What is Oxy-Fuel Cutting?

Oxy-fuel gas cutting is a widely used thermal cutting process that combines oxygen and a fuel gas, typically acetylene, propane, or natural gas, to create a high-temperature flame. This intense heat is directed onto a metal workpiece to sever or shape it. Due to its versatility and cost-effectiveness, the process is commonly utilized in various industries, including metal fabrication, construction, and automotive repair.

On Zoned extraction KUTAVAR CNC machines we offer an oxy-fuel gas cutting torch as an optional extra. This allows a greatly increased cutting range compared to conventional plasma when cutting material such as mild steel.

Some KUTAVAR customers opt for a combined CNC plasma and oxy-fuel cutting system. However, we also provide a standalone CNC gas-cutting machine.

Not sure if Oxy-fuel is right for your needs? Continue reading below as we highlight some advantages and disadvantages of Oxy-fuel gas cutting.

Cutting Thick Materials

KUTAVAR allows for the clean cutting of material up to 100 mm thick with our CNC Oxy-fuel gas cutting torch. We raise our gantry clearance by an additional 120mm to allow such thick materials to be cut safely.

We still use the same 5-axis machined 5038 Aluminium tooling plate, for our gantry which guarantees the same micron tolerances, just on a larger scale.

Oxy-fuel offers the flexibility to cut thick material, cleanly and efficiently at a much lower cost than a High-definition plasma power source needed to cut material of the same thickness.

Fuel Gas

KUTAVAR uses an Oxy-propane mix for our CNC gas cutting. Compared with oxy-acetylene there are a few noticeable differences.
 
Oxy-acetylene generates a significantly hotter flame compared to oxy-propane. Comparatively, oxy-propane burns at a lower temperature, and lowering the heat input reduces the Heat Affected Zone (HAZ) in the cut material, minimizing distortion.

Oxy-propane produces a softer flame, which often results in a cleaner and smoother cut up to 100 mm.
 
Propane is considered safer than acetylene due to its wider flammability range, which reduces the risk of accidental ignition.
 
Propane is generally more cost-effective than acetylene, which can be significant for large-scale cutting projects.

 

Cutting Speeds

For the sake of our comparison, we’ll compare the KUTAVAR oxy-fuel torch to a Hypertherm Powermax 105 SYNC cutting mild steel of various thicknesses.

The Powermax 105 Sync will cleanly cut mild steel up to 22 mm thick at approximately 790 mm/min. Whereas the oxy-fuel gas torch will cut the same material at 510 mm/min (35.4% of the speed of plasma)

As such, for all materials within the clean-cutting range of the Hypertherm Powermax 105 SYNC, we would recommend using it over the oxy-fuel torch. Not only for the higher speed of cutting and greater productivity but the cut itself will be cleaner with fewer deposits of dross, ultimately reducing any post-cut cleanup.

Oxy-fuel starts to outperform the 105 SYNC at thicknesses greater than 30 mm.

As the plasma source would need an edge start to cut mild steel this thick, the quality of the cut would suffer immensely. Considerably more dross would form on the underside of the plate, a much larger Heat Affected Zone (HAZ), lower consumable life, and slower cutting speeds – 380 mm/min. 

Oxy-fuel will cut the same material at 440 mm/min (15.8% faster). This becomes even more pronounced the thicker the material. At 40 mm Oxy-fuel will cut twice as quickly as a Hypertherm Powermax 105 SYNC! (400 mm/min vs. 200 mm/min)

See how well a KUTAVAR cuts 50 mm mild steel with a CNC oxy-propane gas cutting torch.

Accessibility

Due to the relatively basic requirements of Oxy-fuel cutting, it becomes an ideal choice for those in rural and remote settings, e.g. farmers. The lack of need for a three-phase electricity supply, or suitable air compressor that a plasma power source demands, makes CNC oxy-fuel gas cutting a popular choice within the agricultural engineering sector.

In conclusion, while the cutting speed of the oxy-fuel torch is slower compared to plasma on thinner material, it excels in cutting thicker materials, where plasma cutting would suffer from lower quality, dross formation, and a larger Heat Affected Zone. As a result, it is the preferred choice for such applications, ensuring efficient and clean cuts.

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