3 Factors to Note in Choosing CBN Grinding Wheels

Selection of CBn coolant

How to choose the coolant for CBN grinding wheels is an important topic in the field of super hard grinding.
In the process of grinding workpieces, the choice of coolant not only plays an important role in the quality of product grinding but also has a greater impact on the cost of production and processing.

In which areas is the power of the CBN grinding wheel spindle motor mainly consumed?

• grinding process
• grinding wheel drive
• Coolant transfer

In order to prevent changes in the material phase due to local and gradual high temperatures, the high temperatures generated by grinding must be cooled in time during the workpiece grinding process. This is due to the fact that changes in the material phase usually result in the formation of a white layer and the involvement of stresses, which can significantly reduce the service life of the material and indicate the appearance of cracks.
The coolant cools and moistens the contact area. Usually the stronger the CBN grinding wheel is in reducing resistance, the more coolant it absorbs. The deposits left on the grinding wheel will affect the dimensional accuracy of the wheel, for this reason, we must carry out timely cleaning of the residue to ensure the neatness of the grinding wheel surface.

How to choose CBN grinding wheel coolant?

Choosing a CBN wheel coolant with suitable parameters can minimize the high temperature generated by high-speed grinding in order to achieve the effect of grinding wheel cooling.
The high temperature generated in high-speed grinding requires cooling, and the amount of coolant flow is related to the type of grinding wheel selected for grinding the workpiece.
In most cases, the time consumed by the coolant injector is very close to the time the grinding machine is running. In other cases, CNC grinder manufacturers make a very simple nozzle device with a small diameter bent metal tube as a reference, which is more common on tool grinders.

Characteristics of cbn grinding wheels

Now the grinding market is used to grind difficult or hard materials, are selected cbn grinding wheel grinding, which is inseparable from the characteristics of cbn grinding wheel selected grinding grain.

1, cbn grinding wheel grinding high-temperature resistance

As the speed of cbn grinding wheel grinding is very high, so the heat generated is also very large, so stability is very important. CBN abrasive stability is very high, after experiments have shown that cbn abrasive grain under normal air pressure, at a high temperature of 1300 ℃ is not oxidation reaction, so cbn grinding wheel can withstand very high processing temperature.

2, cbn grinding wheel grinding thermal conductivity

Thermal conductivity is also an important reason for choosing cbn grinding wheels, because even if the grinding wheel can withstand a very high temperature, but the workpiece can withstand a limited temperature, so the thermal conductivity is also one of the important reasons for our choice of grinding wheels, and the thermal conductivity of cbn abrasives is very high, the use of cbn grinding wheels for grinding work in the same grinding volume, the heat generated is reduced very significantly.

3. Through the above two characteristics we can also think of a corollary that can enhance productivity, because good thermal conductivity and high temperature resistance can allow cbn grinding wheels to grind at high speed and with large removal without burning the workpiece. In the premise of ensuring and even improving quality greatly accelerates the work efficiency.

Equipment requirements for applicable ceramic cbn grinding wheels

1、The rigidity of the grinding machine
Since cbn abrasives are hard, the force on the grinding wheel shaft during grinding is much greater than that of an ordinary grinding wheel, so the grinding machine is required to have greater rigidity than an ordinary grinding wheel, generally requiring more than 50% of the grinding wheel.

2. The grinding machine should have a higher linear speed and better shock resistance
The high hardness of cbn grinding wheels allows for greater depth of cut than ordinary grinding wheels. If the grinding wheel line speed is increased, the contact time between the grinding grain and the workpiece will be shortened, so that the grinding force will be reduced, while the surface roughness value of the workpiece will be reduced accordingly, generally requiring a grinding wheel line speed of 60m/s or more. The higher the wheel speed is, the smaller the ratio of the accumulated cross-sectional area per unit perimeter of the grinding wheel to the change in surface roughness; the higher the wheel speed is, the better the surface quality of the workpiece will be.
In addition, the grinding wheel should have good vibration resistance when rotating at high speed, so as to ensure high quality of the grinding workpiece and good safety.

3. Dressing conditions and dressing accuracy of the grinding machine
cbn grinding wheel must use diamond roller dressing, not only because the diamond roller dressing efficiency, strong forming ability, dressing surface precision stability, and for large specifications cbn grinding wheel because of the diamond pen, knife, etc. in the dressing wear, resulting in grinding wheel may not repair flat. cbn grinding wheel dressing feed depth requirements are very high, because cbn abrasive is more expensive, more repair 0.01㎜ will cause great It is generally required to be less than 0.005mm/time feed depth.
In addition, it also requires high precision of grinding wheel spindle and good sealing of machine tool, especially the headstock and bearing part of machine tool.