Grinding Wheel:Material,Bond,Grain size,Grade,Specification,Types

Hello all in this topic, we cover Grinding wheel in which we know in detail grinding wheel's material, bond, grain or grit size, grade, structure, Types, defects and also we know how to read specification of grinding wheel.

Grinding wheel is the part of Grinding Process and grinding process is the part of manufacturing process.

Grinding wheel play most important role in grinding process.

It is fitted with different types of grinding machine like surface grinding machine, tool and cutter grinding machine, centerless grinding, cylindrical grinding machine, etc and then perform.

The grinding wheel is used for finishing and also used for ferrous and non ferrous metal cutting process.

The objective of studying this topic is to make you able to know, how to create excellent quality of surface finish, imparting high quality of accuracy of shape and dimensions, sharpening of cutting edges of cutting tools, finishing of cast and welded surface and many more.

So, firstly lets know about grinding process which is done by grinding wheel.

Grinding Process

In this process cutting the metal that means grinding is used to remove unwanted material and provide finishing.
In grinding, metal is removed in form of chip.

grinding wheel
Grinding Process

Grinding Wheel Definition

It is a type of cutting tool, which is used in the grinding operation for the purpose of cutting.

Grinding Wheel Material

It is made up of two components which are given below

1. Abrasive

2. Bond/Binders

Abrasive

Abrasive particles are very tough and hard granular materials, which are used to cut the peaks present on the workpieces. 
The selection of abrasive particles depends upon the material, which is used to grind.

For measuring abrasion resistance we can use akron abrasion tester.

Grinding wheel abrasives

It is of two types which is  given below

•Natural Abrasive

•Artificial Abrasive

Natural Abrasive

The abrasive which is found in nature is known as natural abrasive.
Eg corundum, emery, diamond, etc.

Artificial Abrasive

The abrasive which is manufactured, not found freely in nature is known as artificial abrasive.

The different types of artificial abrasive are as follows

•Aluminium Oxide

•Silicon Carbide

•Artificial Diamond

Aluminium Oxide

Its particle are very hard, tough and sharp edged. It is used to grind the carbon steel, mild steel, wrought iron and die steel.
That means in Industry or factory most of aluminium oxide abrasive type Grinding wheel used.
It is denoted by A.

Silicon Carbide

The molecules of silicon carbide is brittle. Therefore, silicon carbide grinding wheel is used for low tensile strength metals to grind Like cast iron, bronze, copper, ceramic, etc.
It is denoted by C.

Artificial Diamond

The diamond made artificially is know as artificial diamond.
It is hard as natural diamond.
It is denoted by D.

Bond/Binders

Bonding is an phenomenon in which material hold strongly. In bonding many types of abrasive grains are used like silicate, shellac, rubber, metal.

Types of bond in grinding wheel

Bonding materials used for making the wheel is given below

•Vitrified Bond

•Silicate Bond

•Shellac bond

•Resin or Resinoid Bond

•Rubber Bond

•Metal Bond

•Oxychloride Bond

•Reinforced Resin Bond


Vitrified Bond

Its main constituent is felspar, which is mixed with some other refractory material to form a strong bond.
It is not affected by water, acid oils or ordinary temperature conditions.
It is denoted by letter V.

Silicate Bond

In this bond, silicate is used to bind the abrasive particles.
It is denoted by letter S.

Shellac bond

In this bond, the abrasive particles are mix with the shellac and then heated.
It is denoted by letter E.

Resin or Resinoid Bond

It is mostly used for table grinding, swing grinding, snagging grinding, cam grinding, etc.
It is denoted by letter B.

Rubber Bond

The abrasive particle is mixed with rubber and sulphur then drawn in the shape after heating.
These are used for good surface finishing. It is denoted by letter B.

Metal Bond

It is used for the grinding of very hard metal like tungsten carbide, etc.
It is denoted by letter M.

Oxychloride Bond

This is used without coolant and in file or razor blade industries.

Reinforced Resin Bond

This type of bond mostly used in manufacturing industries and denoted by BF.


Grain or Grit Size of Grinding Wheel

The size of the abrasive particle is known as grain size or grit size.

According to IS standard, grain sizes divided into four groups

(i) Coarse size

(ii) Medium size

(iii) Fine size

 (iv) Very fine size

Coarse Size

Grain size number from 10 to 24.

Medium Size

Grain size number from 30 to 60.

Fine Size

Grain size number from 80 to 190

Very Fine Size

Grain size number from 200 to 600.

Grade of Grinding Wheel

Grading is done from A to Z in grinding wheel which is given bellow

Soft Grade
Medium Grade
Hard Grade

Soft Grade

If using Soft grade grinding wheel then choose from A to H grades of the wheel.

That means soft grade grinding wheel denoted by the letter from  A, B, C, D, E ...... to H.
 

Medium Grade

If using Medium grade grinding wheel then choose from I to P grades of the wheel.

That means medium grade grinding wheel denoted by the letter from  I, J, K, L, M ...... to P.
 

Hard Grade

If using Hard grade grinding wheel then choose from Q to Z grades of the wheel.

That means hard grade grinding wheel denoted by the letter from  Q, R, S, T, U ...... to Z.
 

Structure of Grinding Wheel

The structure of the grinding wheel refers to the entity of the grinding wheel.

Here are two types of structure as

•Open Structure

•Close Structure

Open Structure

The structure in which separation is provided between the particles by using large quantity of the binder is known as open structure.

Close Structure

The structure in which separation is not provided between the particles is known as close structure.
The binder used in close structure with less quantity than the previous one.

Specification of Grinding Wheel 

To specified the grinding wheel following terms are necessary to know, which I have already discussed, So here we know how to read specification of grinding wheel.

 • Grinding Wheel Material
• Grinding wheel bonding material
• Grain or Grit Size of Grinding Wheel
• Grade of Grinding Wheel
• Structure of Grinding Wheel


grinding wheel
Grinding Wheel Specification


Now we specified grinding wheel through figure one by one

(1) In a figure shown dimension of grinding wheel  ∅105×1.2×16mm

Where,

105 – Diameter of grinding wheel

1.2 – Thickness of grinding wheel

16 – size of arbor hole

(2) In a figure of grinding wheel shown
A 46 N BF

Where,

A - It is denoted the type of abrasive where “A” means aluminium oxide.

46 – It is denoted the grain size of grinding wheel where “46” represent medium size.

N – It is defined grade of grinding wheel where “N” represent medium grade.

BF – It is defined bonding materials of grinding wheel where “BF” represent reinforced resin bond.

Types of grinding wheel

The grinding wheels are made in different shapes and operations and for use on different types of machines.

Sizes to perform different Generally, following types of grinding wheels are found

•Straight Wheel

•Tapered Wheel

•Cylindrical Wheel

•Straight Cup Wheel

•Herring cup wheel

•Dish Wheel

•Saucer Wheel

•Diamond Wheel


Straight Wheel

It is used for cylindrical, centreless and surface grinding operation.

Tapered Wheel

It is used for snagging grinding, gear tooth, etc.

Cylindrical Wheel

It is used for grinding the plain or curved surface.

Straight Cup Wheel

It is used for off hand grinding.

Herring cup wheel

It is used for sharpening the milling cutter.

Dish Wheel

It is used for grinding the slots and devices.

Saucer Wheel

It is used for grind milling cutters and twist drill.

Diamond Wheel

It is used for grinding extremely hard materials.

Grinding Processes

The following operation is performed on the grinding wheel before grinding

• Dressing of the grinding wheel

• Truing of the grinding wheel

• Balancing of the grinding wheel

• Mounting of the wheel on machine


Defects in Grinding Wheel

The defects in the grinding wheel are as follows

•Loading

•Glazing

Loading

The filling of grinded chips between the abrasive particles of the grinding wheel is called loading.

Loading is caused due to

(i) Putting workpiece by the wheel.

 (ii) Taking cuts that are too deep.

(iii) Grinding of soft material.

 (iv) By using a wheel of too hard bond and running it too slowly.

Glazing

It is that condition, in which the face or the cutting edge takes a glass like appearance.

The glazing is happening due to following reasons

(i) Using hard wheel on hard metals.

 (ii) More speed of revolution or wheel.

 (iii) Less feed of the job.


So, Here I talked about Grinding Wheel and all terms which is related to Grinding Wheel. 

Thank You.


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