B-9

OPERATION

B-9

No one can learn to weld simply by reading about it. Skill comes only with practice. The following pages will help the inexperienced welder understand welding and develop his skill. For more detailed information, order a copy of the book “New Lessons in Arc Welding.” (See Book Division section at rear of manual).

The operator s knowledge of arc welding must go beyond the arc itself. He must know how to control the arc, and this requires a knowledge of the welding cir- cuit and the equipment that provides the electric cur- rent used in the arc. Figure 3 is a diagram of the weld- ing circuit. The circuit begins where the electrode cable is attached to the welding machine and ends where the work cable cable is attached to the machine. Current flows through the electrode cable to the electrode holder, through the electrode holder to the electrode and across the arc. On the work side of the arc, the current flows through base metal to the work cable and back to the welding machine. The cir- cuit must be complete for the current to flow. To weld, the work clamp must be tightly connected to clean base metal. Remove paint, rust,etc. as necessary to get a good connection. Connect the work clamp as close as possible to the area you wish to weld. Avoid allowing the welding circuit to pass through hinges, bearings, electronic components or similar devices that can be damaged.

ELECTRODE HOLDER

WELDING MACHINE

AC OR DC POWERELECTRODE SO RCE AND

CONTROLS

ARC

WORK

WORK CABLE

ELECTRODE CABLE

The electric arc is made between the work and the tip end of a small metal wire, the electrode, which is clamped in a holder that is held by the welder. A gap is made in the welding circuit (see Figure 3) by hold- ing the tip of the electrode 1/16 - 1/8” (1.6-3.2mm) away from the work or base metal being welded. The electric arc is established in this gap and is held and moved along the joint to be welded, melting the metal as it is moved.

Arc welding is a manual skill requiring a steady hand, good physical condition, and good eyesight. The oper- ator controls the welding arc and, therefore, the quali- ty of the weld made.

What Happens in the Arc?

Figure 4 illustrates the action that takes place in the electric arc. It closely resembles what is actually seen during welding.

The “arc stream” is seen in the middle of the picture. This is the electric arc created by the electric current flowing through the space between the end of the electrode and the work. The temperature of this arc is about 6000°F (3300°C) which is more than enough to melt metal. The arc is very bright, as well as hot, and cannot be looked at with the naked eye without risking painful and possibly permanent injury. A very dark lens, specifically designed for arc welding must be used with the handshield or headshield whenever viewing the arc.

The arc melts the base metal and actually digs into it, much like water through a garden hose nozzle digs into the earth. The molten metal forms a pool or crater and tends to flow away from the arc As it moves away from the arc, it cools and solidifies. Slag forms on top of the weld to protect it during cooling.

Covering

FIG RE 3 - The welding circuit for (Stick) shielded metal arc welding.

Solidified Slag

Electrode

Arc

Shielding Gases

Weld Metal Base Metal

FIGURE 4 - The welding arc.

POWER-ARC 5500

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Lincoln Electric IM871-A manual What Happens in the Arc?, Welding arc
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IM871-A specifications

The Lincoln Electric IM871-A is a cutting-edge industrial welding machine that exemplifies the brand's commitment to quality, innovation, and efficiency. Designed specifically for professionals in various sectors, including manufacturing, construction, and maintenance, the IM871-A boasts a range of features that streamline the welding process while ensuring longevity and reliability.

One of the standout features of the IM871-A is its advanced inverter technology. This technology not only enhances the machine’s portability but also improves energy efficiency. The inverter design allows for a compact and lightweight unit without sacrificing power output, making it easier for welders to move around job sites while maintaining peak performance. Welders can expect to achieve high-quality welds with minimal spatter, ensuring a clean and professional finish.

The IM871-A is equipped with a multifunctional interface, allowing users to easily navigate through various settings and customize their welding parameters according to specific project requirements. This user-friendly display includes digital readouts for voltage and current, providing real-time information that aids in precision control. Such adaptability makes the IM871-A suitable for a wide range of welding applications, from thin sheet metal to heavier structural components.

Additionally, the Lincoln Electric IM871-A supports multiple welding processes, including MIG, TIG, and Stick welding. This versatility makes it an ideal choice for professionals who require a machine that can handle diverse tasks without the need for multiple setups or equipment. The welder's robust output range further enhances its capabilities, accommodating various materials and thicknesses for both ferrous and non-ferrous metals.

Safety is paramount in any welding operation, and the IM871-A incorporates several features designed to protect the user. These include built-in thermal overload protection, which prevents the machine from overheating during extended use, and an automatic voltage reduction system that ensures the welder remains safe while efficiently managing power.

In summary, the Lincoln Electric IM871-A is a powerful and versatile welding machine built to meet the rigorous demands of industrial applications. With its advanced inverter technology, intuitive user interface, multiple welding process support, and essential safety features, it stands out as a reliable choice for professionals aiming for quality and efficiency in their welding operations. Whether for onsite applications or workshop environments, the IM871-A is engineered to deliver exceptional performance and durability, solidifying its place in the competitive welding market.
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