Abrasive Grinding Defects. Hazards Related to Abrasive Grinding Wheels

Introduction

As we know from the study of the process of abrasive grinding that it is basically a process of metal removal through abrasive action. Needless to say, such a procedure would surely result in the production of sufficient quantities of heat. Hence it is very important to study the effect of heat during the grinding process in order to have an idea of the thermal effects involved. These effects can be studied from two perspectives - the effect on the grinding wheel and the effect on the work piece itself. Apart from heat there are other types of defects as well which could arise during the process of grinding. All these have been dealt with in the sections below

Defects in Grinding

We will first study the thermal effects of grinding and these can be covered under two headings namely effects of the wheel and that on the work piece respectively as shown below.

Grinding wheel thermal effects

The main effect of heat on the grinding wheel is the development of the cracks known as grinding cracks. These cracks appear in a direction that is at right angles to the grinding marks. Obviously if these cracks are present in too large a number, the grinding wheel would need to be replaced.

Work piece thermal effects

The work piece is more affected by the heat mainly because it retains a larger proportion of the heat generated during the grinding operation. The work piece can get damaged in various ways including some or all of the following.

There could be certain reactions which take place at the high-temperatures attained during grinding. These reactions could result in minor changes such as discolouration of the surface due to oxide production, or there could be more serious chemical damage to the work piece.

The material properties of the work piece might change due to the application of sudden heat during the process. The material could become brittle or it could get scratched due to ultra-sharp abrasive material.

One of the solutions if the work piece is getting overheated is to change the grinding wheel with another wheel which is made up of relatively softer material.

Other Problems and safety measures

• Apart from thermal heating there are several other problems which may arise during the process of grinding. For example the grinding wheel might be wearing too soon and this can be rectified through the use of harder wheel so that its relative hardness is much more compared to the work piece.

• If the finishing of the work piece is not coming oun as desired, that means that there is certainly a matter with the structure of the wheel and it needs to be changed to either a coarse wheel or a finer wheel depending on which problem is arising.

• If the grinding wheel is not properly balanced, that can also lead to problems such as chatter marks.

• Normally an operator would check a wheel thoroughly before actually mounting it on the machine. The mounting should be perfect and proper guard should be there over the wheel to prevent injury to the operator.