How do you size a spot weld?

Diameter of the electrode contact surface should be slightly larger than the nugget diameter. For example, spot welding two sheets of 1 mm thickness would require an electrode with a contact diameter of 6 mm. In practice, an electrode with a contact diameter of 6 mm is standard for sheet thickness of 0.5 to 1.25 mm.

How thick can you spot weld?

Spot welding is primarily used for joining parts that are normally up to 3 mm in thickness. Thickness of the parts to be welded should be equal or the ratio of thickness should be less than 3:1. The strength of the joint depends on the number and size of the welds. Spot-weld diameters range from 3 mm to 12.5 mm.

How are spot weld nuggets measured?

In most manufacturing operations nuggets are tested by pulling the part or test coupon apart after welding. This is frequently done with a combination of hammer, pliers and chisel. Then the resultant pulled weld nugget is measured with a set of calipers in two directions, 90 degrees apart.

What is the typical size of a spot weld nugget?

According to the standard, AWS C1. 4M/C1. 4:2009, the diameter of the weld nugget for low carbon steel sheet with a thickness of 1 mm has to be between 3.1 and 4.4 mm. As a result, if the nugget diameter is within the range, the welding strength will be assured.

What is the tip diameter in spot welding?

Welding tip diameter is very important. The TITE-SPOT Pliers has the welding tips sharpened to 3/16″ diameter when new. The tips can be allowed to fatten to 1/4″ diameter before they need to be sharpened. Welding tips have a flat face when new.

Spot Welding Basics

How do you determine electrode size?

Generally the size of the electrode that should be used depends on the thickness of the part to be welded. For thin metals the electrode is only slightly larger than the metal to be welded. For example if a plate is of 2.0 mm thick the electrode of 2.5 mm should be used.

Are spot welds strong?

Spot welding is useful in many circumstances, although there are certain limitations. It can create only localized joins, which may not be particularly strong. The strength of a spot weld depends on the force and temperature that has been applied and on the cleanliness of the electrodes and metal.

How is Nugget Dia calculated?

How to calculate Diameter of Nugget? Diameter of Nugget typically defines weld strength in sheets of a given thickness is calculated using Diameter = 6*(Thickness)^1/2.

How do you calculate electrode force in spot welding?

The Electrode force is applied to the work piece by electrode to ensure that during the solidification, the nugget does not develop any porosity or crack and is represented as F = 876*(t₁+t₂) or Force = 876*(Thickness of First Material+Thickness of Second Material).

What is the nugget diameter?

The weld nugget diameter is defined as the average diameter of the major and minor button diameter determined by peeling one of the sheets back over the spot weld, leaving a hole in one sheet and a button of material attached to the other sheet.

What is Nugget in spot welding?

In resistance spot welding, “the welding of overlapping pieces of metal at small points by application of pressure and electric current” creates a pool of molten metal that quickly cools and solidifies into a round joint known as a “nugget.” Also see resistance spot welding.

How do you measure projection welding strength?

Strength of a projection weld can be calculated to a simple approximation by area of the dimple and assuming base metal properties for shear/tensile strength, based on type of loading during testing.

What causes sparks when spot welding?

Many companies assume that this is a normal condition. Some believe that the expulsion is actually hot oil or grease. The truth is that these sparks are droplets of molten metal coming from under the electrode or from between the parts being welded.

What is hold time in spot welding?

Definition. Hold time is the period of time programmed into the weld controller, typically between the end of weld time and the command to open the electrode. The actual hold time is the amount of time for which the electrode force is applied after current ceases to flow.

Is a plug weld stronger than a spot weld?

In automotive applications, plug welds are commonly used in place of spot welds when there is insufficient space to accommodate spot welding equipment. The resulting weld is often stronger than a spot weld.

What metals can you spot weld?

Copper can be spot welded. But not surprisingly, the standard spot welding copper electrodes do not work. Molybdenum and tungsten electrodes are the primary choices for spot welding copper. These metals have high electrical resistance and melting temperatures.

Can a spot welder shock you?

Can I get electrocuted by touching the weld cables or electrodes? – Luckily, No. For all concerned, the voltage for all resistance welding technologies is below the level where there would be a concern about electric shock. This includes CD, AC, DC, and HF models.

What is a good spot weld?

Other materials commonly spot welded include stainless steels (in particular austenitic and ferritic grades), nickel alloys and titanium. Although aluminium has a thermal conductivity and electrical resistance close to that of copper, the melting point for aluminium is lower, which means welding is possible.

What is the main factor when determining the size of an electrode?

Tensile strength. Welding current. Base metal thickness, shape and joint fit-up. Welding position.

Does size of electrode affect current?

With increasing electrode area, the ratios of voltage/current decreased nonlinearly, while the ratios of charge/voltage increased nonlinearly.

What is the difference between spot welding and projection welding?

Spot welding is particularly useful for corners and thin materials. Projection welding is more useful for thick metal materials and products that require an exceptionally strong weld, since less heat and pressure during the welding process yield a stronger joint.