The types of burrs in the metal processing process mainly include edge burrs, sharp burrs, splashes, and other protruding excess metal residues that do not meet the product design requirements. For this problem, there is no effective way to eliminate it in the production process so far. Therefore, in order to ensure the design requirements of the product, engineers can only work hard on the removal of burrs in the later stage. So far, there are many methods and equipment for different products to remove burrs.
Generally speaking, the methods of removing burrs can be divided into four categories
Rough grade (hard contact) belongs to this category, including cutting, grinding, filing and scraping processing.
Ordinary grade (soft contact): belongs to this category, including belt grinding, grinding, elastic grinding wheel grinding and polishing.
Precision grade (flexible contact): belongs to this category, including flushing, electrochemical processing, electrolytic grinding and rolling processing.
Ultra-precision grade (precision contact): belongs to this category, including abrasive flow deburring, magnetic grinding deburring, electrolytic deburring, thermal deburring and dense radium strong ultrasonic deburring, etc. This type of deburring method can obtain sufficient part processing accuracy.
When we choose a deburring method, we need to consider many factors, such as the material properties of the parts, the structural shape, the size and precision, and pay special attention to changes in surface roughness, dimensional tolerance, deformation and residual stress.
The so-called electrolytic deburring is a chemical deburring method that can remove burrs after machining, grinding and stamping, and round or chamfer the sharp edges of metal parts.
An electrolytic processing method that uses electrolysis to remove burrs from metal parts, referred to as ECD in English. The tool cathode (usually brass) is fixedly placed near the burred part of the workpiece, with a certain gap (usually 0.3 to 1 mm) between the two. The conductive part of the tool cathode is aligned with the burr edge, and the other surfaces are covered with an insulating layer to concentrate the electrolytic action on the burr part. During processing, the tool cathode is connected to the negative pole of the DC power supply, and the workpiece is connected to the positive pole of the DC power supply. A low-pressure electrolyte (usually sodium nitrate or sodium chlorate aqueous solution) with a pressure of 0.1 to 0.3 MPa flows between the workpiece and the cathode. When the DC power supply is turned on, the burrs are removed by anodic dissolution and carried away by the electrolyte.
The electrolyte is corrosive to a certain extent, and the workpiece should be cleaned and rust-proofed after deburring. Electrolytic deburring is suitable for removing burrs from hidden cross holes in parts or parts with complex shapes. It has high production efficiency and the deburring time generally only takes a few seconds to tens of seconds. This method is often used for deburring gears, splines, connecting rods, valve bodies and crankshaft oil passage openings, as well as rounding of sharp corners. The disadvantage is that the vicinity of the burrs of the parts is also affected by electrolysis, the surface will lose its original gloss, and even affect the dimensional accuracy.
Of course, in addition to electrolytic deburring, there are several special deburring methods:
1. Abrasive flow deburring
Abrasive flow machining (AFM) is a new finishing deburring process developed abroad in the late 1970s. This process is particularly suitable for burrs that have just entered the finishing stage, but it is not suitable for processing small and long holes and metal molds with blocked bottoms.
2. Magnetic grinding and deburring
This method originated in the former Soviet Union, Bulgaria and other Eastern European countries in the 1960s. In the mid-1980s, Japanese companies conducted in-depth research on its mechanism and application.
During magnetic grinding, the workpiece is placed in the magnetic field formed by two magnetic poles, and magnetic abrasives are placed in the gap between the workpiece and the magnetic poles. Under the action of the magnetic field force, the abrasives are neatly arranged along the direction of the magnetic lines of force to form a soft and rigid magnetic grinding brush. When the workpiece rotates and vibrates axially in the magnetic field, the workpiece and the abrasive move relative to each other, and the abrasive brush grinds the surface of the workpiece; the magnetic grinding method can grind and deburr parts efficiently and quickly, and is suitable for parts of various materials, sizes and structures. It is a finishing method with low investment, high efficiency, wide application and good quality. At present, foreign countries can grind and deburr the inner and outer surfaces of rotating bodies, flat parts, gear teeth, complex surfaces, etc., remove the oxide scale on wires and wires, and clean printed circuit boards.
3. Thermal deburring
Thermal deburring (TED) is to burn off the burrs with the high temperature generated by the explosion of the mixture of hydrogen and oxygen gas or oxygen and natural gas. It is to pass oxygen and oxygen or natural gas and oxygen into a closed container, ignite it through a spark plug, and make the mixture explode instantly to release a large amount of heat energy to remove the burrs. However, after the workpiece is exploded, its oxidized powder will adhere to the surface of the workpiece, and it must be cleaned or pickled.
4. Miluo strong ultrasonic deburring
Milei strong ultrasonic deburring technology is a deburring method that has become popular in recent years. The cleaning efficiency of the auxiliary is 10 to 20 times that of ordinary ultrasonic cleaning machines. The holes are evenly distributed in the water tank, so that the ultrasonic wave can be completed simultaneously within 5 to 15 minutes without the help of cleaning agents.
