What tolerances can you expect from every profile cutting method?

Understanding steel tolerances can be challenging, but they play a crucial role in ensuring parts fit correctly, function reliably and remain interchangeable. Incorrect steel tolerances can lead to costly errors, delays and unnecessary material waste.

In this article, we explain what steel tolerance actually is, the factors that influence steel tolerances and the typical tolerances you can expect from the four main steel cutting methods.

What does tolerance actually mean in steel profile cutting?

In steel cutting, tolerance refers to the acceptable variation between the designed dimension and the finished component.

For example, a ±0.5 mm tolerance means the part can be 0.5 mm larger or smaller than specified. Tighter tolerances require more control, slower cutting speeds and higher process stability.

Key factors that influence steel tolerances

Steel cutting tolerances are not fixed values. They are the result of several interacting factors, all of which influence how closely a finished part matches the original design.

Cutting method: Each process controls energy and kerf width differently, directly influencing how accurately steel can be cut.

Material thickness: Thicker steel increases beam spread, heat influence and edge taper, which naturally widens achievable tolerances.

Heat input and thermal distortion: Thermal cutting causes expansion and contraction that can move material during cutting and affect final dimensions.

Machine quality and calibration: Rigid, well-maintained CNC machines hold tighter tolerances than worn or poorly calibrated systems.

Programming and cut strategy: Cut order, lead-ins and nesting layout determine how heat is distributed and how stable the material remains.

What tolerance can you expect from plasma cutting?

±0.5 mm to ±1.0 mm, depending on thickness and edge requirements.

Why plasma cutting tolerance varies?

Plasma cutting uses an electrically charged gas to melt and eject material. While modern HD plasma systems are highly advanced, plasma is still a thermal process, meaning heat affects accuracy as thickness increases.

Typical plasma cutting tolerances by thickness

What tolerance can you expect from laser cutting?

±0.1 mm to ±0.3 mm, but only on thinner material.

Why laser cutting is more accurate?

Laser cutting uses a highly focused beam of light, producing:

• A very narrow kerf

• Minimal heat affected zone

• Excellent edge definition

However, laser accuracy decreases as thickness increases due to beam dispersion and power limits.

Typical laser cutting tolerances by thickness

What tolerance can you expect from flame cutting?

±1.5 mm to ±3.0 mm, depending on thickness.

Why flame cutting has wider tolerances?

Flame cutting relies on oxygen and fuel gas to oxidise and remove material. This introduces:

• A wide heat affected zone

• Greater thermal distortion

• Less control over kerf width

Despite this, flame cutting remains highly effective for very thick steel.

Typical flame cutting tolerances by thickness

 

 

Conclusion

Different steel cutting methods offer different tolerances based on their capabilities. Laser cutting achieves very tight tolerances but is best suited to thinner materials. Plasma and flame cutting operate with wider tolerances but are far better suited to thicker plate steel. The most appropriate tolerance will always depend on the application, material thickness and end use of the component.

If you have any questions about specific steel tolerances, please get in touch with our team at RMP. We work closely with our customers to explain how each cutting method is matched to different tolerance requirements, ensuring the best possible results for every profile cutting project.