Aug 24, 2017

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Metal Machining – Built Up Edge Issues

Metal Machining – Built Up Edge Issues

With metal machining, a deposit can form on your cutting tool’s rake face. This is called built up edge or BUE. It can be a problem for some shops, but BUE can have both positive and negative effects on your work. Let’s take a closer look at this issue to explore some solutions.

What is BUE?

When you machine metal, it creates a lot of friction that leads to heat. In fact, the heat can be substantial enough to cause the metal surfaces to work harder. Buildup is the greatest on cutting tool surfaces because that’s where the shear force is its strongest. This layer may get as thick as a few hundred micrometers.

What Causes BUE?

At high cutting speeds, BUE doesn’t usually occur because the metal moves away from the cutting tools too quickly for buildup to occur. However, at slow metal machining speeds, this is not the case. Also, the kind of metal that you machine makes a difference because alloys are more prone to BUE than pure materials.

Positive Effects of BUE

If you use additives to limit built up edge, it can create a stable coating that’s thin. For example, manganese sulfide helps to keep heat buildup to a minimum, and when working with some steel metals, BUE is not an issue. You can receive these benefits from built up edge:

Longer cutting tool life
Improved surface finishes
Less power needed

Negative Issues with BUE

With some metals, BUE can wear cutting tools faster and give you a poor finish. This can cause shop downtime issues.


Increase carbide cutting speeds.

Decrease HSS cutting speeds. With high-speed steel cutting tools, slower speed can actually limit heat buildup.

Use high-quality metal machining coolants.

Change the rake angle of the cutting tool. A sharper angle can limit BUE.


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