Welding: material preparation matters

Talk to successful welders, welding equipment and accessory firms, and professional bodies and you’ll hear one consistent message. You may be an experienced or a novice welder. You could be doing DIY welding or fabricating at the highest level. Either way, material preparation is one of the keys to successful welding. Here are some things to consider…

Old paint, rust, oil, water and other work-piece contaminants are all potential weld killers. Alone or together, left on a work-piece, they lead to lost time, wasted money, poor job satisfaction, damaged reputations and potentially dangerous welds.

At its simplest, the top-level advice on welding-material preparation is that you mustn’t cut corners and that cleanliness is vital. Time spent on thorough preparation is never wasted. And, by the way, wherever possible, clean new metal beats re-used material every time.

Material preparation for different welding processes

What about material prep for different processes? Seasoned welders such as R-Tech’s Mike Gadsby know that, while good preparation is essential, different welding processes bring their own special demands.

Manual metal arc welding (MMA) may be more forgiving than MIG or TIG welding, as is any form of gasless welding. That’s because these processes tend to run hotter and burn contaminants away – but don’t count on this alone.

Always prepare thoroughly and appropriately for the welding you’re doing – whether it’s agricultural MMA work or the most precise fabrication using TIG welding. By the way, if your welding project demands TIG, you’ll find that this process is super-reliant on clean metal. If ever new, unoxidised metal will reward you it’s when you’re TIG welding.

Of course, whatever material you weld with, make sure to clean the reverse of the work-piece too. Clean deep into the hidden depths of any cracks as well (especially in cast iron). And consider the merits of a final chemical wipe such as acetone to remove last traces of the oily contaminants that will undermine even the best welder’s technique.

The challenge of different metals

Because of its widespread use for machinery, cast iron is notoriously prone to contamination. This is often made worse by the age of components or their long exposure to the elements in agricultural or vehicle engineering.

Even relatively new aluminium will quickly get an oxide coating. This must be removed with stainless steel wire brushing. And if you’re working with stainless steel (aka inox steel), make sure your cleaning tools, including abrasive wheels, are suitable for this metal. Matching tools to metal is critical to avoid the effects of poor material preparation. We’ll look at some of the most common welding defects – and how to avoid them – next week.

The professional’s view

Recalling material preparation challenges he’s encountered over the years, Mike Gadsby highlights the special demands of high-tensile and other difficult-to-weld steels:

‘With specialised stainless and tool steels, careful pre-heating (which can be in excess of 300 °C) is an important part of material preparation before you start welding. Make sure you allow the work-piece to cool slowly as well. It’s like letting a Sunday roast ‘rest’ after it comes out of the oven. It takes a bit of time but the result is always better for making the effort!’

One takeaway about material preparation

Do you ever watch TV series such as Fast n’ Loud? If so, you’ll notice how thoroughly they prepare vehicles during conversion and rebuilding. Okay, so you may not be prepping a complete Shelby Mustang chassis for paint. But even if you’re only making a small DIY chassis repair, it really is worth the time and effort it takes to remove all that old paint and underseal before welding.

If you remember only one thing from this article it’s that material preparation really matters before you start welding. It’s vital, regardless of the welding process or the materials you’re welding. There are no shortcuts.

Do your research, ask trusted welding colleagues, and check out videos from sources such as this website before doing that oh-so-important preparation.

Any questions? Speak to an expert

Still got a question about material preparation for your welding project? The R-Tech team know welding and welding equipment inside out. We are always willing to help with valuable objective advice about products and techniques to suit your welding process and choice of metal.

Send us an email or call us sometime!