TIPS & TRICKS
‘TIPS & TRICKS’ ON HOW TO BEST MINIMISE SILICON ISLANDS
T
he experts at Lincoln Electric help us with a ‘Question from the market’: The
formation of Silicon Islands when MAG-welding causes costly extra work. Can you give us some tips & tricks on how to minimise this? The answer, from a welding engineer: The formation of Silicon Islands during MAG welding, with a wire electrode (135, active gas metal arc welding) is always undesirable. The arc may become unstable due to the low electrical conductivity of the silicon oxides however, often the main reason for this instability is due to the weld joint having to be cleaned before painting, to avoid future corrosion attacks. There are also many who have experienced problems when restarting robotic welding, due to silicon islands. The main influencing parameter is
how oxidizing the shielding gas is, in other words, a lower content of CO2 results in a smaller amount of silicon islands. The setting parameter arc Voltage affects the arc length and therefore, will influence the actual oxidation time in the welding process.
Shorter arc length generally results in shorter oxidation time, which results in a smaller quantity of silicon islands. Another parameter that can affect this is an increased content of alloying elements, (except Ti) in steel and in the weld metal. The main effect has the composition of the weld metal, but the composition of the base material also has a small influence.
These images show a typical Carbon Steel weld
Silicon Islands along the middle of the weld length
Tips for minimising the content of Silicon Islands: • Choose a consumable that provides an optimised chemical composition to provide minimal silicon islands, for example the SUPRAMIG HD wire from Lincoln Electric
• Wherever possible, use a high-quality base material
• Select a shielding gas with minimal CO2 content, without jeopardizing the stability and penetration of the welding process
Without Silicon Islands along the weld length
With Silicon Islands in the toe of the weld length
Without Silicon Islands in the toe of the weld length
• Select a waveform that provides high productivity while using a short arc length. Of course, material thickness and other factors will affect this choice, however, the Power Wave system from Lincoln Electric contains waveforms, such as Rapid X and RapidArc while also powering the patented and licensed, twin-wire MIG solution, HyperFill that is designed to perform specifically with select Lincoln Electric welding wire and is suitable for most applications and thicknesses.
www.lincolnelectric.com 16 / WELDING WORLD MAGAZINE - ISSUE 05 - SEPTEMBER 2024
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