Different materials are spot welded together?

The immediate reply is yes, but it may be neither easy nor advisable in certain cases if brittle structures are produced by the different metals mixing in the molten nugget.

In exacting austenitic stainless steel and carbon steel is not generally spot welded jointly since the resulting nugget arrangement risks being hard and brittle, though it can be studied and modified using the Schaeffer diagram and particularly conceived warmth treating cycles.

Materials having widely dissimilar properties need that a warmth balance be achieved by compensation. The additional conductive material, electrically and thermally, have to be heated extra as it provides fewer resistive warmth, and the warmth is lost more easily by conduction.

An ordinary method uses an electrode of smaller face diameter and superior resistivity facing the additional conductive material, or by inserting a foil of poorly conductive material among them.

Concerning the number of sheets weldable with a single nugget, usual practice advices not more than three layers, although four sheets are infrequently spot welded jointly. In any case the ratio of the thickest to the thinnest sheet should not go beyond three.

Arc, Spot Welding Techniques:

Welding has become an integral part of the lives of many people. Just like there are various different welding machines available, all the way from Diesel Welders to Pro-Arc's, there are also numerous welding techniques that can be used. In this article, we will cover some of the popular welding techniques like:

(1). Arc (2). Spot

Here, we will talk about why Arc welding is important. Arc welding is usually done by making use of a diesel welder. In arc welding, high electric voltage is used, instead of a gas torch. The arc, or the spark, created from the electrode rod, used by the welder, is transferred from one metal to the other metal. This in turn causes the metals to heat up and melt together which creates a bond or a weld amongst them. Arc welding is known to create cleaner, smoother, accurate and stronger welds.

The second technique to be discussed is the Spot technique. In this method, the two metal sheets are held together tightly by the electrodes. The surface area of contact between the electrodes and the materials is very small, and hence it is called 'spot' welding. When a large amount of current is passed through the electrodes, it heats up the spots to the point of melting, which results in a sturdy weld. This technique ensures that the rest of the metal isn't heated up unnecessarily and also takes lesser time.

Instructions of Spot Welding:

1). Slide the sheet metal gauge onto one edge of the sheet metal to determine the thickness of the metal. When the sheet metal fits snug in a sheet metal gauge slot, read the number above the slot. This will show the thickness of the metal.

2). Set the hold, weld, squeeze and off-time of the spot welder by locating the thickness of the sheet metal on the welding chart affixed to the spot welder.

3). Clean the tips of both the top and bottom electrode by sliding the file over each tip. To weld correctly, the tip of each electrode should have no black carbon deposits.

4). Put on your leather work gloves.

5). Turn on the spot welder and open the cold water supply valve to flow water through the electrodes.

6). Stack the two pieces of sheet metal on top of one another.

7). Set the stacked pieces of sheet metal on the bottom electrode of the spot welder.

8). Depress the pedal of the spot welder to lower the top jaw of the spot welder and weld the sheet metal.

9). Twist the welded sheet metal a quarter-turn before releasing the pedal to avoid pulling a welding electrode from its socket.

10). Attempt to pull the sheet metal apart. If the metal bends rather than pulls apart, the spot welder is set correctly. If the spot weld breaks, increase the weld time of the spot welder and repeat the listed steps until you achieve a proper spot weld.