How to choose the grinding wheel for thermal spray coating grinding

       Grinding wheel hardness "refers to the ease with which abrasive particles fall off the surface of the grinding wheel under the action of grinding force. Generally, "grinding wheel hardness" is divided into 14 grades, namely: super soft (code CR), soft 1 (R1), Soft 2 (R2), Soft 3 (R3), Medium Soft 1 (ZR1), Medium Soft 2 (ZR2), Medium 1 (Z1), Medium 2 (Z2), Medium Hard 1 (ZY1), Medium Hard 2 (ZY2), Medium hard 3 (ZY3), hard 1 (Y1), hard 2 (Y2), super hard (CY), etc.



      "Wheel hardness" affects the "self-sharpening" of the grinding wheel, which is important for grinding thermal spray coatings. The general selection principle of "grinding wheel hardness" is that the higher the hardness of the material being processed, the softer the level of "grinding wheel hardness". This principle also applies to the grinding of thermally sprayed coatings.

    The hardness selection range of green silicon carbide grinding wheel is ZR~R (medium soft~soft). Soft 1 (R1) and Soft 3 (R3) have higher grinding efficiency.

    The hardness levels of synthetic diamond grinding wheels are ZR, Z, ZY, Y, and only synthetic diamond grinding wheels with resin adhesives have hardness levels. Generally, ZR grade and Z grade are used.

     Concentration is a performance index of diamond and cubic boron nitride grinding wheels, which refers to the content of diamond or cubic boron nitride per unit volume in the working layer of the grinding wheel. A grinding wheel containing (0.88g) (4.4 carats) of diamond or cubic boron nitride in a volume of 1cm3 is specified, and its concentration is said to be 100%. There are 5 kinds of concentrations, see Table 7-6,

    Choice of concentration. When rough grinding, the grinding wheel with high concentration should be selected, because there are more abrasive particles per unit area, and the cutting ability is strong. For semi-finishing and fine grinding, medium-concentration (about 75%) grinding wheels are generally used.

      The width of the grinding wheel has a great influence on the radial component force of grinding, and the radial component force Fy (the force in the radial direction of the workpiece) is easy to cause vibration, which is unfavorable for the processing quality and the durability of the grinding wheel. Therefore, in When grinding the thermal spray coating, under the condition that the strength of the grinding wheel allows, the narrow grinding wheel should be selected as much as possible, and its width should be about 10% of the diameter of the grinding wheel.

     The structure of the grinding wheel reflects the proportional relationship between the abrasive grains, the adhesive and the pores. The structure of the grinding wheel can be divided into three categories: tight, medium and loose. No. 0 ~ No. 12 and 13. The function of the grinding wheel structure is mainly to accommodate chips. The loose structure indicates that the grinding wheel has a large chip holding space, and the grinding wheel is not easy to be "plugged". Generally, a grinding wheel with a medium structure is used. When grinding the thermal spray coating, in order to avoid the "plugging" of the grinding wheel, especially when grinding the inner circle, a loose grinding wheel (also known as a large hole grinding wheel) with a tissue number of 10 or more can be used.