Fit for Welding

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by John Ward

Keep contact tips, cones and diffusers in top shape


Regular maintenance of your welder is one of the best ways to ensure quality welds and that the machine and consumables last as long as possible. This is important because it helps you save money in the long term and protect your investment.

Wire welders require more maintenance than other welders because they have more components to look after, such as the drive rolls, contact tips and a gas hose. We’re going to focus on how to properly maintain contact tips, cones and diffusers. These play a crucial role in providing the right gas flow and electrical conductivity from the welding gun. If they’re not maintained, you can end up with excess spatter, porosity and poor penetration. You may also need to replace parts more often. 

These guidelines on how to prevent and repair damage to your contact tip, nozzle and diffuser are designed to help you maintain a high level of welding performance and improve the lifespan of your machine. Always unplug the welding machine before performing any of the tasks described. 

Nozzle dip to prevent spatter sticking
Prevention is better than cure when looking after your welding equipment. The best way to look after your gun nozzle is by using a nozzle dip. Dipping the nozzle into this jelly-like substance will help stop spatter from sticking to it, which could hinder the gas flow from your gun and reduce weld quality. Dip only the end in or you could damage the inside of the nozzle. 

Wire stickout
Make sure you keep the right distance between your contact tip and your workpiece. If your stickout is too short or it touches the weld pool, this can cause the consumables to become damaged by overheating, burnback or wire stick. These all shorten the lifespan of your consumables and will end up costing you more money. Keep the stickout between 6.35 mm (1/4-in.) and 9.5 mm (3/8-in.) distance and don’t let the tip touch the weld pool.

Ensure the contact tip is tight
Check that your contact tip isn’t loose before you start welding. A loose contact tip will result in poor current transfer and an unstable arc. It will also result in overheating as the loose tip heats up and the diffuser can become burnt. You may also experience erratic wire feeding. Tighten up your front end consumables on a regular basis to help them last longer.

Use correct sized consumables 
You need to ensure you use the right sized nozzle and contact tip for your welding application. The nozzle diameter should increase when using higher current. If your nozzle is too small, this will prevent heat from dissipating and cause the consumables to overheat. It will also limit gas flow and could cause an increase in spatter.

If you change your wire diameter you will need to change your contact tip to match it. If your contact tip is oversized you will experience poor current transfer and overheating which can lead to burnback. If your contact tip is too small then it can cause friction and slow down the wire feed speed. It can even cause the wire to jam completely. The hole in the tip should allow for the wire to feed smoothly but not be too big to disturb current transfer.

Clean away spatter
Even if you’ve done everything you can to keep your welding gun free from spatter, its closeness to the welding pool means you’ll still need to check the consumables regularly to assess any damage and clean them if necessary. Remove the cone and use a wire brush to clean any spatter from the diffuser. The diffuser disperses the shielding gas so it needs to be kept clean or gas flow could be hindered and your welding consumables could overheat. You can also remove spatter from the nozzle with a needle nose file or MIG pliers.

Follow these guidelines and you can have more consistent quality welds and maintain your consumables for longer and save money by not having to replace them as frequently. You’ll still need to replace your welding consumables eventually, no matter how hard you try, as the constant exposure to heat makes them prone to damage and warping. But taking simple steps to stop overheating and burnback could save you a fair bit of money in the long run. SMT

John Ward is the editor at Reach him at [email protected]  

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