Shielded Metal Arc Welding (SMAW)

What is SMAW? SMAW often referred to as “stick” or “manual” welding. Metal rod covered with flux that provides the shielding to protect the weld. Uses constant current power sources. Most widely used form of welding in the world. Used for fabrication of ships, pressure vessels, tanks, automobiles, and appliances.

SMAW Safety Eye Protection Proper Work Clothing Safety Glasses, welding helmet Proper Work Clothing Jacket, Coveralls, gloves Electrical equipment hazard Frayed connections, water, protecting yourself from becoming part of the circuit

SMAW Overview SMAW utilizes an arc welding machine to join 2 pieces of metal together. Electric Arc established between flux covered electrode and base metal. Heat from the arc melts metal and mixes with deposits of electrode.

SMAW Electrical Principles When welding SMAW, an electrical circuit is created. Electrical circuit; path taken by electrical current flowing from one terminal of the machine, through a conductor to the other terminal. Current; amount of electron flow through an electrical circuit

Conductor; any material through which electricity flows easily. Resistance; opposition of the material in a conductor to the passage of electrical current causing heat. Heat is caused in SMAW by an air/gas gap between the electrode and base metal

SMAW Electrical Terms Revisited Ampere (amp, or A): Unit of measuring electricity/ electron flow. Amperage: Quantity of electricity (amps) measured. Voltage: Electrical pressure that causes current to flow

Current Flow Alternating Current- electrical current where electrons flow in both positive and negative values Direct Current- electrical current that flows in only one direction. Polarity refers to the direction in which electricity is flowing. DCEP; Direct Current Electrode Positive DCEN; Direct Current Electrode Negative

SMAW Equipment Power Supply Must maintain constant current with only a light change in voltage Varying voltage and current will result in an uneven arc that creates spatter and uneven welds Multiple types of power supplies (generators, transformers, rectifiers, inverters)

SMAW Equipment Welding Leads: conduct current to and from the work piece. Lead with the electrode holder attached is called the electrode lead Lead with the workpiece connector attached is called the workpiece lead. Commonly but incorrectly referred to as the ground clamp.

SMAW Equipment Electrode Holders Handle-like tool that holds the electrode during welding. Receives amperage and directs it through the electrode to form an arc. Should be well insulated and free from defect.

SMAW Equipment Work Piece Connection Must be connected to work piece or bench to complete electrical circuit. Connections are made to be removable for easy mobility

SMAW Equipment Electrodes Consists of internal metal core, and an outer coating called flux. Metal core melts into molten base metal. Flux is turned into gas shield as it burns away. Several types and sizes of electrodes.

SMAW Equipment Welding Helmet Used to filter the intense UV light produced from the arc welding process. Needs to be at least a #10 shade Auto shade helmets can be set to a particular shade number and don’t need to manually change the filter lens

SMAW Equipment Clothing Pants and Jackets need to be thick to help protect skin and body from the heat and UV light produced from welding Gloves need to be thick and insulated Arms and legs must be covered at all times while using SMAW

Electrodes Electrodes are coated metal wire with the same composition as the base metal to be welded. 5 main classification groups Mild steel High carbon Special alloy steel Cast iron Nonferrous

Electrodes Flux coating contains various substances Components of flux serve multiple purposes Cleansing and deoxidizing agent in molten crater Release Carbon Dioxide to protect molten metal Form slag over deposited weld bead Provide easier arc starting, stabilization, reduce spatter Improve weld penetration

Electrodes Electrode Identification-AWS standardized numbering system Example= E6013 What does this number mean?

E6013 E= Electric Arc Welding 60 (first 2 digits)=Tensile strength in 1000/lbs 1 (third digit)= Welding Position 3 (fourth digit)= Type of flux/ welding current