A Complete Introduction to Deburring

deburring
– Smoothening Out Your Final Product to Achieve Maximum Machining Efficiency

An extra and useless raised edge or small piece of material that remains attached to a workpiece during a CNC machining process and can cause a potential source of machining error. These errors will disturb the beauty, smoothness, and finally quality of the parts. Since these imperfections may lead to machining accuracy reduction. That will surely affect the processing efficiency of the final product.

So, how we can get rid of these undesired pieces of metal to maximize machining efficiency and product quality? Here comes the deburring process that will introduce shine to the product and bring back its smoothness. Before we jump into the deburring process, we first understand, what is burr? What are the main causes of burr?

In this article, we will elaborate on necessary details about burring, its different types, and how it affects machining efficiency. After that, we will introduce you to the causes of burring and then some important deburring methods will be discussed. We hope, at the end of this article, you will be able to learn how to reduce the burring. Most important of all, you can decide which deburring method will suit you best according to the type of burring.

What is Burr?

During a CNC machining process, the unwanted formation of unnecessary rough edges or ridges on the surface of the workpiece is termed burr. These undesired and useless pieces of metal distort the smooth surface of the part and can harmfully disturb the product quality.

To perfectly manufacture a high-precision CNC machining part, a workpiece has to face different processes and tools. When we will be applying a process and if it is not accurately applied then it may result in small undesired rough edges or ridges on the surface of the workpiece. Such as, when we have to process a part to convert it into our desired shape then we apply stamping and milling. But, sometimes incorrect application of these processes will introduce burr to the workpiece.

Types of Burr

There are four types of burr. Any type can be produced during the manufacturing process. Burring a workpiece depends on, how it is being machined. All four types are discussed below

  • Poisson Burr

            A burr that results when a downward force is being applied on the workpiece and its material bulges outwards. This type of burr is termed as poisson burr. Poisson burr may also occur on the workpiece edges when a machining tool removes a layer from its surface laterally.

  • Roll Over Burr

            This type of burr occurs when a cutting tool exits a material during subtracting the workpiece. The reason being, tool’s sharp tip pushes the material rather than cutting through or chipping it and this results in the roll over burring.

  • Tear Burr

            Tear burr is generated during punching or drilling processes. The material gets torn away from a workpiece, rather than being sheared.

  • Cut Off Burr

            When a small slice of the material falls away from the main workpiece during the process and it gets torn up and results in cut off burr.

How Burr Affects Machining Efficiency?

Imagine working hours to manufacture a product. When it comes to delivery but your CNC services buyer finds out something unsmooth on his product’s surface. Then what? Nothing will happen. He will just complain about the product’s quality and it will leave a bad impression on him. He will not consider you a professional services provider and will harm your market reputation as well.

If the burr is not removed properly then its rough edges may interfere with the fitting or movement of parts. Removing burrs aesthetically will be help to improve the finished product.

If the burr is not dealt seriously then it can harm more than your company name and repute. Just think, the product that you claim to be efficient and high precision but it has burr. And it will be used in some very critical machines that need zero tolerance for burr. Then using a burred part can be very disastrous.

Causes of Burring During the Machining Process

The main causes of the occurrence of the burr lie basically in the manufacturing process and the tools involved in the production. Don’t worry, generating the burrs in machining processes is a normal thing and it can occur at any phase of the process.

It means burr cause during machining and cutting processes. Therefore, we mention them below separately and there are possibilities that when a workpiece will encounter any of the following processes then it may result in burring.

Machining process which may cause burr on surface of the workpiece are drilling, engraving, milling, and turning. And the cutting processes that can cause burrs on the workpiece surface include blanking, punching, laser, and plasma cutting, and shearing.

Few more factors can contribute to the burring occurrence and are discussed below

  • Operator’s Machining Experience

            The occurrence of burrs does not depend on the process only but it is very closely related to the machining expertise and skills of the operator. If the operator has masterly CNC machining skills and experience then you may not find any burrs. The final product may not need any deburring. But if the operator is at a beginner level, then the parts manufactured by him necessary need deburring and he can produce low-quality products. It will make a huge difference whether your operator is a seasoned operator or a novice.

  • Material Quality

            The quality of the workpiece material is also a great influencing factor. If you are working with a high-quality material then no burr or minor burr may generate during the process. But if the material quality is poor then you must work very carefully and be ready for performing the deburring process to maintain product quality.

Deburring Methods

The process of removing the small imperfections from the surface of the part is known as deburring. There are different methods that we can utilize to remove the burrs from the surface of the workpiece to enhance the product’s beauty. These methods are given below

  • Manual Deburring

            Manual deburring is a common and easily executed deburring process because it is the most flexible process. It is used where we have to deburr small part. This method is preferable because it requires low-cost tools and offers immediate part inspection. Tools required to execute it include scrapers, files, sandpaper, stones, and reamers, or some handheld power tools such as abrasive points, sandpaper, or cutters.

But a skilled person is required to perform the process otherwise the operator can get hurt or part may damage. Besides, this type of deburring is only suitable for small quantity with small burrs or simple structures. While for mass production, the cost is too big and not recommended.

  • Electrochemical Deburring

            In electrochemical deburring, we make the use of electrochemical machining to remove extra pieces of metal or edges that are difficult to reach like intersecting holes. The burr is dissolved by using a salt or glycol solution and electricity. Electric current is being applied to reach difficult burr locations and it is applied with the help of a specialized tool. This method takes only 5-10 seconds to get rid of the burrs and offers high precision in difficult areas.  

        Besides, this type of deburring can work on several times at the same time, and quite suitable for those difficult areas with high precision. And the problem is that it’s not workable for the large pieces, and it also requires custom tools to operate.

  • Thermal Energy Method (TEM)

             The thermal energy method (TEM) is also known as thermal deburring. In this process, an explosive gas mixture is used in a very controlled way that provides the thermal energy to burn off the burrs. This method is specifically used to remove those burrs that are tough to reach or having multiple surfaces at the same time. This is comparatively a faster method and needs only 20 ms to remove the burr. Also, this method works for multiple parts at the same time and the efficiency can be improved a lot.

  • Mechanical Deburring

In mechanical deburring, we apply grinding or rolling to remove the burrs to smoothen the parts’ surface. This method is faster and offers a high-quality finishing and cost-efficient.And the problem is that it’s only feasible for small products.

  • Tumbling Deburring

Tumbling Deburring is a deburring process that utilizes abrasive media and a rotatory barrel to remove irregular edges and flashes from the surface of the workpiece is known as tumbling (also known as rumbling). The parts that need deburring are put inside a horizontal barrel and then it is rotated. Since all the burred parts are being rotated and here, gravity comes into play and removes the unwanted material layers. The changes may also be adopted in media, water, or other lubricants. These depend on the type of burrs your material having. One more thing, the rotatory barrels can also have rubber vanes in them. When parts are rotated inside it, they will interact with the burred materials and this interaction will result in their removal. According to the geometry of the part, a broad range of media materials can be chosen from. Such as sand, granite chips, slag, steel, ceramics, synthetics, etc. This deburring method is cost-effective in terms of process and labor costs. Because a large number of parts can be deburred inside a single barrel by the worker.

Conclusion

First of all, if you want a shiny and smooth-surfaced product then your operators must have master skills in the field of CNC machining. These skilled operators can excessively reduce the burrs. Second, what type of burr will occur in your product, depends on the processing method and tools used. Then you can choose from any of the above-mentioned deburring methods accordingly that suit the most and offers the best results.

Keep one thing in mind, burrs can badly affect your mass production and it will disturb processing efficiency and quality inurn. Therefore, you must consider the factor of burring seriously to get high quality and smooth surface products.

Cora Feng
Cora Feng

Project Manager working on CNC Machining since 2010

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