{"id":20447,"date":"2026-06-23T10:09:42","date_gmt":"2026-06-23T10:09:42","guid":{"rendered":"https:\/\/resistance-welding.com\/?p=20447"},"modified":"2026-06-23T10:09:42","modified_gmt":"2026-06-23T10:09:42","slug":"welding-nuts-on-hot-formed-steel-which-machine-actually-works","status":"publish","type":"post","link":"https:\/\/resistance-welding.com\/ko\/welding-nuts-on-hot-formed-steel-which-machine-actually-works\/","title":{"rendered":"Welding Nuts on Hot\u2011Formed Steel \u2013 Which Machine Actually Works?"},"content":{"rendered":"

If you work in automotive stamping or body\u2011in\u2011white production, you already know the drill. A\u2011pillars, B\u2011pillars, bumper beams, rocker panels, center tunnels \u2013 these are all hot\u2011formed or ultra\u2011high\u2011strength steel these days. And almost every one of them needs some type of fastener welded on: square nuts, flange nuts, or bolts.<\/p>\n

Here is the problem. Hot\u2011formed steel has a yield strength up to 2400 MPa. It also comes with an aluminum\u2011silicon coating. Try to projection\u2011weld a nut onto that surface, and you run into trouble fast. The coating interferes with contact resistance. The high strength makes it hard to get enough local deformation. The heat wants to sink into the massive part instead of staying at the interface.<\/p>\n

\"Energy<\/p>\n

So how do you choose a welder that can handle this job reliably \u2013 without overpaying or overloading your plant’s power capacity?<\/p>\n

Let us walk through the three power supply types that are actually used for hot\u2011formed steel projection welding today, and what each one does well \u2013 and poorly.<\/p>\n

Why hot\u2011formed steel needs a “hard” welding schedule<\/p>\n

Before we compare machines, one quick point. Hot\u2011formed steel projection welding requires what we call a hard schedule: high current, high force, and short time.<\/p>\n

You cannot stretch the weld time to make up for lower current. The coating burns off quickly, and if you dwell too long, the electrode overheats, the nut sinks too deep, or the weld becomes brittle. The weld needs to happen fast \u2013 really fast \u2013 with a massive current punch and enough pressure to collapse the nut’s projections into the steel surface.<\/p>\n

With that in mind, here are the three power supply options.<\/p>\n

Option 1: Capacitive discharge (CD) \u2013 the industry default<\/p>\n

Capacitive discharge welders<\/a> are currently the most common choice for hot\u2011formed steel projection welding. If you look at the two big names in the hot\u2011forming world \u2013 a German company (let us call it B) and a Spanish company (H) \u2013 both use CD welders as their standard.<\/p>\n

Why? Because CD supplies deliver an extremely short discharge time \u2013 typically 5 to 10 milliseconds \u2013 with a peak current that can reach 50 to 150 kA. When you combine that with a large welding cylinder (often \u00d8200 mm or even \u00d8300 mm), the projections melt and forge into the hot\u2011formed sheet almost instantly.<\/p>\n

What works well:<\/p>\n