Running a bead weld along a flat steel plate is one of the most fundamental welding skills you can learn. With the right setup, machine settings, and technique, even a beginner can lay a tidy, consistent bead. Here's how to do it safely and correctly.
What You'll Need
Before you strike an arc, gather your equipment:
- Welder – A MIG (GMAW) welder is the most beginner-friendly option for flat plate work. A stick (SMAW) welder also works well and is common on NZ job sites.
- Steel plate – Start with mild steel, ideally 3–6 mm thick. Thinner plate is harder to control without burning through.
- Consumables – MIG wire (commonly 0.8 mm ER70S-6 for mild steel) or stick electrodes (e.g. 2.5 mm E6013 for beginners).
- Angle grinder – For cleaning and preparing the surface.
- Wire brush and chipping hammer – For cleaning slag (stick welding).
- PPE – Auto-darkening welding helmet (shade 9–13 depending on process and amperage), leather welding gloves, long-sleeved cotton or leather jacket, closed-toe leather boots, and ear protection.
Safety First
Welding produces UV radiation, intense heat, fumes, and spatter — all of which can cause serious injury. Always weld in a well-ventilated area or use local exhaust ventilation to avoid inhaling fumes. Never weld near flammable materials, LPG cylinders, or fuel. Keep a fire extinguisher close by.
For guidance on welding hazards in NZ, refer to WorkSafe NZ, which publishes practical guidance on hazardous substances and safe work practices.
Preparing the Steel Plate
Good preparation is half the job:
- Clean the surface – Use an angle grinder or wire brush to remove mill scale, rust, paint, and oil. Contaminants cause porosity and weak welds.
- Secure the plate – Clamp it firmly to a welding table or solid workbench so it won't move.
- Mark a straight line – Use soapstone or a scriber to mark a straight line across the plate. This gives you a visual guide to follow.
Setting Up Your Welder
Settings vary by machine, process, and plate thickness. As a general starting guide for MIG welding mild steel:
| Plate Thickness | Wire Diameter | Voltage (approx.) | Wire Speed (approx.) |
|---|---|---|---|
| 3 mm | 0.8 mm | 17–19 V | Medium |
| 5 mm | 0.8–0.9 mm | 19–21 V | Medium-high |
| 6 mm | 0.9 mm | 20–22 V | High |
These are approximate starting points only — always refer to your welder's manual and run test beads on scrap first.
For stick welding with a 2.5 mm E6013 electrode, a starting amperage of around 70–90 A is typical for 3–5 mm plate, but again, check your electrode manufacturer's data sheet.
Running the Bead — Step by Step
1. Position Yourself Correctly
Sit or stand comfortably so you can move your hand smoothly along the full length of the plate without stopping. Rest your forearm on the bench if possible to steady your movement.
2. Set Your Travel Angle
For flat position welding, hold the torch or electrode at a travel angle of 5–15° in the direction of travel (a slight push or drag angle). For MIG, a slight push angle (pointing forward) is common. For stick, a drag angle (pointing back toward the completed weld) is standard.
3. Maintain Consistent Contact-Tip-to-Work Distance (MIG)
Keep the MIG torch nozzle approximately 10–15 mm from the plate. Too far and you lose shielding gas coverage; too close and you risk spatter buildup in the nozzle.
4. Strike the Arc and Start Moving
- MIG: Pull the trigger and begin moving immediately along your marked line at a steady pace.
- Stick: Scratch or tap the electrode to strike the arc, then maintain a short arc length (roughly equal to the electrode diameter).
5. Travel Speed
Travel speed is one of the most critical variables. Move too fast and the bead will be narrow and lack fusion. Move too slow and you'll pile up excess metal or burn through. Aim for a bead width of roughly 2–3 times the wire or electrode diameter. Watch the weld pool, not the arc — the pool tells you what's happening.
6. Weave or Stringer?
For a practice bead on flat plate, run a stringer bead (straight line, no side-to-side motion). This builds consistency before you attempt weave patterns.
Reading Your Bead
Once the bead cools (don't touch it — hot steel looks the same as cold steel), inspect it:
- Good bead: Uniform width and height, smooth ripples, good tie-in at the edges, no holes or cracks.
- Too fast: Narrow, ropy bead with poor fusion.
- Too slow: Wide, flat, or burnt-through bead.
- Too much voltage/wire speed: Excessive spatter, convex bead.
- Porosity (holes): Usually caused by contamination or loss of shielding gas — check your surface prep and gas flow rate.
Keep practising on scrap until your beads are consistent before moving on to joints or structural work.
When to Call a Professional
DIY bead welding on non-structural steel (e.g. garden art, brackets, frames) is generally fine for a competent homeowner with the right equipment. However, structural welding — including anything that forms part of a building, trailer, vehicle chassis, lifting equipment, or pressure vessel — must be carried out by a qualified and certified welder. In NZ, structural welding is governed by standards such as NZS 3404 (steel structures) and work on buildings may require a building consent and involvement of a Licensed Building Practitioner (LBP).
If you're unsure whether your project requires certified welding or a consent, check with your local council and visit MBIE Building Performance for guidance. You can find qualified local welders and fabricators on tradedirectory.co.nz.
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