What is a Spot Welder?
A spot welder uses two clamping electrodes to send an electrical current through two or more pieces of metal. A natural resistance to electricity causes the metal between the electrodes to heat up and a localized fusion is formed. The fused area is referred to as a spot weld. Does this Spark an idea?
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Difference Between Spot Welding And Inert Gas Welding
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Unlike inert gas welding, spot welders do not require a shielding gas to eliminate weld contamination or filler metal to build up the weld.
A spot weld is a resistant weld that sits within the two pieces of metal. The finished weld is flush or slightly recessed to the exterior of the base metals and has a silvery or coppery appearance. The color of the spot weld will vary by the alloy of the metal being welded and the type of electrodes used to create the spot weld.
An inert gas weld is built up in a gap between two pieces of metal. The finished weld is humped up above the base metal and is easily visible. The high amount of heat generated by inert gas welding can cause the base metal to warp and twist.
Types Of Spot Welders
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There are two types of spot welders: hand-held and stationary. Both types have the same components and fuse metal the same way, but they are designed for different purposes.
Hand-held spot welders offer portability, which makes them the perfect candidate for repairs to equipment that is not in the immediate area of a stationary spot welder. The main drawback with a handheld spot welder is its lack of a cooling system. The excess heat causes the electrodes to wear faster and also reduces the speed at which spot welding can be performed.
Stationary spot welders are designed for high production and use a coolant--generally water--which circulates inside the electrodes to reduce heat buildup. Other features seen in stationary spot welders are adjustments for weld time, electrode clamping pressure and metal thickness.
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Parts of a Stationary Spot Welder
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Stationary spot welders consist of a base, clamping arms, two electrodes, foot pedal and adjustment controls. The adjustment controls are located on the base and the spot welder is mounted on top of the base.
The spot welder has two clamping arms that protrude from the front of the stationary unit. The spot welder's stationary lower arm is used to balance the pieces to be spot welded. The upper clamping arm pivots to hold the pieces in place, while the electric current is passed through the two pieces of metal.
How To Use A Spot Welder
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Inspecting the spot welder is the first step in making a spot weld. Visually inspect the electrodes to make sure that they have relatively sharp points that are flat and relatively the same size. Next, turn on the power and water and inspect the spot welder for water leaks. Water leaks will reduce the spot welder's performance and create an electrical hazard.
Set the adjustments to the correct settings for the metal thickness and place the two pieces between the electrodes. Depress the foot pedal to make the spot weld; before you release the foot pedal, spin the metals slightly to break them free from the electrodes. Failure to properly free the electrodes can cause the electrodes to pull free of the spot welder and damage the electrode seat on the lower arm.
Spot Welder Care
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Caring for a spot welder is a simple process. It is important to check the water and electrical connections and keep the pivot points of the upper clamping arm greased.
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