Choose capacitor discharge (CD) studs for thin sheet – roughly 0.5 mm up to about 2-3 mm – when the reverse side must stay unmarked and cycle time matters; choose drawn-arc studs when the plate is thicker and the joint must carry heavier loads. This comparison is for manufacturing engineers selecting a stud welding process for enclosures, switchgear, automotive panels and HVAC sheet. It does not cover non-threaded insulation pins or capacity studs; and if your panel is thinner than 0.5 mm, neither process is right – move to adhesives or mechanical fasteners.
Where the wrong process choice surfaces
The cost of choosing the wrong stud process appears after the pilot line, in a sequence like this:
- The project team sizes studs by thread load and leaves the process unspecified on the drawing.
- The chosen process turns out to mark the cosmetic reverse face – or cannot weld through the coating.
- Nobody has cycle-time or equipment-cost data to judge a change at that stage.
- Engineering re-tests panels with the alternative process and waits for new stud samples.
- Launch slips while fixtures and gun setups are re-qualified.
- Decide the process against sheet thickness and face condition before fixtures are built.
Side-by-side on the process dimensions
| Dimension | CD (capacitor discharge) | Drawn-arc |
|---|---|---|
| Sheet thickness | Roughly 0.5 mm and up; thin sheet friendly | Thicker plate, roughly 2 mm and up |
| Reverse-side marking | None on correct settings | Visible witness mark common |
| Coated / painted panels | Welds through thin coatings | Usually needs bare metal |
| Weld time | 1–5 milliseconds | Longer arc time per stud |
| Load capacity | Moderate – limited by sheet | Higher – full fusion weld |
| Equipment | Compact CD gun + capacitor unit | Heavier arc unit, often fixture-based |
| Stud types | Flanged (PT), non-flanged (IT), metric/inch | Full-size threaded, deformed, shear connectors |
Our flanged CD weld stud specification lists the material set – mild steel copper plated, 304 stainless, aluminium AlMg3, lead-free brass – and the parent materials each welds to, from coated steel to copper.
Decision rules
- Condition: cosmetic or gasketed reverse face. CD wins; drawn-arc’s witness mark disqualifies it on visible panels.
- Condition: thin sheet below ~2 mm. CD; drawn-arc burns thin panels.
- Condition: heavy structural load on thick plate. Stop – drawn-arc territory, and the stud selection changes with it.
- Boundary: very thin or very hard coatings. Run trial welds on your actual panel – coating behaviour is the one variable charts predict poorly.
Validate on your panel, not on catalogue data
The published process ranges are starting points; the decisive test is trial welds on your sheet with its actual coating, followed by bend or torque tests to your standard. Order free CD stud samples (freight collect), run the trials with your gun settings chart, and record the successful settings as part of the process sheet.
Your next action
Write down: panel material and thickness, coating, thread and stud length, and whether the reverse face is visible. Send it via the quote form or WhatsApp – we will confirm CD suitability, part numbers and dispatch (3–7 days stock), and free samples let you qualify the process on your line.