An unstable arc, difficulty starting the arc, incorrect shielding gas flow and inconsistent welds usually share a small set of causes: incorrect machine settings, contaminated material, worn torch consumables, poor electrical connections and gas-supply faults. Checking the machine settings, the work return clamp, consumable condition and the complete gas system — and following approved procedures — restores a stable, repeatable arc.
This guide covers arc stability, arc starting, shielding gas flow, how much gas to use, and why welds come out inconsistent.
Why is my welding arc unstable?
An unstable arc may be caused by incorrect voltage, inconsistent wire feed, contaminated material, worn torch consumables or poor electrical connections.
Check machine settings, inspect consumables and ensure the work return clamp provides a good electrical connection.
Why won’t my welding arc start?
Difficulty starting the arc may result from poor earth connections, contaminated material, incorrect polarity, damaged consumables or incorrect machine settings.
Inspect the welding circuit, clean the workpiece and replace worn consumables before troubleshooting more complex issues.
Why is my shielding gas flow incorrect?
Incorrect gas flow may result from regulator faults, leaking hoses, blocked nozzles or incorrect flow settings. Too little gas allows atmospheric contamination, while excessive flow may create turbulence and reduce shielding effectiveness.
Check the complete gas system before welding.
How much shielding gas should I use?
The correct shielding gas flow depends on the welding process, nozzle size and working environment. Excessively low flow can cause porosity, while excessively high flow may introduce turbulence.
Always follow the shielding gas recommendations provided for your welding process and consumables, adjusting where necessary for draughty environments. For gas selection by process, see our shielding gas comparisons.
Why are my welds inconsistent?
Inconsistent welds are often caused by variations in welding technique, machine settings, consumable quality or material preparation. Maintaining consistent travel speed, stick-out and torch angle, using quality welding consumables and following approved welding procedures all contribute to more repeatable weld quality.
Regular maintenance of welding equipment and operator training also help achieve consistently high standards.
Stable arcs start with sound connections and quality consumables
Arc instability, hard starting and inconsistent welds nearly always come back to the same fundamentals: correct settings, a good earth and work return connection, clean material and consumables in good condition. Quality consumables — wire, contact tips, gas — produce a more stable arc and more repeatable results, reducing rework.
Explore our welding consumables guide or contact the Weldability SIF technical team for advice on getting a stable, consistent arc.