and welding current v Small fast-freezing weld puddle obtained v Useful in joining thin materials in any position, as well as thick materials in vertical and overhead positions v Metal transfer occurs when an electrical short circuit is established
Globular Transfer v Welding current and wire speed are increased above maximum for short arc v Droplets of metal have a greater diameter than the wire being used v Spatter present v Welding is most effectively done in the flat position when using globular transfer
Spray Arc Transfer v Occurs when the current and voltage settings are increased higher than that used for Globular Transfer v Used on thick sections of base material, best suited for flat position due to large weld puddle v Spatter is minimal to none
Manual GMAW Equipment v Three major elements are : 1. ) Welding torch and accessories 2. ) Welding control & Wire feed motor 3. ) Power Source v GMAW equipment can be used either manually or automatically
WIRE CONTROL & WIRE FEED MOTOR POWER SOURCE
Welding Torch & Accessories v The welding torch guides the wire and shielding gas to the weld zone. v Brings welding power to the wire also v Major components/parts of the torch are the contact tip, shielding gas nozzle, gas diffuser, and the wire conduit
GAS DIFFUSER NOZZLE TRIGGER CONTACT TIP INSTALLED COMPONENTS
Welding Control & Wire Feed Motor v Welding control & Wire feed motor are combined into one unit v Main function is to pull the wire from the spool and feed it to the arc v Controls wire feed speed and regulates the starting and stopping of wire feed v Wire feed speed controls Amperage
WIRE FEEDER
Power Source v Almost all GMAW is done with reverse polarity also known as DCEP v Positive (+) lead is connected to the torch v Negative (-) lead is connected to the work piece v Provides a relatively consistent voltage to the arc v Arc Voltage is the voltage between the end of the wire and the work piece
POSITIVE TERMINAL NEGATIVE TERMINAL
Shielding Gases v Purpose of shielding gas is the protect the weld area from the contaminants in the atmosphere v Gas can be Inert, Reactive, or Mixtures of both v Gas flow rate is between 25 -35 CFH v Argon, Helium, and Carbon Dioxide are the main three gases used in GMAW
FLOW METER CFH PRESSURE ADJUSTMENT KNOB CYLCINDER PRESSURE GAUGE
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- Gmaw equipment.
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- Shielded metal arc welding definition
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