Mumbai University > Mechanical Engineering > Sem 3 > Production Process 1

Marks: 5M

Year: May 2016

Resistance welding is a thermo-electric process in which heat is generated at the interface of the parts to be joined by passing an electrical current through the parts for a precisely controlled time and under a controlled pressure (also called force).

Key advantages of the resistance welding process include:

• Very short process time
• No consumables, such as brazing materials, solder, or welding rods
• Operator safety because of low voltage
• Clean and environmentally friendly
• A reliable electro-mechanical joint is formed

There are an abundance of resistance welding applications used within a variety of industries

• The most common applications of large-scale resistance welding can be found in the automotive industry, aerospace industry, railway industry, food and beverage industry, nuclear industry, solar industry, material handling industry, military/defense industry, and the industrial and manufacturing industry.
• Resistance welding in the automotive industry is probably the most common. During vehicle assembly there are three resistance welding processes that are typically leveraged: spot welding, projection welding (a variation of spot welding) and seam welding (a variation of spot welding).
• Resistance welding in the aerospace industry is utilized to join parts made of certain metals that possess high strength, yet lightweight properties. Two of the most common alloys include Titanium and Inconel.
• Like the automotive industry, the aerospace industry also utilizes spot welding, projection welding and seam welding in production.
• Typical alloys used for resistance spot welding and seam welding include aluminum, steel, magnesium, titanium, steel, nickel and cobalt.
• Resistance welding in the aerospace industry is particularly advantageous due to the cost-savings it generates in replacement parts.

Limitations:

• Equipment complex, to be equipped with high technical level of maintenance personnel.
• Higher cost
• Large capacity and the majority of single-phase welder
• Unbalanced load on the grid causing serious damages
• Lack of simple and practical means of NDT
• Lap joints add weight and material
• Lower tensile and fatigue strength