Types and causes of CBN grinding wheel blockage

Types and causes of CBN grinding wheel blockage

The types of grinding wheel blockage include embedded type, attachment type, adhesive type and hybrid type.

Embedded type is the blockage of the grinding debris embedded in the pores of the working surface of the grinding wheel. Attached blockage is a kind of blockage in which the temporary force of abrasive grains is attached to the flank surface of the abrasive grain cutting edge. Adhesive type refers to the adhesion of abrasive particles around the protruding cutting edge or on the adhesive after grinding and melting. Hybrid blockage is a collection or layered collection of the above three types in a small part.

1. Causes of blockage in embedded and attachment types

Embedded and attached blockages come from two aspects, one is external and the other is internal, involving physical reactions and many other factors.

External factors: The wear debris slides out along the front of the abrasive particles, and there are several layers of wear debris accumulated in the local area in front of the abrasive particles. Due to the high-speed rotation of the grinding wheel, an airflow vortex area is formed, and the air pressure in the vortex area is significantly reduced under the action of negative pressure so that part of the abrasive debris is attached to the back of the abrasive grains, forming an attachment blockage on the blade face of the abrasive grains. Most of the attachments are ash and particles.

The effect of electrostatic field: When the grinding wheel and the workpieces are moving relative to each other, the charge on the surface of the grinding wheel and the workpiece and the gas in the grinding area will cause a physical reaction due to the high temperature to form a small electric field. Under the action of the electric field, according to the principle of opposite sex attraction, the grinding debris with the opposite polarity to the grinding wheel is adsorbed on the working surface of the grinding wheel. With the help of the greater mechanical pressure between the grinding wheel and the workpiece, the grinding debris that has been adsorbed on the surface of the grinding wheel It can be stably inserted between the gaps on the surface of the grinding wheel.

2. Causes of adhesive blockage

During the grinding process, the grinding point temperature is as high as 1200K. Under such high temperature, the grinding debris will form a low-melting metal oxide in the air. It will be heated and melted at the high temperature in the grinding zone, covering the surface of the grinding wheel. Under the action of grinding force, it is squeezed apart, strengthened, and adhered to the raised groove surface of the workpiece surface. Through multiple random grinding, more abrasive debris will adhere around the abrasive grains, thereby forming a vicious circle, aggravating clogging until the abrasive grains break or fall off, which is a fusion bond.