2 Grinding Technology Experimental process for alumina ceramics with resin bond diamond wheel
Resin bond diamond wheel is used for grinding alumina ceramics. Study the specific transformation rules of grinding parameters by grinding experiments and adjusting the parameters.
In order to improve the basic grinding quality level of alumina ceramic material, resin bond diamond wheels with the roughness size range of 125-150μm and 38-45μm are used. Further analyze the roughness of the workpiece surface, material removal mode and the removal ratio in the grinding experiment, and obtain the data patterns of grinding parameters.
1. Types of alumina ceramics
The main ceramic material is alumina material during the grinding of alumina ceramics. With high conductivity, mechanical properties and stability of alumina ceramics, ultrasonic technology is required for basic processing.
1.1High purity
High purity alumina ceramics mainly refer to the ceramic materials with the total alumina content 99.9%. In addition, the basic sintered temperature of this material reaches up to 1990℃, it is usually able to made into fused glass and can be made into circuit boards.
1.2Ordinary alumina
Ordinary alumina ceramics mainly refer to the relatively low content of alumina material.
2 Grinding Technology Experimental process for alumina ceramics with resin bond diamond wheel
Diamond grinding wheels with the grain size to be controlled between 125-150μm and 38-45μm, outer diameter 400mm, inner diameter 127mm, width 25mm, thickness 10mm and concentration 100%, are used for grinding alumina ceramics.
The grinding technology adopts MM7312A precision horizontal grinding machine, and the machining mode is repeated mode. The spindle of grinding wheel should ensure a speed of 1500rpm/min, and minimum feed rate of grinding wheel is 1μm, and use water-based grinding fluid. The alumina ceramics is a block structure with a size of 50 × 50mm.
By comparing different grinding depths and feed rates, study the surface roughness and external structural changes of alumina ceramic workpieces, and finally choose the suitable machining parameters and machining technology.
The surface roughness of the workpieces need to be measured for completing the technical machining. Measure in detail the actual thickness with a micrometer before and after processing, and calculate the actual removal amount. Observe the actual morphology and appearance of the workpiece surface in detail with a three-dimensional microscope.
Roughness needs to be tested at least three times and the average value should be taken. When testing and measuring the workpiece thickness, the data should be taken three times and the average value should be obtained.
3.Grinding technology test results of alumina ceramic
3.1 Surface roughness
After comparison, due to there is the direct relationship between the surface roughness of workpiece and diamond grain size during the grinding, the smaller the diamond grain size is, the lower the surface roughness of the workpiece is.
In addition to the diamond grain size, the feed rate and the wheel speed also affect the surface roughness of the workpiece when machining.
3.2 Sample removal ratio
Use grain size 125-150μm. When the feed depth is 1-2μm, the sample removal ratio will increase with the moving speed of the workpiece , and then gradually decrease.
When the cutting depth is 3-4μm, the overall removal ratio of the workpiece can reach 80%. This indicates that the movement speed of the workpiece has relatively small impact on the material’s removal ratio.
In addition, there is a clear boundary limitation between the curve proportions of different cutting depths and removal degrees of the workpiece. The main reason is that as the material cutting depth continuous to increase, the deformation caused by the structural elasticity of the resin bond diamond grinding wheel has a relatively small impact on the overall removal ratio of the workpiece, while the impact of grinding wheel with coarse grain on the edge is relatively small.
Therefore, once the cutting depth continuous to decrease, the structural depth generated by the grain cutting is relatively shallow, it not able to fully utilize the ability to remove materials. Therefore, the cutting depth of the grinding wheel is 1-2μm, the overall removal ratio of the material is relatively low.
Once the cutting depth is 4μm, and the movement and feed speed of the workpiece can reach 0.25m/s, and the overall material removal structure proportion can reach 95%.
Conclusion:
With the high hardness and widespread brittleness, the alumina ceramics has become a typical hard and brittle material that is difficult to process. Therefore, it is important to adopt high quality diamond grinding wheels to improve the processing quality of special alumina.
Resin bond diamond wheel is used in this test, but vitrified bond diamond grinding wheels with excellent performance are widely used for grinding alumina ceramics.
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