Fuel economy, energy efficiency, and vehicle safety top the list of concerns for many drivers, as well as automotive designers. Any number of automotive design and manufacturing techniques can help to achieve those goals, including one lesser known welding technique.

Stud welding is not a widely known technique but it's vital for improving the performance and strength of countless products, while lowering assembly costs for cars as well as manufacturing and fabrication costs for electrical transformers, commercial buildings, and bridges.

Stud welding is a form of drawn arc welding where in a split second, a fastener or specially formed nut is welded onto another metal part. Used for any weldable grade of steel, stud welding was invented in the shipyards of San Francisco during WWII, and it is used primarily to anchor concrete floors and bridge decking to structural steel frames. However, this technique is especially versatile and can be used in hundreds of applications, such as auto bodies, electrical panels, and commercial and industrial building construction. Stud welding is also used to attach components to a particular product in manufacturing of off-road construction equipment, highway trucks, trailers, power plants, and more.

This type of welding has proven particularly beneficial in the power-generation market for repairing coal-fired power plants, which generate energy through a complex process. For example, many U.S. energy companies rely on stud welding to anchor refractories and for other heat-transfer purposes. Each plant combusts coal in giant furnaces, generating temperatures that can reach up to 1,600° F. Then, the extraordinary heat is transferred via the stud to water tubes, creating steam that will be the driving force for the turbine generator. This demanding application requires the studs to be made of hard, weldable material that can withstand the effects of oxidation and abrasion that could continually erode boiler studs.

New material for weld studs

As a result of recent research and lab work, Nelson Stud Welding has developed a patented material for weld studs used in coal-fired power generation boilers. Nelson is a unit of the Doncasters Group, a global engineering company that manufactures precision components and assemblies for aerospace, industrial gas turbine, specialist automotive, petrochemical, construction, industrial, transportation and recreation markets.

This new material resists effects of oxidation and erosion in the cyclone furnaces and in the firebox, which extends the service life of both the studs, and the refractory material that these studs hold in place.

Patented by Nelson Stud, this new material can lower energy costs by reducing the frequency that a typical coal-fired plant shuts down the boiler to maintain, or repair the weld studs. The breakthrough will extend and enhance the longevity of coal-fired plants, while reducing the overall operating costs. Early testing shows this new material will extend the life of the studs by nearly four times. Another benefit of this new stud is that it runs cooler, transferring heat more effectively than stainless steel, thereby allowing the boiler to operate more efficiently.

Longer life for the studs means utilities can extend periods between outages, thereby reducing a utilities' maintenance and operating costs, and, cost avoidance of purchased power necessary when a boiler is shut down for maintenance.

What makes stud welding unique?

Not long ago manufacturers typically relied on projection welding, or MIG welding, to hold steel components in place. However, this application brings its own challenges. First, traditional welding requires manual intervention from skilled welders. The welder must move the work pieces to the welding machine, clamp the part in place, using expensive fixtures, and then weld the part in place.

Alternatively, with stud welding much of the work is done automatically. The welding tool is taken to the material location. When the welder presses the stud against the workpiece and initiates a weld, the system senses this connection, lifts the stud via a solenoid or servo drive to create an arc, forming molten material where the arc has touched. The electromagnetic system then releases the stud, and a spring or servo motor drives the fastener into a molten pool where it creates an exceptionally robust bond that's stronger than the base material and the stud. By creating a great deal of heat across a larger cross-sectional area of the base material, the welder creates stronger results. The weld will never fail, because it is a 100% cross-section of the stud material. The strength of the weld is crucial to ensuring the safety of the resulting product, be it a commercial building, a bridge, or a car.