Precision Grinding

Question 1

Answer the following in terms of the grinding process:
What is precision grinding referred to as?
What is the cutting element?
At what speeds does this process take place?
What is the work fed into?

Answer 1

Referred to as abrasive machining
Cutting element is the Grinding Wheel
Rotates at very high speeds
Work is fed into the rotating wheel

Question 2

What two components are grinding wheels made up of?

Answer 2

1. The abrasive grains or Grit

2. The Bond

Question 3

Explain the importance of bond in grinding

Answer 3

While grinding the abrasive grains become worn.
The bond should then allow these worn grains to break away.
This exposes new sharp grains underneath.
This process is known as Self Dressing.
A grinding wheel selected correctly will always self dress and cut properly

Question 4

While grinding the abrasive grains become worn.
The bond should then allow these worn grains to break away.
This exposes new sharp grains underneath.
What is this dressing process also known as?

Answer 4

self dressing

Question 5

What are the two main faults that can develop in grinding?

Answer 5

Loading and glazing

Question 6

Explain what loading is

Answer 6

Loading:
The wheel becomes loaded when small particles get lodged between the grains.
Wheel does not cut effectively.
It will cause overheating of the workpiece.
The surface finish is affected

Question 7

Explain what glazing is

Answer 7

Glazing:
The grinding wheel has a shiny appearance as the abrasive particles have lost their edge and failed to break away from the wheel. It will not cut effectively. These faults are caused by inappropriate choice of grinding wheel for the material being ground.

Question 8

What can glazed grinding cause?

Answer 8

It can cause burning of the work

Question 9

What is self dressing?

Answer 9

When abrasive grains break away from the bond to expose new grains underneath. Process continues……Abrasive grains can also break along cleavage planes to produce very sharp edges. Similar to breaking a smooth sandstone in pieces.

Question 10

What can you use to dress a wheel?

Answer 10

A diamond traversed across the wheel will correct any irregularities

Question 11

Explain the process of surface/precision grinding

Answer 11

A metal cutting process in which flat and extremely smooth surfaces are produced.
The grinding wheel rotates and the workpiece, usually held in a magnetic chuck, is fed to and fro continuously.
At the end of each stroke, the table is moved across the wheel by a small amount.
The grinding wheel can be lowered to take a new cut.