一、The role of chamfer

General chamfer function is to remove burrs, beautiful. However, for the chamfer specifically pointed out in the drawing, it is generally the requirement of the installation process, such as the installation guide of the bearing, and some arc chamfers (or arc transition) can also reduce the stress concentration and strengthen the strength of the shaft parts! In addition, assembly is easy and generally carried out before the end of processing. On agricultural machinery parts, especially round accessories and round holes, the end face is often processed into a chamfer of about 45°. These chamfer has many functions, must be carefully viewed in the maintenance operation, and make full use of, otherwise it will bring many difficulties to the maintenance of agricultural machinery, and even cause unexpected failures.

二、Purpose and function of deburring

Mechanical parts in the process of processing and manufacturing, even the finishing process is inevitable there will be burrs. The existence of burrs will have adverse effects on machining accuracy, assembly accuracy, reprocessing positioning and appearance quality of parts. Burrs on parts that move relative to each other during assembly may cause surface wear or fall off inside the chassis, and the parts with coating on the exterior of the residual may rust or paint off due to scratches on the burrs. With the precision and miniaturization of the market demand in the field of precision instrumentation, the harm of burrs is becoming more and more obvious.

1、The influence of burrs on the function of parts and the performance of the whole machine

（1）The greater the burr on the surface of the part, the greater the energy consumed to overcome the resistance. Due to the presence of burrs, parts may not reach the fit position, if the fit position is reached, the rougher the unit area pressure is greater, and the surface is more prone to wear.

（2）The impact on the corrosion resistance of the parts and the whole machine after the surface treatment of the parts are touched off during the assembly, which will scratch the surface of other parts, and the surface of the burr will form a bare surface without surface protection. Under humid climate conditions, these surfaces are most prone to rust and mildew, which affects the corrosion resistance of the whole machine and leaves a quality hazard for the product.

2、The impact of burrs on subsequent work steps and other processes

（1）If the burr is too large on the crude base level, it will lead to uneven processing allowance during finishing. For example, when the thick aluminum plate is drilled in the row hole, the four sides of the sheet material allowance is not uniform, because the burr is too large, when the burr part is cut, the material removal amount will suddenly increase or decrease affecting the smoothness of the cutting, resulting in waste products.

（2）If there are burrs in the precision datum surface, the datum is not easy to coincide with the positioning datum, resulting in unqualified processing size.

（3）In the surface treatment process, such as the coating process, the coated metal will first gather at the tip of the burr site, resulting in nonconforming products.

（4）Burr is the main factor that is most likely to cause bonding in the heat treatment process burr is often the main reason for the destruction of interlayer insulation, which will lead to a significant decrease in the AC magnetism of the alloy, so some special materials such as soft magnet nickel alloy must be removed before heat treatment.

3、Burr control and prevention

（1）When arranging the processing order, the process that produces burrs should be arranged in the front as far as possible, and the process that does not produce burrs or has smaller burrs and a smaller number of burrs should be arranged in the back. For example, when there is a radial hole on the sleeve, when the center hole is turned first and the radial hole is drilled after, the end of the hole will produce burrs. Instead, the radial hole and the center hole are drilled first, and the burrs can be reduced or eliminated.

（2）Reasonable processing methods Reasonable processing methods should be selected in the process design to minimize the cost of deburring in the subsequent process. Under the premise of not affecting the production efficiency and processing cost, the processing method with fewer burrs is selected as far as possible. For example, when the cutting layer is thick and the cutting layer is thin, the cutting is smooth, and the burr is small. When the cutting layer is thin and the cutting layer is thick, the burr is large. Therefore, to reduce the milling burr should be as far as possible to use down milling. For example, when milling the plane with the end milling cutter milling, at the same time to participate in the cutting of the cutter teeth more and perpendicular to the machining plane cutting force is very large, so in the parts of the processing plane cutting side of the burr more, and the use of cylindrical milling cutter downmilling of the burr will be significantly reduced.

（3）According to the angular effect generated by burrs, the Angle between the machineed surface and its adjacent surface has a great relationship with the formation of burrs. The larger the edge of the part, the greater the root rigidity of the end of the cutting layer, the easier the cutting layer material is to be completely cut away, and the number and size of burrs will be smaller. Therefore, a reasonable cutting direction should be selected so that the final cutting edge is located in the part with a larger Angle. For example, the outer cone of the end of the turning sleeve part, when the turning tool from the outer circle to the cone end of the inner wall of the cone end is easy to produce burrs, if the direction of the cutting tool is changed, the turning tool from the inner hole of the cone end to the outer circle, because the Angle formed by the cone and the inner hole is smaller than the Angle formed by the cone and the outer circle, the outer circle is not easy to produce burrs.

（4）This method is suitable for the parts with the same shape size and the processing surface can be closely combined, and the two ends of the parts are superimposed neatly, so that the machining edge of one part is close to the machining edge of the other part, which effectively prevents and reduces the generation of burrs on the processing surface.

（5）For some precision parts that require strict control of burrs, advanced processing processes with fewer burrs can be used. For example, electroforming processing is the process of electrodeposition of metal on the casting mold or reproduction of metal products, the use of electroforming process can be precision optical instruments on the reflector, microwave instruments on the waveguide and other precision parts processing, because there is no mechanical cutting force in the processing process, so there will be no deformation and flash burr.

三、The role of the retracting slot

In order to facilitate the withdrawal of the tool during processing, and to ensure that the adjacent parts are tight during assembly, the tool withdrawal slot should be machined at the shoulder. The retracting groove and overpass groove are annular grooves made at the root of the shaft and the bottom of the hole. The function of the groove is to ensure that the processing is in place, and the second is to ensure that the end faces of adjacent parts are tight during assembly. Generally used in turning processing (such as the outer circle, boring, etc.) is called the cutting groove, and the grinding wheel overpass groove is called for grinding processing