What Is Deburring?
To understand what the word deburring means, it is essential first to explain what a burr is. Burrs are rough edges or ridges left on a metal surface or any other object by machines. Now, for precision and accurate functioning of parts, these burrs must be removed. Deburring is the word used to refer to the process of removing the rough edges or ridges on part surfaces.
Advantages Of Deburring
Since burrs are sharp and rough, metals with burrs can cause harm when handled by workers or clients. Deburring, therefore, ensures the safety of personnel.
Working with parts that have burrs on their surfaces could cause damage to machines. To avoid such damages, ensure that all the metals are deburred.
Deburring your workpieces could be one of the contributing factors to the durability of parts. It is because wear and friction between surfaces are minimized.
Working with smooth parts is simple and fast, making each cycle of, for instance, assembling, quick. Therefore, deburring saves on time and ensures high throughput.
Manual deburring is very economical and is the most commonly used method among manufacturers. Technicians employ simple tools to buff or scrape the burrs from the metal parts by hand. Hand-held tools involved in manual deburring include brushes, sanders, grinders, demurrers, files, and many others.
Some manual deburring methods include brushing, bonded abrasive finishing, metal edging, and many others. Manual deburring is mostly employed in applications that do not require tight tolerances and consistency. Though the manual deburring process is easy, it takes a lot of time, affecting the overall production process.
Mechanical deburring employs the use of a deburring machine used for grinding off the burr. Unlike manual deburring, the operator does not do much of the work in mechanical deburring. The machine does. Machines involved in mechanical deburring include;
Barrel tumblers – parts and the abrasive media are loaded onto the chamber or barrel. The barrel also contains other unique compounds needed for specific surface finishes. Barrel tumbling methods can be either wet or dry tumbling, where wet barrel tumbling requires water and dry tumbling doesn’t. Mechanical deburring is more expensive than manual deburring; however, it is also very efficient.
Thermal deburring employs combustive gases like nitrogen that generate thermal energy to scorch the burrs from parts. Parts are exposed to high thermal energy for a short period. This is to ensure that other parts are not affected by the heat.
A thermal shockwave generated by the hot corrosive gas is responsible for vaporizing the burr away from the surface. Metals with low thermal conductivity can be deburred easily through this method. Thermal deburring is recommended for burrs that are not easy to reach, like cracks and crevices or multiple surfaces.
Electrochemical deburring employs a solution containing glycol or salt, which aids in conducting energy into the burrs. In other words, this method uses the knowledge of electrolysis where the charges concentrate in parts having less interelectrode gaps.
The cathodic tool acts as the negative pole, the metal part acts as the positive pole, and the electrolyte completes the circuit. The negative pole aids in focusing electrolysis on the areas of the metal part with burrs. Other parts of the tool are insulated to avoid unnecessary dissolving. Electrochemical deburring is suitable for high precision operations and challenging metals.
Robotic deburring employs a deburring, grinding, or chamfering tool set up on a robotic machine. Technological advances led to the development of methods that would do away with inconsistency, labor intensiveness, and slow turnover.
Robotic deburring is one way to eliminate the need for human labor leading to efficiency and consistency. A CNC feature is also implemented to enable the entry of parameters like movement, speed, and force of the machine. One of the limitations of robotic deburring is the high initial set-up cost. However, it has long-term benefits of low operating prices.
Vibratory deburring is almost similar to the working of barrel tumblers. This is because it also loads the abrasive media with parts and other unique compounds into a chamber. An outstanding difference is that the vibratory machine vibrates to create movement within the chamber.
The barrel tumblers create movement by rotation. The vibratory deburring machine has its chamber set up on springs, enabling it to move separately from its foundation. A weight away from the center is responsible for shaking the contents within the chamber. There are various machine configurations, including tubs, bowls, or troughs.
Waterjet deburring employs the same principle as the one used in waterjet cutting. The only difference is that waterjet deburring is set at lower pressures to avoid damaging parts. Therefore, waterjet deburring is unsuitable for removing larger burrs because of the low pressure.
Waterjet deburring method is recommended when there is a need to remove thin and lightly attached burrs. A high-velocity waterjet eliminates debris and burrs from metal parts resulting in oil-free parts. Using the waterjet deburring method enables you to remove burrs from sections of your parts that other methods cannot access.
Cryogenic deburring is the method that uses cryogenic temperatures to aid in removing burrs from parts. Liquified nitrogen is added to the chamber that contains the parts for deburring. Liquid nitrogen is added in a flash to cool the chamber, embrittling burrs on the parts leading to breakage.
Cryogenic deburring is mostly used for plastics with the ability to withstand impact; however, it can also be used in other materials. Some plastic materials include acetal, ABS, polyurethane, PET, liquid crystal polymer, PPS, and nylon. The cryogenic deburring method keeps the integrity and precision of parts.
Just as the name suggests, hole deburring is the process of using deburring machines to get rid of burrs in holes. A machine or method used in deburring flat metal surfaces cannot be used to deburr holes in metals.
That is why it is essential to have a specific machine for deburring holes, which should be efficient and cost-effective. A cutting tool is spring-loaded and set up on a spindle to achieve a successful hole deburring. Approximate the position of the cutting tool to easily go through the hole on a workpiece to cut out the burrs.
Step-by-step Metal Deburring Process
At the design stage, an engineer or metalworker must develop a design that operators follow. Clear instructions must be written down, making sure that each operator has a clear understanding of what the requirements are. Some of the instructions that can appear on the design may include;
- Deburring is unnecessary, meaning the edges are not supposed to be deburred.
- Sharp edges should be removed- to eliminate the danger of handling such edges.
- All visible burrs to be removed- an instruction to deburr every burr visible to the human eye.
- All visible burrs at [x] magnification should be removed- this means removal of all sharp edges and any burr visible at the specific magnification.
- Break edges- this means that the edges should be made blunt.
- Round the edges to a given radius- an instruction to create curved edges to the specified radius
Instructions on how to inspect the deburring process must be given clearly. Also, the instructions should specify which devices to use when measuring and recording. The commonly used inspection methods include;
- Visual – the use of eyesight which is usually less precise
- Tactile – involves the use of different tools such as toothpicks to locate burrs
- Magnification – for checking minute amounts or burrs
- Metallurgical mounts – are only employed when other methods are not productive.
- Height gauge – specifically for determining the height of a burr
Choosing Right Deburring Technique
At this stage, the metalworker must choose a suitable deburring method for the application. There are various factors to be considered before selecting a machine and technique, including;
- Wet or dry techniques are recommended for work areas dealing with one specific metal type.
Wet techniques are suitable for procedures involving different metal types because they clean and cool products.
- Abrasive – you should choose the abrasive that will work best with your machine choice.
- Machine head – at this point, you should look at the advantages and disadvantages of a belt, disc, and brush heads.
At this stage, the removal of burrs takes place through the technique chosen in the above steps. The procedure will be determined by the deburring technique used.
Types Of Burrs
Rollover burrs are tiny bits of metals curling on the surface of parts that have been machined. Usually, these burrs are bent from the path of the cutting tool. The formation of the rollover burrs depends on the depth being cut because the thicker the cut, the thicker the rollover burr.
Poisson burrs are formed due to deformation and elongation of the area in contact with the cutter. Compressive pressure caused by the cutting tool as it strikes the metal surface creates a reaction that elongates the part. Poisson burrs are formed perpendicular to the direction of the tool.
Thermal burrs, also known as spatters, occur due to the hardening of liquid metal used in laser or plasma cutting. Thermal burrs and base metal parts have varying mechanical properties because of heating and rapid cooling. Such burrs can be removed by grinding or, in some cases, through manual brushing.
Cut-off burrs occur when leftover material remains on the surface of the workpiece as the cut section falls off. Additionally, cut-off burrs usually happen with cuts done through saws or automatic screw machines. Preventing cut-off burrs requires proper support of the metal’s two sides to the cut’s end.
Common Deburring Media
Ceramic media has an inherent hardness and durability hence capable of deburring various plastics, metals, and other materials.
Steel media is suitable for light deburring. Steel media is expensive; however, it is spotless with a minimal attrition rate.
Synthetic media comprises abrasives like silicon carbide, emery, or alumina enclosed within a softer material.
Plastic media can be formulated in low density, suitable for general-purpose or high density for various metals.
Organic media is usually used for deburring, especially when drying is needed, because it absorbs oil and water.
Metal Deburring Tips
Automatic deburring is the way to go because of its numerous advantages over manual deburring methods. Some of the benefits offered by automatic deburring include efficiency, consistency, accuracy, and quality. Another reason metalworkers should go for automatic deburring is to avoid injuries that come with manual deburring.
When working with metals during deburring, a lot of heat is generated between the metals and machines. Metalworkers are forced to stop working to allow machines to cool down, slows the operation. Cutting fluid in the form of oil, gel, or paste is used for cooling and lubrication.
Working with machines that incorporate deburring and finishes is cheaper and saves time when working with metals. Such a machine is designed with a brush head and belt making your operations more efficient and profitable. Using different machines for deburring and finishing wastes time and resources.
A deburring method of choice should be able to preserve the quality of parts while offering precision. Most of the methods used for deburring metal surfaces can cause damage to the surface coatings. Rotary brushing is an exception because it does not interfere with the coating and offers efficiency.
Deburring Tools And Equipment
Brush heads are suitable for small and delicate parts, such as parts with surface coatings.
Disc heads can work with delicate parts with a pattern that preserves the part quality.
Belt heads are suitable for removing burrs from the edges and sides of given parts.
People Also Ask:
Removing burrs is necessary because of the reasons listed below;
- During assembling, parts may not fit due to the presence of burrs.
- Cracks leading to damage of the part can occur because of the burrs.
- Parts with burrs are susceptible to corrosion.
- Removal of burrs increases the quality of parts.
Deburring is essential for smoothening sheet metal edges for high-quality products needed for other downstream processes. Deburring sheet metals is also necessary for aesthetic finishes, rounded edges, minimized corrosion, and increased quality.
Deburring is simple, especially when using the manual method, which is time-consuming and inconsistent. Automatic deburring is easier because you will key in all parameters through a CNC interface. Generally, the method chosen for deburring will determine how easy or complicated the process is.
Metals burrs are caused by metal machining processes such as forming, stamping, casting, turning, grinding, etc.
Deburring can be used in various industries to remove rough edges, improve quality, and increase efficiency. Some industries that need the services of deburring machines include automotive, aerospace, consumer, and many others.