During the CNC machining process, there are chances of errors. They can come up in any shape. When the machinists are manufacturing high-precision parts, then there is no chance of any error developing. One such error is BUE (built-up edge).

BUE can lead to poor surface finish, increased tool wear, and decreased productivity, affecting the quality and efficiency of the manufacturing process. Understanding the causes and effects of BUE is crucial for CNC machining operators and manufacturers to develop effective strategies to mitigate the problem.

Therefore removing BUE is necessary from the machining process. In this article, we will explore the causes and effects of BUE in CNC machining, providing insights into how manufacturers can overcome this challenge to optimize their production processes.

What is BUE (built-up edge) in machining?

The accumulation of workpiece material on the tool’s rake face is known as a built-up edge (BUE). This material separates from the chip and welds under pressure. 

Many different factors can cause it, and it can impact the outcome of a precision CNC project. Too much build-up on the chip’s edge can cause the tool to separate from the chip.

The workpiece materials are deposited at the cutting edge during the turning process, resulting in the formation of a build-up edge. As a result, the deposits alter the cutting edge’s geometry, reducing the cutting edge’s ability to make clean, sharp cuts.

Rapid turning essentially combines the properties of the cutting tool and the workpiece material.

As a result, CNC machine shops and their clients must be aware of the precautions that one should take to avoid this. 

Importance of understanding the causes and effects of BUE

Understanding the causes and effects of built-up edge (BUE) is essential for improving the efficiency and quality of CNC machining operations. BUE occurs when a small amount of material adheres to the cutting tool and accumulates over time, leading to poor surface finish, increased tool wear, and decreased productivity.

Here are some reasons why it is crucial to understand the causes and effects of BUE:

Minimizing Tool Wear: By understanding the causes of BUE formation, operators and manufacturers can implement measures to reduce wear and tear on cutting tools. BUE can cause significant damage to cutting tools, leading to a shortened lifespan and increased costs. By minimizing BUE formation, the lifespan of cutting tools can be extended, reducing costs and improving overall efficiency.

Enhancing Surface Finish: BUE can cause uneven surface finish, decreasing product quality and performance. By understanding the effects of BUE, manufacturers can develop strategies to minimize its impact on surface finish. This, in turn, can improve product quality and increase customer satisfaction.

Improving Productivity: BUE can lead to a decrease in productivity due to the need for frequent tool changes and adjustments. By understanding the causes of BUE, operators can implement measures to minimize its formation, reducing the need for frequent tool changes and increasing productivity.

Increasing Profitability: By minimizing BUE formation and improving efficiency, manufacturers can reduce costs and increase profitability. This can be achieved by optimizing tool selection and implementing process control systems.

Understanding the causes and effects of built-up edge (BUE) is critical for improving the efficiency, quality, and profitability of CNC machining operations. Manufacturers can optimize their production processes by minimizing BUE formation, enhancing surface finish, increasing productivity, and reducing costs, improving overall competitiveness and success in the marketplace.

What causes the formation of BUE?

  • The geometry of the cutting tool gets altered as the material builds up. The rake angle gets included. This shift in geometry occurs regularly. As a result, the metal removal process loses dimensional control.
  • A work-hardened and abrasive material makes up a built-up edge. When pieces break free from the cutting tool, they stick to the workpiece and scratch the surface.
  • The higher the BUE, the rougher the surface will be.
  • The cut with a built-up edge is usually deeper than it would be with just the cutting instrument’s tip.
  • When a piece of the cutting tool breaks off, it can take some of the tools with it. As a result, tool wear is premature.
  • Reduce friction – If you want to use low cutting speeds, use the ideal cutting lubricant. The cutting fluid will carry away the heat generated during machining. When there is less heat, there is less build-up.


BUE effects on the cutting process

In short, too much build-up edge can lead to dimensional inaccuracies and even the complete scrapping of a part or component. 

It also results in a poor surface finish, which can drive up the cost of any machining project. For a skilled machinist, a build-up edge is one of the easiest things to spot and manage.

Problems BUE creates for CNC machine shops: 

  • Cutting tools have a short lifespan.
  • Lead times are longer.
  • Variations in component uniformity.
  • Surface finishes that are not up to par.
  • Reduced quality in part.


Ways to reduce BUE in CNC machining

1. Opt for free-cutting tools with sharp geometries and highly polished surfaces when choosing an instrument. Picking an ideal CNC tool with chip breaker geometry will aid in the division of chips, making it easier to remove them from the part and cutting surface.

2. Increase the cutting speeds, especially when using carbide inserts, because chips will have less time to adhere to the tool.

3. Be sure of your application strategy and running parameters. It is always a good idea to double-check your running parameters to ensure they are ideal for your turning application.

4. Cutting fluids can help reduce the amount of built-up edge. It accumulates on tooling components by reducing the amount of heat produced during machining.

5. Choose a coated insert because coatings get designed to prevent common machining issues. It gets engineered for a given set of part materials.

6. Select free-cutting tools with precise geometries and smooth surfaces that get meticulously maintained. Keep in mind that the geometry of the chip breaker may help to reduce chip adherence even more.


Looking for an experienced machinist who can overcome BUE in CNC machining? Contact Us! We can help. 


How Does Machine Design Associated Help to Overcome Built-up Edge Problems?

We only use best practices to ensure that our work for our customers gets done in the most efficient, precise, and cost-effective way possible, with a strong focus on continuous improvement.

Here are the reasons to choose us for your BUE that are below:

  • Quality Standards

Our expectations for the quality and performance of our products are high. We are proud of our ability to design and manufacture products and services that consistently deliver exceptional results, and we stand behind them completely.

  • Expertise

Our worker’s abilities, talents, and expertise have earned us a reputation as technical experts in the industry. We invest in and continue to develop a highly-skilled workforce eager to share their knowledge with our clients.

  • Our Machinery

We have a variation of CNC machinery at MDA, including our CNC milling machine in Canada, among other things. We keep up with the latest advancements in CNC machinery, so our equipment, such as our CNC milling machine in Canada and throughout North America, is always top-of-the-line and serviced to ensure it is running at its peak.

  • Selection of Cutting Tools 

MDA’s machine design team selects cutting tools based on their geometry, material, and coating. Cutting tool geometry plays a crucial role in preventing BUE. By selecting the proper geometry and rake angle, the cutting tool can reduce the tendency of the material to adhere to its surface, thereby reducing the formation of BUE.



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