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Introduction to several advanced deburring processes (a)
- Jul 31, 2018 -

Burr is not common in machine knife, but very common in other industrial products.

 

Burr - People who have struggled in the metal industry must be familiar with it. In the processing of metal products, it is ubiquitous. No matter how advanced and sophisticated equipment you use, it will be born with the product. The so-called burr is mainly a kind of extra iron scrap generated by the plastic deformation of the material and processed at the edge of the processed material, especially the material with good ductility or toughness, which is particularly prone to burrs, and the burr problem is the metal processing industry. One of the challenges that engineers have not been able to solve so far.


The types of burrs in metal processing mainly include flash burrs, sharp burrs, splashes and the like, and a prominent excess metal residue that does not meet the design requirements of the product. For this problem, there is no effective method to eliminate it in the production process so far, so in order to ensure the design requirements of the products, engineers only have to work on the removal of the latter, so far different products are different. There are many methods and equipment for removing burrs.


In general, the methods of removing burrs can be divided into four categories:

Thick grade (hard contact): This category includes cutting, grinding, boring and scraping.

Ordinary grade (soft touch): This category is abrasive belt grinding, grinding, elastic grinding and polishing.

Precision grade (flexible contact): This category includes processing, electrochemical machining, electrolytic grinding and rolling.


Ultra-precision (precise contact): This type of deburring method, such as abrasive flow deburring, magnetic grinding deburring, electrolytic deburring, thermal deburring, and dense radium ultrasonic deburring, etc. Part processing accuracy.


When we choose the deburring method, we should consider various factors, such as the material properties of the part, the shape of the part, the size and precision of the part, especially the changes of surface roughness, dimensional tolerance, deformation and residual stress.

Electrolytic deburring is a chemical deburring method that removes burrs from machining, grinding, and stamping, and rounds or chamfers the edges of metal parts.


An electrolytic processing method for removing burrs of metal parts by electrolysis, referred to as ECD in English. Place the tool cathode (usually brass) in the vicinity of the burr of the workpiece, with a certain gap (usually 0.3 - 1 mm). The conductive portion of the tool cathode is aligned with the burr edge, and the other surfaces are covered with an insulating layer to concentrate the electrolysis on the burr portion. When processing, the tool is connected to the cathode of the DC power supply, and the workpiece is connected to the positive pole of the DC power supply. A low pressure electrolyte (typically sodium nitrate or sodium chlorate solution) with a pressure of 0.1 - 0.3 MPa flows between the workpiece and the cathode. When the DC power is turned on, the burr is dissolved and removed, and is carried away by the electrolyte.


The electrolyte is corrosive, and the workpiece should be cleaned and rust-proofed after deburring. Electrolytic deburring is suitable for removing burrs of cross-holes or complex-shaped parts in hidden parts of parts, and the production efficiency is high. The deburring time generally takes only a few seconds to several tens of seconds. This method is commonly used for deburring of gears, splines, connecting rods, valve bodies and crankshaft oil passage orifices, as well as rounding of sharp corners. The disadvantage is that the vicinity of the burr of the part is also subjected to electrolysis, and the surface will lose its original luster and even affect the dimensional accuracy.


Of course, in addition to electrolytic deburring, there are several special methods for deburring:


First, the abrasive flow deburring

Abrasive Flow Processing Technology (AFM) is a new deburring process developed in the late 1970s. This process is especially suitable for burrs that have just entered the finishing stage, but for small and long holes and metal molds that are not accessible at the bottom. It is not suitable for processing.


Second, magnetic grinding deburring

This method originated in the former Soviet Union, Bulgaria and other Eastern European countries in the 1960s. In the mid-1980s, the Japanese car made an in-depth study of its mechanism and application.

During the magnetic grinding, the workpiece is placed in the magnetic field formed by the two magnetic poles, and the magnetic abrasive is placed in the gap between the workpiece and the magnetic pole. The abrasive is aligned along the magnetic field line under the action of the magnetic field force to form a soft and rigid magnetic grinding. Brush, when the workpiece rotates in the magnetic field for axial vibration, the workpiece and the abrasive move relative to each other, the abrasive brush grinds the surface of the workpiece; the magnetic grinding method can grind and deburr the parts efficiently and quickly, suitable for Various materials, various sizes, and various structural parts are a kind of finishing method with low investment, high efficiency, wide application and good quality. At present, foreign countries have been able to grind and deburr the rotating inner and outer surfaces, flat parts, gear teeth, complex surfaces, etc., remove the oxide scale on the wire and wire, and clean the printed circuit board.


Third, thermal deburring 

Thermal deburring (TED) is the burning of burrs by the high temperature generated by the deflagration of a mixture of hydrogen-oxygen gas or oxygen and natural gas. Oxygen and oxygen or natural gas and oxygen are introduced into a closed container, and the spark plug ignites, so that the mixture detonates in a moment to release a large amount of heat energy to remove the burr. However, after the workpiece is burned and burned, its oxidized powder adheres to the surface of the workpiece and must be cleaned or pickled.


Fourth, dense radium strong ultrasonic deburring

The high-density ultrasonic deburring technology is a deburring method that has been popular in recent years. The cleaning efficiency is only 10-20 times that of the ordinary ultrasonic cleaning machine. The holes are evenly covered in the water tank, so that the ultrasonic waves do not need to be used. The cleaning agent can be completed simultaneously in 5-15 minutes.