If you work with metal, you’ll know that even after stamping and machining, many pieces require additional finishing before they can be assembled or shipped. One of the final processing steps is deburring, which removes any burrs and sharp edges that affect an affected part's safety and functionality.
This blog will go over what causes burrs to form, why removing them is so critical, and what deburring methods yield the best results.
What Causes Burring?
Burrs are small imperfections, such as metal protrusions or small ridges, that form when one or more machining processes (e.g., stamping, forming, or casting) don't work perfectly. Burrs can appear at several different stages in the machining process, including:
These various processes can create different types of burrs. There are three main types burrs:
Rollover burrs:These burrs, which resemble tiny pieces of curled metal, are the most commonly-seen type.
Breakout burrs:As their name suggests, these burrs have an upward shape, making them look like they are breaking out of the metal surface.
Poisson burrs:Poisson burrs form when excess amounts of metal collect at the end of the workpiece and extend sideways.
Regardless of type, burrs compromise the quality of the completed piece if not removed. They can decrease fracture resistance, increase localized stress and susceptibility to corrosion, interfere with finishing processes like electroplating or powder coating, and diminish overall product safety. Deburring removes these defects so that you’re left with a smooth and functional metal part.
How Do You Deburr Metal?
There are different ways to deburr metal. Depending on your application and the metal in question, you may opt for one of the following methods.
This is the most common and cost-effective approach. Using simple tools, you scrape the burrs away by hand. It’s easy to do but takes time, making it better suited to small shops where productivity isn’t an issue. Best results are seen for smaller burrs and simpler workpieces.
With this process, you use a deburring machine to grind the imperfections away. While more expensive than manual deburring, it’s also more efficient, which is why it’s the method of choice in most machining operations. By eliminating the need for hand sanding and grinding, it increases productivity and improves finished results.
You can use this method to deburr the inner parts of a hole. A spring-loaded cutting tool mounted on a spindle is positioned so that it can move through the hole smoothly and cut the burr without scratching or otherwise damaging the surface. Some cutting tools have a tapered end that creates a chamfer when it enters the hole.
With punch deburring, you use a punching machine. It requires different die types to achieve results, including rough blanking dies, fine blanking dies, and sizing dies. While this method is more efficient than manual deburring, you’ll need to use special tools, and complex structures will present challenges.
This method uses a salt or glycol solution to conduct electrochemical energy through the burrs, blasting them away while leaving the surrounding metal intact. This process is recommended when working with challenging metals, reaching tight areas, or ensuring exact results.
With thermal deburring, you generate thermal energy using combustive gases and scald the burrs out of the metal. It is recommended for eliminating hard-to-reach burrs in cracks or crevices or removing burrs on several surfaces simultaneously.
Electrolytic deburring involves the selective removal of surface imperfections from a workpiece using an electric current to convert the metal to its ions. Caution needs to be taken with this method because the electrolyte is corrosive and can affect the surface surrounding the burring.
If you work with softer metal parts, vibratory finishing is a gentler but still effective way to deburr them. The part is placed in a vibrating bowl or rotating barrel, along with a combination of abrasive and liquid components. As the machine rotates, this finishing media rubs continuously against the part to remove imperfections like burrs and sharp edges.
With this method, the parts are placed in a barrel, which rotates at high speed to tumble the pieces together and remove burring. Barrel tumbling can also be used to clean, descale, and remove rust from metal parts.
Using special equipment, you quickly drop the temperature so that the burrs become brittle before spraying pellets to remove them. You can use freezing if you work with smaller pieces that have a thinner burr wall.
Deburring machines may be designed for wet applications. Some machined materials produce combustible dust that can easily be ignited when you start grinding the metal. Wet machines moisten this dust as they work, preventing it from catching fire.
How Does a Deburring Machine Work?
Most deburring machines use belt, disc, or brush heads to grind burrs off of workpiece surfaces. While some machines have a single head, others have several, enabling it to carry out multiple functions and work on a wider range of pieces.
Abrasive belts run on rotating drums, allowing them to effectively remove burrs from the sides and edges of a metal workpiece.
Disc heads have rotating pads that are well-suited for processing delicate parts. These pads produce a unique pattern that protects the metal from fracturing under stress.
Rotating brush heads are recommended for more delicate parts because they remove burrs without damaging the surface coatings. The bristles can also round edges and reach difficult areas like cracks and crevices.
When choosing a deburring machine for your application, you’ll want to consider the parts that you work with. The level of deburring you need depends on the following characteristics of the finished product
Coatings used, such as cladding or paint
Designed quality of the finished part
For example, some parts are fine when you remove only the vertical burrs and leave the lateral ones untouched. However, if superior quality is a must, you will need a more versatile machine with advanced burring tools.
What Abrasives Do Deburring Machines Use?
Most deburring tools are coated with abrasives that wear down the burrs and smooth the machined metal surface. Grain size and materials will vary based on the hardness of the metal, but commonly-used abrasives include:
The industry standard for common applications, aluminum oxide comes in two versions: closed coat, which is ideal for metal grinding and weld removal, and open coat, which is more appropriate for processing wood. The grains are highly friable, meaning that they fragment during use to provide a consistently sharp cutting surface.
This specialty abrasive delivers a consistent and even cut, making it a recommended solution for finish work. Although more expensive than aluminum oxide, silicon carbide delivers a more consistent result and can even remove material without heat buildup, making it especially useful for heat-sensitive applications.
Ceramic is extremely hard and sharp, making it a premium abrasive grain. It also has the longest lifespan of any abrasive material. It cuts metal and other hard material aggressively without losing its sharpness.
Zirconia is an excellent choice for grinding and polishing of metal as well as stock removal in hardwoods. Before ceramic came on the market, zirconia was the most durable and heavy-duty abrasive grain.
Below are some tips you can leverage for faster and safer deburring at your shop.
Go for Automatic Deburring
As mentioned earlier, many metalworkers deburr their pieces by hand after cutting. Manual grinding, however, takes time, affects productivity, and can impact the consistency of your results. Deburring machines will finish your parts more quickly while ensuring a smooth and uniform finish on each one.
Use Cutting Fluid
Cutting fluids are used as lubricants during metalworking. They mitigate heat and resistance levels so that you don’t have to keep shutting down your deburring system to avoid friction damage and chattering. Cutting fluids also speed up deburring while reducing friction and wear, resulting in faster parts processing.
Use Rotary Brushes on Surface Coatings
If you produce metal parts with surface coatings, there’s always a risk that deburring will damage the coating. Rotary brushes will uniformly deburr and finish the edges in a single pass, saving time and money while leaving the coating intact.
About Red Label Abrasives
At Red Label Abrasives, we offer an extensive range ofsanding discs andsanding belts that will help you meet your facility’s deburring needs while ensuring consistently high product quality. If you have questions about your abrasives, our expert technicians can answer them and recommend the right product for your application. For more information, speak to a technician today by filling out ourcontact form or calling 844-824-1956.
David Kranker is a writer and creative maker who has been covering the abrasive and knife-making industries on the Red Label Abrasives Blog since 2020. David spends his time continually researching sanding and bladesmithing to provide readers with the latest and greatest information. In his free time, David utilizes abrasives for many different home and auto projects at his home in Delton, MI.