Drawn arc stud welding and capacitor discharge (CD) stud welding are two different sides of the same coin. Both offer excellent results for non-invasive fastener welding, but they also use different methods to get the job done. The following takes a look at the advantages and disadvantages that arc and CD stud welding have to offer. In the end, you can use this information to decide which welding option works best for your needs.
Arc Stud Welding Pros and Cons
In drawn arc welding, a flux-impregnated stud is loaded onto the stud welding gun and a sacrificial ceramic ferrule is placed over its end. When the stud is placed over the workpiece, the welding gun energizes and lifts the stud just enough for an arc to form underneath. It only takes a brief moment for molten metal to pool underneath the stud, after which the weld is pressed onto the molten surface below and allowed to cool.
Arc stud welding offers several advantages. For starters, the welds themselves are exceptionally strong and resistant to vibration, breakage and other structural integrity issues. The arc welding process can also be used with a wide variety of studs in various sizes, making it exceptionally versatile for a number of critical applications.
In spite of the advantages offered by arc stud welding, there are some downsides when compared to CD stud welding:
- Arc stud welding can be done quickly, but it lacks the near-instant speed that the CD stud welding process offers. This factor could serve as a drawback for arc stud welding, resulting in a slight effect on productivity in certain fast-paced projects.
- Arc stud welds aren't ideal for use on thin metals, as the amount of heat and current could leave behind discoloration on thinner workpieces.
CD Stud Welding Pros and Cons
CD stud welding shares many similarities to its drawn arc counterpart, but there are plenty of noticeable differences that help set it apart. True to its name, CD stud welding relies on the swift and sudden burst of energy stored in its capacitors to create the arc needed to fuse the stud with its mating surface.
Since CD stud welding requires no ferrules or flux, the stud itself must feature a special projection on the end of the stud. During the welding process, the tremendous energy released vaporizes the projection, creating an arc that allows the stud and the surface to fuse effectively. Immediately afterwards, a spring-loaded mechanism locks the stud onto the workpiece.
There are plenty of advantages to this process:
- The CD stud welding process wins out when it comes to speed. In most cases, a CD stud weld can be completed in as little as 0.01 second, according to Assembly Magazine's Blake Hobson.
- The short welding time also ensures that there's little to no burn-through on the back side of the workpiece. This helps keep the workpiece cosmetically pristine, making CD stud welding the go-to method for projects where cosmetic appearances matter.
- CD stud welding can also be safely used on thin workpieces, thanks largely to the welding method's shallow penetration. According to Hobson, CD stud welds can be as shallow as 0.02 inches without any adverse effects.
In spite of its advantages, there's one caveat to CD stud welding that should be considered. Studs manufactured for CD welding are often smaller than their drawn arc counterparts. This could be a limiting factor in applications that require large studs.
By taking a look at the benefits and drawbacks of both drawn arc and CD stud welding systems, you'll be able to decide which stud welding process works best for your project needs.