Contact or induction ERW welding?

There are several different ways to create steel tubing, but electric resistance welding is one of the best. It is quick, cost effective, and can provide advantages such as a small weld zone and a strong bond. Interestingly, there are a number of ways to do it too. We want to look at the different processes in terms of contact and induction welding. Then if you want to purchase ERW tube, we’d be happy to work with you.

The basics

The core of ERW is you need a combination of heat and pressure to create a forged weld. Start by heating the edges of the tube to slightly below melting point. Then apply forging force to push them together to forge a bond. The end result is a tube with only a slight bead.

What you need here is the ideal level of heat and the appropriate forging force. Too hot or too cold and you won’t get a good bond. Too little pressure and the weld will be weak. Even worse, too much pressure will force out more material and create a big bead.

Two methods of heating

ERW tubeWith ERW tube you take advantage of the electric resistance of the material to heat it efficiently. This is better than utilising other options such as a flame. There are actually two different ways to do it; contact and induction.

The first requires you to place contacts on the strip of metal. You then apply the weld power directly to them and into the material before applying the forging pressure. This is a very efficient method. It is particularly good for heavy wall tubes because of the speed.

However, there are two main drawbacks with contact welding. Firstly, because the contacts touch the metal, it can leave marks. If surface appearance is important, it may not be a good option. In addition, it takes time to set up for each weld as you need to place the contacts. If you are producing batches of tube, that can extend the overall production time.

Induction welding is an interesting alternative. What happens here is you have a work coil. You place it in front of the weld point and then send electric current through it. Heat transfers into the material thanks to the magnetic fields surrounding the tubing. You then have the forging force to push the edges together to form the ERW tube.

There are some useful advantages and one drawback here. In terms of benefits, there won’t be any contact marks. Plus, setting up is quick and you don’t need to make big changes each time, even if you change tube size. The cost for this is the technique is less efficient.

Do you want to order high quality ERW tube?

At Union Steel Tubes we use the best equipment and reliable techniques to create fantastic products. The welds will be high quality, ensuring the tubing is strong and durable. We also offer finishing techniques to remove weld beads and hide the seam. Plus, you can opt for things like galvanisation or chrome plating if you need to improve corrosion resistance and the aesthetics.

So, speak to us if you want ERW tube or have any questions. We’re happy to share our knowledge and can recommend tubing if necessary.