Anyone familiar with machining and machining processes knows about burrs. No matter how advanced and sophisticated the equipment you use in the machining process, it will be accompanied by the product. They arise for several reasons. Some are due to plastic deformation caused by the cutting process, others are casting, forging and other flying edge processing processes, and some are welding extrusion waste. Burr negatively affects processing accuracy, assembly accuracy, post-processing positioning and appearance quality and many other aspects.
What is deburring?
A burr is a defect in the surface of a metal that may appear as an irregular edge on the metal end of a cold cut, hot saw or flame cut, and as excess metal in the weld during welding operations. The edges of cold-cut products often also have burrs, and the thickness of the burr depends on the gap between the knife blades.
Because burrs generally cannot be removed, products in general may have burrs up to a certain height. However, the internal and external burrs of the welded pipes must be shaved off. If not removed, they will affect the performance of the part. During the machining process, any type of deburring tool helps maintain the exact shape of the parts.
What is automated deburring?
Automated deburring is an innovative technology for rounding edges of machine parts. It is ideal for rounding hard metals, removing unwanted materials and ensuring a smooth production process.
Advantages of automated deburring
- Automated deburring applications improve the deburring and manufacturing process by increasing productivity and quickly removing burrs.
- Robotic deburring completes all tasks faster and improves quality compared to manual deburring.
- Any deburring tool or machine allows you to deburr all edges of machine parts that are difficult to reach with manual deburring.
- The implementation of deburring processes is simplified by automatic systems.
Why is deburring necessary?
Deburring is extremely important because burrs that are not removed can significantly affect the correct manufacture and assembly of parts.
Burrs increase the risk of injury to personnel
Whether during the transport and assembly of parts or during product use and maintenance: burrs such as sharp edges can cause injuries to employees and thus increase the risk of injuries at work.
Burrs accelerate equipment wear
Some bending and straightening machines create burrs during operation. If parts are processed without first removing burrs, these machines and some tools significantly accelerate wear and shorten the life of the machine, which inevitably leads to higher maintenance and repair costs in companies.
Burrs make additional precision machining difficult
To further prepare the machining and obtain a better surface finish, deburring is the most important step. Regardless of whether it is mechanical finishing or surface oxidation, if the burrs are not removed beforehand, a lot of residual material will accumulate on the narrow edge during the process, which may cause some defects during plating or welding.
In other words, timely deburring before surface treatment can prepare the next mechanical processing and ensure the quality of surface coating and reduce the breakage rate of mechanical tools.
Different types of cutters
Burrs can be divided into two main categories depending on their shape and formation mechanism.
Classification by shape
The main types and shapes of burrs in metal processing are flying-edged burrs, sharp-edged burrs, and splashes.
Flying edge
Also known as overflow, burr, etc., it generally occurs when the mold is opened and closed, for example, at the interface of dynamic and static molds, the sliding part of the slide, and the flying edges. These are largely caused by a failure in the clamping force of the mold or machine.
Sharp ridges
The sharp burrs take the form of shards of glass with sharp edges. Some of them are high strength, the bottom of the cutting surface is rough.
Squirt
Spatter generally occurs when molten metal passes into the weld pool. Pieces of molten metal wire accidentally fly out of the molten pool. If metal spatter flies out of the weld pool after solidification, it will not be cast cleanly onto the surface or edge of the part.
Classification by education mechanism
Burrs are classified according to the mechanism by which they form. The distinction is mainly made between Poisson, tipping, tearing, cutting and hot burrs.
Poisson pine . In this process, pressure is applied to the material in different directions, which leads to plastic deformation and stretching of the edges of the contact area and then creates the burr. Also during the cutting process, when the tip of the cutting tool grinds the workpiece, the cutting tool is deformed due to compression forces. These deformations result in the formation of an entry burr at the entry point of the cutting tool.
Drum Cutter . These are caused by bending of the tool path. When the cutting tool stops cutting, some residual material moves with the tool and bends toward the entry point or cutting edge. Depth of cut can also be a factor in burr formation, as the chips or rolls become thicker as the depth increases. To effectively prevent this burr, materials with sufficient ductility must be used so that the chips do not easily come out of the part.
Bags form under the eyes . These are burrs that occur when the part is plastically deformed and not cut. In simple terms, this can be understood to mean that the material has been torn away from the workpiece.
Cut burr . It is the residue that results from the separation or detachment of the cut part from the main part and may appear as a protruding ridge or irregular depression. Cutting burrs occur mainly on sawn parts and automatic screwdrivers.
Hot ridges . They are often called slags, spatters, or floats. They arise from the formation of hardened molten metal during welding, plasma and laser cutting due to residual stresses caused by uncontrolled heating and cooling.
4 different types of deburring
In general, deburring processes can be divided into four main categories.
Rough level (difficult contact)
The processing methods that belong to the coarse level are cutting, milling, gear cutting, sanding and smoothing. This is the deburring process or method commonly used by most companies, using files, sandpaper, grinding heads, etc.
Evaluation: Because the coarse level can only remove burrs from simple products with external structure, it is not effective for removing complex parts with cross-hole structure. The technical requirements for workers are not very high, efficiency is not high, and labor costs are high.
General grade (soft contact)
Common procedures include belt grinding, grinding, elastic wheel grinding and polishing. For example, this grinding deburring method mainly includes vibration, roller, sandblasting, etc. Companies like to use this method for initial deburring of parts.
Assessment: Can remove large surface burrs on a flat area. The removal area is large, but there is a problem of messy removal. Therefore, subsequent manual processing or other residual deburring methods must be carried out. Small products in large quantities are best suited for such methods.
Fine quality (flexible contact)
Fineness classifications include washing process, electrochemical machining, electropolished grinding and rolling process. Among them, high-precision die deburring is deburring through the cooperation of die machines and punching machines.
Assessment: The production of additional punching tools (thick tool + thin tool) and, if necessary, the production of molding tools is subject to a charge. It is more suitable for products with simple parting surfaces and is much more effective than manual operation in both operating efficiency and deburring effect.
Ultra-precision balance (precision contact)
Ultra-precision level processes include friction flow deburring, magnetic milling deburring and electric deburring. Electrolytic deburring is a chemical deburring process abbreviated as ECD. It can quickly remove burrs caused by machining, milling and punching, and provide metal parts with rounded or chamfered edges.
During operation, the tool's cathode is connected to the negative pole and the workpiece to the positive pole, allowing a low-pressure electrolyte to flow between the workpiece and the cathode. When direct current is turned on, the burr is dissolved by the electrical solution and removed from the part. It should be noted that the electrolytic solution is corrosive and the part must be washed and rustproofed immediately after the electrolytic deburring process.
Evaluation: Electrolytic deburring plays an important role in deburring hidden parts of cross holes or complex shaped parts. The efficiency of deburring work only takes a few tens of seconds, which greatly improves productivity. At the same time, the cost of precision contact is relatively high.
The most commonly used deburring methods
There are many deburring methods, including mechanical deburring, manual deburring, electrochemical deburring and thermal deburring.
Mechanical deburring
Mechanical deburring is characterized by the use of directly driven deburring tools. Through targeted internal and external deburring, burr-free components with rounded or chamfered edges are created. Brushes, cutters, polishing tools and galvanic instruments are used for deburring. Personalized products also play an important role. Mechanical deburring is extremely reliable for complex shapes.
Manual deburring
Manual deburring removes burrs, sharp and unfinished edges from the surface of a part. Manual deburring is an extremely versatile but time-consuming method. Furthermore, different types of tools can be used in manual deburring.
Electrochemical deburring
Electrochemical deburring is a deburring process that removes hard metals at high speed but in a safe manner.
Thermal energy method
This method combines fuel, oxygen and heat. Thermal deburring is an excellent method for removing burrs.
Summary
With increasing industrialization and automation, metal surface treatment methods are increasingly being used in automotive, aerospace, semiconductor, instrumentation and other application areas. Demands for precision in the production of mechanical parts and the miniaturization of institutional design are also increasing.
Therefore, deburring processes, methods and technologies for finishing parts tend to become more precise and ultra-precise, intelligent and automated, which invariably improves product quality and increases productivity and production efficiency.
