If you already know how stud welding works, the next question is usually which stud welding machine you actually need. Capacitor discharge (CD) and drawn arc systems both create strong, fast welds, but they are built for different jobs. (If you are new to the process, start with our Back to Basics guide.)
Choosing the right stud welding equipment comes down to a handful of practical questions about your parts.
1. How Thick Is Your Base Material?
This is often the deciding factor.
CD stud welders are designed for thin sheet metal. The weld happens in a few milliseconds, so very little heat reaches the material. That makes CD the go-to choice for light gauge work.
Drawn arc machines are designed for thicker material. A common guideline is that the base metal should be at least one third the diameter of the stud weld base. That keeps the arc from burning through or distorting the part.
2. What Stud Size and Load Do You Need?
CD studs are typically used in smaller diameters, up to about 3/8 inch or M10. They work well for:
- mounting panels
- attaching components
- holding insulation and electrical hardware
Arc weld studs are available in much larger diameters. They produce a full cross section weld supported by a fillet formed inside the ferrule. For structural connections, heavy brackets and high load applications, drawn arc is usually the right choice.
3. Does the Reverse Side Need to Stay Clean?
If the other side of the part is visible, painted or finished, CD welding has a major advantage. Its short weld cycle leaves minimal marking on the reverse side. That is why CD is common on:
- enclosures
- appliances
- signage
- architectural panels
Drawn arc welding puts more heat into the part, so some reverse side marking is expected on thinner material.
4. What Is the Surface Condition?
CD welding needs clean, flat surfaces for consistent results.
Drawn arc studs carry flux at the weld end, and the process is generally more tolerant of surface conditions. Even so, cleaning the weld area is still good practice.
5. What Power and Portability Do You Need?
CD stud welding machines are typically compact and portable, and many run on standard single phase power. That makes them easy to move around a shop or bring to a job site.
Drawn arc machines need significantly more power. Plan for suitable electrical supply or a proper power source before bringing one into your operation.
Quick Comparison
| CD Stud Welder | Drawn Arc Stud Welder | |
|---|---|---|
| Base material | Thin sheet | Thicker plate |
| Typical stud size | Smaller diameters | Small to large diameters |
| Reverse side marking | Minimal | More likely on thin material |
| Ferrules | Not used | Used with most studs |
| Best for | Finished panels, light fastening | Structural and heavy load work |
Still Deciding?
Many shops handle both thin and heavy work, and some end up running both types of machines. The best way to decide is to test with your actual parts. Browse our stud welding equipment or ask about our rental fleet if you want to trial a machine on a real project.
Stud Welding Machine FAQ
What is the main difference between CD and drawn arc stud welding?
CD uses a very fast discharge for thin material. Drawn arc uses a longer controlled arc for thicker material and larger studs.
Can a CD stud welder weld thick steel?
Yes, but CD is limited to smaller studs. Drawn arc is usually better for heavy loads.
Do CD studs need ferrules?
No. Ferrules are used with drawn arc welding.
Which stud welder leaves fewer marks?
CD welding leaves far less marking on the reverse side of thin material.
Can one machine do both CD and drawn arc?
They are different processes, so most shops use a separate machine for each.
Get Help Choosing Your Stud Welding Machine
Tell us about your material, stud size and production volume, and the Davis Stud Welding team will recommend the right stud welding machine for the job. Call 1 (855) 720-2977 or contact us today.