Blog - Heavy steel cutting: use oxy-fuel or plasma?

By
Jan Kranendonk
– Updated
Jan 13, 2016

In this blog post, we will discuss two common robotic cutting processes for heavy steel and their respective benefits: oxy-fuel cutting (OFC) and plasma cutting.

Oxy-fuel or plasma cutting

Cutting of heavy steel profiles

Cutting of heavy steel profiles is a key process in various industries, for example in shipbuilding, offshore construction and structural steel. Fabricators are dealing with a large variety of profiles, such as H-beams, tubes, flat strips, T-bars, bulb profiles and square tubes. While all profile types have their respective challenges, it all starts with the choice: which cutting process should you use? 

To be clear: this is about robotic cutting. That means we skip sawing lines, which are not able to make a 3D shape to your profile. Two cutting processes are suitable for 3D shapes: oxy-fuel cutting (OFC) and plasma cutting.

Oxy-fuel cutting

With OFC (‘flame cutting’), a torch with a fueling gas (e.g. acetylene) is used to preheat the metal. At a certain temperature, oxygen is added to pierce through the material. The robot then moves the cutting torch at a continuous speed, which gives extremely accurate cuts. The small size of the cutting torch helps to reach into corners. The steel will look like it is cut with a saw: very sharp and smooth.

Oxy fuel cutting by KRANENDONK

Apart from precision, oxy-fuel cutting is very useful for thick materials and for cutting bevels. Furthermore, the process is energy efficient, meaning that operational costs are rather low. OFC is a fairly safe method and can be conducted without the need for a protective cabin. This process only works for cutting metal, not aluminum or stainless steel.

Benefits of oxy-fuel cutting:

  • Extremely accurate
  • Small torch that can reach small spots
  • Possibility to cut very thick materials
  • Low operational costs (one-tenth of plasma cutting costs)

Plasma cutting

Plasma cutting is a very powerful process for high speed cutting and is typically twice as fast (or more) as oxy-fuel cutting. Plasma is the ‘fourth state’ of matter. It can be seen everyday in lightning, electric sparks and neon lights. The torch blows gas out of a nozzle at high speed, while an electric arc turns this gas into plasma.

Plasma cutting by KRANENDONK

The plasma process is common in cutting of steel plates, so robotic plasma cutting works very well on materials up to 40 mm in thickness. Cutting speeds will be lower on heavy steel profiles. The speed of the process is a great benefit, but it has one downside: the immense power of the process puts a lot of pressure on consumables (nozzles) and shop floor safety (fumes, light and noise). This results in higher operational costs than OFC cutting.

Benefits of plasma cutting:

  • Very high cutting speed
  • High productivity
  • Also suitable for aluminum and stainless steel

Conclusion

The right process depends on the application (beam cuttingtube cutting or flat profiles) and the intended productivity of the machine. You can save on your operational costs and make extremely accurate cuts by using OFC, or go for maximum productivity with plasma.

For more information, we are glad to advice you (contact us).