During the CNC machining process of molds, burrs, as a common workpiece defect, often appear after cutting operations.
Especially in the drilling or milling process, these uninvited guests often form quietly at the bottom edge of the part, especially for those materials with good plasticity and low hardness, burrs appear more frequently.
Cause of burrs:
Exploring the cause of burrs, it is not difficult to find that when the material is cut to the last layer, it is very easy to deform and get out of the control of the cutting tool. When the part remains in a fixed position, these deformed materials are difficult to be completely removed, and remain on the edge in the form of a film, forming sharp burrs. These burrs not only affect the aesthetics of the workpiece, but are also likely to interfere with subsequent processing or use, so they must be removed.
The details are as follows:
①CNC milling parameters, milling temperature, cutting environment, etc. will also have a certain impact on the formation of burrs. The influence of some major factors such as feed speed and milling depth is reflected through the plane cutting angle theory and the tool tip exit sequence EOS theory, which will not be repeated here;
②The better the plasticity of the workpiece material, the easier it is to form type I burrs. In the process of end milling of brittle materials, if the feed amount or plane cutting angle is large, it is conducive to the formation of type III burrs (deficient);
③When the angle between the terminal surface of the workpiece and the machined plane is greater than a right angle, the formation of burrs can be suppressed due to the enhanced support stiffness of the terminal surface;
④The use of milling fluid is conducive to extending the tool life, reducing tool wear, lubricating the milling process, and thus reducing the burr size;
⑤Tool wear has a great influence on the formation of burrs. When the tool wears to a certain extent, the tool tip arc increases, not only the burr size in the tool exit direction increases, but also the tool cut-in direction will have type burrs. Its mechanism needs further in-depth research.
⑥ Other factors such as tool materials also have a certain influence on the formation of burrs. Under the same cutting conditions, diamond tools are more conducive to suppressing burr formation than other tools.
Methods for controlling milling burrs:
The formation of end milling burrs is affected by many factors. It is not only related to the specific milling process, but also to the workpiece structure, tool geometry and other factors. To reduce end milling burrs, it is necessary to control and reduce the generation of burrs from many aspects. There are many solutions to choose from. For example, reduce the feed speed and increase the tool rake angle, as follows:
Chemical deburring: Using chemical energy for processing, chemical ions will adhere to the surface of the part to form a film layer with high resistance and low conductivity to protect the workpiece from corrosion, and the burrs can be removed by chemical action because they are higher than the surface. This method is widely used in pneumatic, hydraulic, engineering machinery and other fields.
High temperature deburring: Put the part into a sealed chamber, pass a certain pressure of hydrogen and oxygen mixed gas and ignite it. The heat generated by the explosion can burn off the burrs without damaging the part itself.
Tumble deburring: The parts are placed in a closed drum together with the abrasive, and the burrs are removed by the rotation of the drum and the grinding action of the abrasive. Optional abrasives include quartz sand, wood chips, aluminum oxide, ceramics, and metal rings.
Manual deburring: Grinding is performed manually using tools such as steel files, sandpaper, and grinding heads. Although the efficiency is low, it is still an effective means when dealing with small-scale or simple workpieces.
Process deburring: Including edge rounding and chamfering, the process of removing the edges of metal parts through a series of process means. This method is usually associated with the operation of creating a specific radius of the edge of the part.
Electrolytic deburring: The burrs of metal parts are removed by electrolysis. The burrs are dissolved and carried away by the action of the electrolyte. It is suitable for removing burrs from hidden parts or parts with complex shapes in parts, and has high production efficiency.
High-pressure water jet deburring: The impact force of high-pressure water flow is used to remove burrs, which is suitable for the heart of the car and the hydraulic control system of engineering machinery.
Freeze deburring: After cooling to soften the burrs, the burrs are removed by ejecting projectiles. It is suitable for coarse burrs and small burrs of smaller products.
Punch deburring: Use a mold with a punch to remove burrs. It is suitable for simple sub-surface products.
Vibration deburring: Remove burrs by vibration and grinding. It is suitable for deburring large quantities of small products.
These methods have their own advantages and disadvantages. Of course, as a professional CNC processing service provider, we will choose the appropriate processing sequence method and structural design improvement method to suppress or reduce milling burrs. Customers don’t have to worry about this, because all processing problems will be considered and handled properly by CNC processing service providers. What is finally delivered to you is a perfect product. If you have CNC mass processing needs, you can choose Mulan Metal, which is a professional CNC precision machining, machining, and metal forming service provider with 12 years of metal forming manufacturing experience and complete certification certificates. It can quickly help you solve processing problems.
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