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When handling any metal processing, there are possibilities of burrs. In most cases, burrs are not wanted sections.
They may require removal. However, this is only possible if you know the types of burrs you are dealing with.
Let’s explore the different types of burrs in metal fabrication.
What are Burrs?
These are small pieces of material or raised edges created by machining operations such as cutting, engraving, shearing, compression, and bending of materials.
It’s usually an unwanted piece of material that remains attached to the workpiece after the modification process and it is common on softer and pliable materials.
BurrsTypes of Burrs
There are many types of burrs you will encounter during the parts fabrication process. These types of burrs is as a result of different machining methods and processes used during the modification and other factors such as;
- Material properties of the workpiece
- Tool cutting path
- Use of coolants among others.
1. Roll-over Burr
This is the most common type of burr encountered and it is formed when a cutting tool exits a material.
During the machining process, the sharp tip of the tool pushes/pierces through the material causing the material to roll over the edge instead of shearing off. This will end up creating pieces that are bent from the cutter’s path.
The use of improperly configured or dull cutting tools can result in its formation.
2. Poisson Burr
These are majorly burrs that result from the ‘’Poisson effect’’, which involves the outward bulging of the machined material due to shearing and compressive forces when the tool is applied to the workpiece.
When compressive forces are exerted onto the material, this leads to the deformation and elongation of the edge of the material thereby creating burrs.
3. Thermal Burrs
This is a type of burr that is majorly heat-induced.
It results from exposure of the workpiece to intense heat during the machining process, resulting in vaporization or melting of the material.
They are commonly referred to as spatter, dross, or slags and it is common in thermal machining processes such as plasma cutting, laser cutting, or electrical discharge machining.
Formation of these burrs can result in deformation of the workpiece due to rapid heating and cooling of the material and also a reduction in the material strength during the thermal machining process.
This type of burr can be removed using manual power brushing or grinding in some cases.
4. Cut-off Burrs
It is formed when a small piece of material or the cut part falls off from the main material, tearing it and leaving behind a burr.
Cut-off burrs, also known as break-off burrs occur when machining brittle materials and it can be prevented by supporting both sides of the materials properly during the cutting process.
Other possible solutions to minimize cut-off burrs, is through optimizing the cutting speed, tool geometries, and feeds.
Additionally, the use of coolant can also help in minimizing or managing heat on brittle materials, therefore, reducing the likelihood of breakage of such materials.
5. Tear Burrs
It is mostly observed during drilling or punching processes.
A tear burr is formed when a portion of the material is plastically deformed or torn away from the workpiece rather than shearing off.
Types of burrs photo credits SUGINOThese burrs are common along the edges of the machined surfaces and mostly in materials that are difficult to machine.
Conclusion
To reduce the possibilities of burrs and to produce high-quality machined components, a comprehensive understanding of these types burrs and the implementation of effective control strategies should be put in place.
