Why your diamond cutting tools can not reach ideal precision?

 Diamond cutting tools widely used in ultra-precision machining

Single crystal diamond tools have high processing precision and long service life, and are widely used in ultra-precision cutting. In recent years, products processed with diamond tools (such as contact lenses, Fresnel lenses, photosensitive drums of copiers, etc.) have increasingly entered ordinary homes and workplaces. The wide application of diamond tools puts forward higher requirements for tool sharpening technology.

How to choose the grinding surface of diamond tool ？

Single crystal diamond crystals have the characteristics of high hardness and anisotropy, and there are large differences in physical and mechanical properties between different crystal planes. Diamond tools with different properties can be obtained by choosing different crystal planes as the grinding surface of the tool.

The sharpening surface of the tool should be determined according to the use requirements of the tool. Selecting (100) crystal plane as the front and flank face of the tool can obtain a diamond tool with higher strength; choosing (110) crystal face as the front and flank face of the tool A tool with high mechanical wear resistance can be obtained; the (110) crystal plane is used as the rake face of the tool, the (100) crystal plane is used as the flank face, or the (100) crystal plane is used for both the front and flank faces to obtain anti-wear Tools with high chemical wear resistance.

How to choose the appropriate diamond tool sharpening parameters

In precision and ultra-precision cutting, the most widely used is the arc edge diamond tool. The main goal of the manufacture of arc-edge diamond tools is to obtain a diamond tip with a sharp edge, a smooth blade surface, and a high-precision edge profile.Reasonable selection of sharpening parameters is of great significance for controlling the arc profile of the tool tip, the sharpness of the cutting edge and the surface roughness of the tool.

1.Abrasive size

Abrasive particle size refers to the particle size of diamond micropowder (the main component of sharpening paste) or the particle size of diamond grinding wheel. The effect of abrasive particle size on tool sharpening quality conforms to the grinding theory, that is, the finer the abrasive particle size, the smaller the grinding force, the less grinding heat generated, the less prone to chipping, and the lower the grinding rate. Get a sharper cutting edge.

The influence of different factors (disc speed, turning tool swing speed, turning tool feed, abrasive particle size, etc.) The results show that the particle size of diamond abrasive has the greatest influence on the arc profile of the tool tip.

2.Sharpening speed

The sharpening linear velocity has an important influence on the sharpening efficiency and sharpening quality of diamond tools. A larger sharpening linear velocity can bring higher sharpening efficiency, but it also increases the impact degree of diamond abrasive grains on the cutting edge. At the same time, due to the increase of the spindle speed, the rotation accuracy of the spindle is reduced, which will inevitably increase the end surface runout of the grinding disc, thereby reducing the contact accuracy between the diamond tool and the grinding disc, and increasing the radius of the blunt circle of the cutting edge. The experimental research on sharpening shows that with the continuous increase of the sharpening line speed, the radius of the blunt circle of the cutting edge also increases; by reasonably controlling the line speed and sharpening pressure during the tool sharpening process, the quality of the cutting edge Higher diamond cutters.

3.Sharpening pressure

The greater the sharpening pressure, the greater the interaction force between the diamond particles and the diamond tool, and the higher the sharpening efficiency. Too much pressure will cause chipping, and reducing the surface quality of the diamond tool will aggravate the wear of the grinding disc; too low pressure will cause insufficient contact between the tool and the grinding disc surface, affecting the contact accuracy between the tool and the grinding disc surface, resulting in a decrease in grinding quality . With the gradual increase of the sharpening pressure, the radius of the blunt circle of the cutting edge decreases first and then increases, and the optimum value of the pressure is 10N; when the sharpening pressure exceeds 15N, the surface quality of the tool decreases significantly. The effects of sharpening line speed, sharpening pressure, grinding disc and grinding powder on sharpening quality and sharpening efficiency have been studied through experiments. It is believed that increasing the sharpening positive pressure P will improve the sharpening efficiency. The increase of pressure and the increase of sharpening temperature can improve the sharpening efficiency of diamond.

4.Sharpening machine vibration

There are many factors that affect the sharpening quality and efficiency of single crystal diamond tools, such as the vibration of the sharpening machine, the surface quality of the grinding disc, the dynamic balance accuracy of the spindle, and the sharpening trajectory. Among them, the vibration of the sharpening machine is one of the main factors affecting the quality of diamond tool sharpening.

During the mechanical grinding process of diamond tools, the vibration interference of the grinding machine itself and its tool clamping system will reduce the contact accuracy between the diamond tool and the grinding disc, affecting the grinding accuracy and surface quality of the diamond tool. Especially in precision sharpening, vibration interference will directly affect the sharpness of the tool and the surface roughness of the tool. By testing the sharpening quality of the diamond tool before and after vibration isolation of the grinding machine tool, it is found that reducing the natural frequency and vibration amplitude of the machine tool and improving the contact accuracy between the diamond tool and the grinding disc can significantly improve the quality of the diamond tool. The vibration interference of the sharpening machine and the tool holder structure will also affect the sharpness and surface roughness of the tool, and the quality of tool sharpening can be significantly improved by improving the tool holder structure

Reasonable selection of the grinding surface, grinding direction, grinding parameters and reducing the vibration of the grinding machine can effectively improve the mechanical grinding quality and grinding efficiency of single crystal diamond tools.