What's inside
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What the pulse function does
On a TIG welder, pulse switches the output between a higher peak current and a lower background current. The peak helps form the puddle; the background keeps the arc going while letting the weld cool slightly. That can make it easier to control heat on thin sheet, reduce burn-through, and keep a small, consistent bead.
Pulse does not eliminate heat input. If travel is slow, the sheet is dirty, the fit-up has gaps, or the current is too high, you can still warp or burn through it. Think of pulse as one way to manage heat and puddle rhythm—not a substitute for good fit-up and steady movement.
Set up the machine and joint first
Use clean, tightly fitted material. Remove paint, oil, rust, and mill scale from the weld area, and deburr the edges. A gap that looks small on a bench can open as the sheet heats; on thin material, that may turn a manageable weld into a hole. Clamp the parts to a flat backing bar or copper chill bar where practical. Tack the joint at short intervals before welding it out.
Choose a sharp tungsten and a cup that lets you see the joint. For thin steel, a small diameter tungsten is often easier to control at low current; for aluminum, follow the machine and electrode guidance for AC TIG. Use the correct polarity and shielding gas for the material. If you’re still choosing equipment, compare AC/DC TIG welders with pulse controls by their minimum stable output, pulse adjustability, and torch ergonomics—not just maximum amperage.
A practical starting point
Start with a modest pulse rather than the fastest setting available. For thin sheet, a useful trial range is about 1–2 pulses per second, with peak current around 1.5 to 2 times the background current. For example, try 40 A peak and 20–25 A background on a scrap coupon, then adjust to suit the joint and your travel speed. These are starting points, not universal settings: alloy, thickness, joint design, tungsten, and machine behavior all matter.
Set peak time—the share of each cycle spent at peak—around 30–50% to begin. A longer peak time adds heat and gives the puddle more time to form; a shorter one cools the weld more between peaks but can make the puddle harder to establish. Many machines label this setting “pulse width” or “duty cycle.” Check the manual, since terminology and adjustment ranges vary.
If your welder has background current but no separate peak-time control, use what it offers and tune by testing. Make a short bead on scrap of the same material and thickness. Watch whether the puddle forms cleanly, whether the sheet distorts, and whether the bead ties into both edges. Change one setting at a time so you can tell what helped.
How the controls change the weld
| Control | What you’ll notice | If set too high or too low |
|---|---|---|
| Peak current | How quickly the puddle forms | Too high can cause burn-through or undercut; too low can leave poor fusion |
| Background current | How well the arc stays active between peaks | Too high adds heat and distortion; too low can make the arc unstable |
| Pulse frequency | How fast the current alternates | Low rates make each heat cycle more noticeable; high rates may feel like a steadier arc and can be harder to read |
| Peak time | How long each cycle stays at peak | Too long raises heat input; too short may not make a usable puddle |
Use a steady rhythm at the torch
Hold a short, consistent arc—roughly 1–2 mm is a useful target—and keep the torch angle modest, often about 10–15 degrees from vertical. Add filler at the leading edge of the puddle, then move forward as the puddle forms. With a slow pulse, some welders time filler additions to the peak; others feed filler continuously. Either approach can work. Choose one that produces consistent bead width and fusion, rather than forcing your hands to follow a rhythm that feels awkward.
Keep moving. A pulsed setting may let you see the puddle expand and contract, but pausing on each pulse can build excessive heat. If the sheet starts to sag, the bead spreads wider, or the color and distortion increase, move faster or reduce peak current or peak time. If the bead sits on top without tying into the edges, check your fit-up and technique before simply raising current.
Troubleshoot by changing one thing
Burn-through: Check for gaps and slow travel first. Then lower peak current, shorten peak time, or increase travel speed. A lower background current can also reduce total heat, but don’t drop it so far that the arc becomes erratic.
Cold lap or poor fusion: The peak may be too low or too brief, or the arc may be too long. Raise peak current slightly, increase peak time, shorten the arc, or slow down just enough for the puddle to wet both edges. Inspect the back of a test weld where possible.
Excessive distortion: Use short weld segments and alternate locations rather than completing one long seam in one pass. Clamp the work, allow it to cool between sections, and consider a chill bar. Pulse can help, but sequence and restraint often matter more.
Uneven bead: Check hand travel and filler timing. A low pulse rate can provide a visible rhythm, but it won’t correct inconsistent movement. If the pulsing makes it harder to maintain a steady bead, try a higher frequency or switch pulse off.
When pulse is worth using
Pulse is most useful when a thin part is sensitive to heat, when you need repeatable short welds, or when a controlled puddle helps you work around a joint. It can also make a welder more comfortable on sheet, but results depend on operator technique and machine controls. On very thin sheet with a tight fit-up, a simple steady-current setup may be easier and cheaper. If you’re assembling a TIG kit, a reliable torch and the right filler metal may matter more than extra pulse features; compare TIG torch consumables and filler matched to your material before paying more for advanced controls.
Use scrap of the same thickness to find settings before welding the actual part. Record peak current, background current, frequency, and peak time along with travel speed and joint details. That gives you a repeatable starting point—and a clear way to tell whether pulse is helping or just adding another control to manage.