Meta fabrications involve various processes to create parts that suit your design requirement. Often, precision is a criterion of this manufacturing process; machinists want their parts and components to be without any imperfection.

However, achieving this is challenging, as even the most precise methods still risk developing one defect or another, with burrs being a common one. Therefore, machinists often need to engage in deburring, among other surface finishing processes, to build precision and desired quality into the fabrication. 

This article discusses deburring in-depth, exploring causes of burrs, reasons you need to deburr your parts, and other intricate details you need to understand. Let’s get right at it. 

What is Deburring?

Burrs are tiny defects, imperfections, or protrusions on the surface of machined metal parts, preventing a smooth surface finish. Manufacturers use a series of cutting processes during machining to create the desired components. However, some imperfections or undesirable ridges may occur, resulting in burrs.

The burrs may appear sharp, rough, or uneven, altering the aesthetics of the part and sometimes the functionality and safety of the machined product. Therefore, it is necessary to rid the machined part of this impurity, hence, deburring. So, what exactly is deburring?

deburring
deburring

Deburring simply means the removal of these imperfections – burrs. It involves a series of operations targeted at ridding the metal surface or machined part of burrs, sharp edges, rough spots, and other imperfections. Therefore, the result of deburring results in improving the part’s appearance, accuracy, safety, consistency, and overall quality.

Reasons for Deburring in Metal Fabrication

Deburring is an essential aspect of metal fabrication, as it helps improve the part’s safety, quality and functionality. Below is a more detailed review of the benefits of this post-processing operation.

Enhance Aesthetics and Surface Finish

Deburring improves the overall appearance of the part, creating a polished and professional finish. It helps to smoothen out imperfections and machining defects, ensuring better product quality and aesthetic appeal. Deburring is crucial for custom parts fabrication, as it helps enhance the aesthetic appeal of a part.

Safety Reasons 

Burrs, particularly the sharp ones, pose safety risks to the manufacturers, employees, and the end users. During transport, part assembly, installation and use of the product, the presence of burrs in the part increases the risk of injuries.

Reduce Wear and Tear of Cutting Tools 

Sometimes it’s almost inevitable to machine parts without creating burrs. However, these burrs during subsequent machining can increase the risk of tool wear and tear. Burrs increase the interaction with the tools and the workpiece, accelerating wear.

Enhance Precision and Part Functionality 

Deburring helps create a better surface finish, enhancing the part’s dimensional accuracy and precision. If you do not remove burrs from your fabrication, it may cause the accumulation of residual materials on the edge, causing more manufacturing defects. Also, deburring aids in easily fitting and assembling different components and promoting the parts’ functionality. 

Causes of Burrs During CNC Machining?

Indeed, CNC machining is a precise process; however, there’s still the potential for defects such as burrs. It may result from any processes, including drilling, milling, turning, and other cutting techniques like laser cutting, blanking and shearing.

Below are the likely causes of having burrs in your machined parts. 

Tool Wear 

Continuous use of machining tools, especially with poor maintenance practices, increases wear, reducing the tool’s efficiency. Therefore, the cutting edge becomes less effective and increases the chances of burr formation.

Material Properties 

The type of material you are machining, especially the thickness and quality, may also influence the risk of burr formation. High-quality materials always possess food machining properties, with less requirement for finishing and post-processing. However, poor-quality materials may increase the risk of burrs.

Operator’s Skill Level

Poor operator Skill level may also increase the chances of burr formation. To increase machining efficiency, a skilled operator understands the necessary parameters, such as the tool path strategy. Therefore, besides material properties and the machining process, the technician also plays a role in the machining defects. 

Feed Rates and Cutting Speed

This feature also relates to the operator’s skill level. Poor optimization of the cutting speed and feed rates may increase the risks of burr formation. Cutting at higher speeds increase heat build-up, increasing the chances of burr formation.

Inadequate Cooling and Lubrication

Insufficient cooling and lubrication during machining can cause heat build-up and overheating, increasing the risk of burrs and other imperfections. 

Classifications of Burrs

Depending on the shape and formation mechanism, burrs exhibit specific characteristics that make it possible to classify them. Below, we discussed the types of burrs. 

Based in Shape

Burrs are generally grouped into three categories, depending on their shape.

  • Sharp Burrs: As the name suggests, these burrs are in the shape of a broken glass with pointed and sharp edges. These are the kind of burrs likely to cause injuries if not removed. They are formed during cutting or shearing; consequently, they appear on the lower side of the cutting surface of the part. 
  • Flying Edge Burrs: They are also called phi or spill burrs. Flying edge burrs usually appear as long and thin projections extending beyond the material’s edge. Like other burrs, it may diminish the functionality and precision of the part. 
  • Splash Burrs: These burrs are common in die casting, occurring during the transition of the molten metal into solid. It may also occur during welding, having irregular shapes.

Based on the Formation Mechanism

This classification of burrs is the more popular approach, as it describes how they are formed during manufacturing of the components. Below, we explore three kinds of burrs based on this classification.  

  • Tumbling Burrs: These burrs firm from the tool path bending, causing the slight rotation or tumbling of metal particles during machining. As you machine the workpiece, some material may remain and move with the cutter, and gold points toward the cutting teeth.
  • Poisson Burrs: The name of this burrs traces to the term – poison effect – which refers to the expansions perpendicular to areas experiencing stress. Application of force on material, such as during cutting, causes deformation of the edges and creates burrs. This deformation presents itself as burrs on the entrance formed at the entry of the cutting edge. 
  • Tear Burrs: These burrs are formed by tearing when a material is plastically deformed and not completely shearing. It is common to CNC punching, where the sharp cutting edge is left along the contour of the punched hole. 
  • Hot Burrs: It is sometimes called thermal burrs, common to cutting or grinding. They are sometimes called slag or splash. It is formed when there is excessive heat build-up during cutting. It may also result from welding, plasma arc and laser cutting processes when uncontrolled cooling occurs. 
  • Cut-off Burrs: These burrs occur at the edges of cut-off parts, especially after processes such as milling or sawing. Cut-off burrs refer to the residual piece when cutting off components of a workpiece. They occur as a protrusion or unsmooth depression. It is common on saw cuts and auto screw machine parts. 

Types of Deburring

We can grade deburring into four main categories depending on the machining requirements. 

Coarse Grade

Deburring processing methods such as filing, milling, gearing, cutting and troweling belong to the coarse grade. This deburring method is achievable using simple tools like sandpaper, files, and abrasives. This kind of deburring is cost-effective, as it is simple and does not require intensive work. Moreover, it is ineffective for complex structures, especially those with holes. It’s suitable for simple products with little to no precision specification. 

General Grade

While this form of deburring isn’t sophisticated, it’s a notch higher than the coarse grade. It involves mechanical processes involving sandblasting, vibration, and rollers. The deburring processes include grinding, wheel grinding, belt grinding, and polishing. 

Also, it is less effective than the finer grade and often for parts with less precision requirements. However, it can serve as an initial deburring before further surface finishing. It is suitable for removing surface burrs, especially large ones, to improve the general appearance of the part. 

Fine Grade

Deburring processes belonging to the fine grades are basically finishing and flushing processes. They include techniques like electrochemical machining, rolling manufacturing and electropolished grinding. 

This form of deburring is suitable for parts with high-quality finishes, such as high-precision die deburring. Compared to the previous two, it is a more effective deburring method suitable for precision-standard industries. 

Ultra-precision Grade

Processes belonging to this level of deburring include magnetism milling deburring, electrical deburring, electrolytic chemical deburring, and friction flow deburring. The technique is targeted towards achieving a flawless surface finish, regardless of where the burrs may be hidden or the complexity of the machined part. 

It is highly efficient and suitable for parts with tight tolerance requirements. For example, the electrochemical process just requires connecting the workpiece to a chemical electric power source which then rids the components of the burrs.

Standard Methods of Deburring Imperfections

There are different methods of deburring and ridding your machined parts of imperfections. Below is an overview of the typical ones used by OEMs and engineers. 

Manual Deburring

As the name suggests, you do not use any machine or device to carry out this deburring process. Therefore, it is only simple to deburr a small component, where the machinist may use sharp tools like files, knives, grinders, sandpaper, or other suitable polishing tools. It is the traditional method of polishing machined parts, where you carefully examine the part and use the sharp end of your tool to remove the burrs. It is practical and versatile but stressful and time-consuming. However, the technique is almost impossible when working on a large object or volume. 

Electrochemical Deburring

This process of deburring is for when you have to remove burrs in areas that will be challenging for other methods. It’s typically for deburring small parts with areas challenging to reach. As the name indicates, the process uses an electrochemical process to rid such parts of the burrs. 

This deburring method uses an electrolytic solution – such as sodium chloride or sodium nitrite solution and electric current, with the workpiece attached to the circuit acting as an anode. The solution and the current will quickly remove the burrs. 

However, you should wrap portions of the part with insulating material to prevent dissolution of the workpiece. The process is fast, efficient and suitable for intricate components. Moreover, there’s no tool wear using this technique.

Hole Deburring

Like the previous methods, the name of this deburring technique explains what it’s about. It is the go-to method for removing burrs in a hole. It uses a spring-load cutting tool attached to a spindle. The machinist carefully positions the tool such that it penetrates the hole, removing the burrs. The process is fast, efficient and cost-effective for removing burrs in holes with little to no scratches or damage to the part.

Brushing

Brushing is a mechanical method of deburring. It involves scrubbing the surface of the machined part with an abrasive material – a brush. The principle of action is similar to using sandpaper and other manual tools for deburring. However, unlike manual methods, you may use a machine to hasten and amplify the process, increasing efficiency. 

Besides brushing, other mechanical deburring methods include grinding and rolling, polishing tools, milling cutters, and electrocuted instruments. This process is particularly beneficial for complex parts and structures.

Manufacturing Tips to Prevent Burss in Your Metal Fabrications

While burrs are a machining defect, it is a pretty common occurrence. Effective prevention of burrs during metal fabrication requires a combo of strategic practices. Below we give a brief overview of manufacturing tips to help you minimize or eliminate burrs in your fabrications.

Use a Cutting Fluid

Applying appropriate cutting fluids and lubricating agents during machining and metal cutting can help you reduce the risks of burr formation. Lubricants help to reduce the frictional force between the cutting teeth of the cutters and the workpiece. 

Moreover, after machining for extended periods, there’s heat build-up – one of the cases of burr formation. In this case, the lubricant can act as a coolant, reducing the rising temperature, preventing tool wear, friction and burr formation. Therefore, when machining parts, it is essential to use suitable cutting fluids and lubricating agents.

Use Rotary Brushes for Surface Finishing 

While many surface finishes help to rid your metal fabrications of burrs, they also alter or even damage the coatings of the product. Therefore, using rotary brushes is a better choice for surface finishing. The brushes effectively improve your parts’ surface properties and deburring simultaneously. Moreover, they are cost-effective, reducing the need for more sophisticated surface finishing as the components retain their coating. 

Try Automated Deburring

While manual and mechanical deburring are practical and cost-effective for ridding burrs in your metal fabrications. However, since it heavily depends on human interference, it is challenging to guarantee accuracy and consistency. Moreover, it slows the manufacturing times, increases the chances of other defects, or even diminishes your parts’ overall surface and quality. Using automated deburring machines helps to ensure a smooth, consistent finish with high precision, ridding all burrs in your metal fabrications.

Deburring and Finish 

Try to integrate deburring into your general surface finishing process. Some manufacturers choose to separate surface finishing procedures; this increases lead times and stresses the material. However, deburring and finishing simultaneously help you achieve that desired surface finish, quality standards and polished appearance.

Zintilon’s Expert Metal Fabrication Services 

While avoiding burrs and other imperfections is challenging during machining, partnering with an expert metal fabrication service is an intelligent move to achieving this. At Zintilon, we offer industry-standard part fabrication services, ranging from machining, die casting, rapid prototyping and other related technologies.

Our facilities consist of expert machinists and engineers with a proper understanding of ensuring your fabrication maintains all your desired specifications. Whether you need your part to be devoid of burrs or require more sophisticated finishing options, we are your best bet. 

Contact us today! 

Conclusion

We have established in this article that deburring is beyond just enhancing your parts’ aesthetics and surface properties. It’s also crucial in maintaining the precision and functionality of the components. However, there are different methods and grades, depending on your design specification. Just ensure to use the one that best suits your requirements to ensure a successful project.

FAQs

How Do Burrs Affect Metal Parts Fabrication?

Burrs generally affect the general properties of your metal parts, including the precision and functionality. It increases the risk of the part’s wear and tear, making part assembly challenging and posing safety concerns.

What is Deburring For?

Deburring is a post-processing step during metal parts fabrication. It helps to rid the manufactured parts of any imperfections, burrs and enhance the general surface features of the machined part.

How Do You Choose the Right Deburring Method for Your Metal Parts?

The deburring method for your fabrication depends on the material type and part geometry. However, an important feature is the desired finish of your design specifications requests. For example, fine and ultra-precision deburring methods are for parts requiring extreme tolerance specifications, such as aerospace industry components.

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