8.2 SMAW Equipment and Setup
David Ridge
Components
SMAW is one of the simplest welding processes as far as the amount of equipment needed. There are only four main components to the system:
- a welding power source,
- a workpiece lead,
- an electrode lead, and
- coated metal electrodes of the appropriate alloy.
The following sections discuss these components in detail.
Welding Power Source
A welding power source is a machine capable of producing the specialized electrical current necessary for arc welding. These machines can vary widely in design, capability, and size, but, in general, they can be divided into three types: transformers, inverters, and engine-driven varieties. You will often hear the welding power source called a welding machine or simply a welder on the jobsite.
Welding power sources will be discussed in greater detail later in this chapter, and they are also covered in Chapter 5: Welding Machines.
Workpiece Lead
The workpiece lead is used to make the electrical connection between the welding machine and the base metal. You may hear the workpiece lead called the work lead or a ground lead (although this is inaccurate).
Welding leads are made of many small strands of copper wire twisted together into a cable and covered in a protective rubber sheath. Welding leads vary in diameter and length depending on the welding application.
The workpiece lead is attached to the base metal using either a clamp or a lug. A lug can be connected to a threaded stud, which is then welded to the base metal. These clamps and lugs are usually made of copper or brass; however, you may see some clamps made of steel. Though less common, there are also magnetic work clamps.
The other end of the workpiece lead is connected to the welding machine via a special plug called a twist-lock connector. This plug inserts into a receptacle on the welding machine and then twists to lock it in place. If not connected in this way, the lead is usually attached using a lug, or in some cases, it is permanently wired into the machine.
Electrode Lead
The electrode lead runs from the welding machine to the electrode holder. This is the piece that the welder holds in their hand in order to make the weld. You may often hear this piece called the stinger or the whip.
The electrode holder transfers the welding current to the electrode. There are several styles of electrode holders, and the most common are the alligator clamp style and the twist-lock style.
Coated Metal Electrodes
The SMAW electrodes are metal rods commonly ranging from 9–18 inches in length, although longer ones may be found. These rods usually range from one-sixteenth of an inch to one-quarter of an inch in diameter. Larger diameters are available but are usually only used for special applications.
The rods are sheathed in a flux coating. The flux has several purposes, the first of which is to protect the weld from the atmosphere during welding. This is primarily accomplished by the gas cloud and the slag cove