GRINDING MACHINE
Department of Mechanical Engineering
University of Engineering & Technology Lahore
Machine Tools & Machining

Table of Contents:
 Grinding Machine
 Working Principle
 Specifications
 Purpose of Grinding
 Types of Grinding
 Parts of Grinding Machine
 Labelled Diagram
 Grinding Machine Operations
 Calculating Wheel Sized or Shapes
 Coolant
 Affecting Factors
 Precautions

Grinding Machine
 The grinding machine is a kind of tool which is used for
grinding work pieces.
 Grinding machine it makes use of an abrasive wheel in
the form of a cutting tool.
 The rough surface of the abrasive wheel shreds away
small pieces of the work piece as needed. Each grain of
abrasive on the wheel's surface cuts a small chip from
the workpiece via shear deformation.

Working Principle
 Work piece is fed against the rotating abrasive wheel. Due
to action of rubbing or friction between the abrasive
particles and work piece material is removed.

Specifications
 Grinding wheels (super abrasive wheels) can be applied to
various specifications by combining
1. abrasive grain (abrasive grain type)
2. grain size (abrasive grain size)
3. bond strength
4. degree of concentration (grain concentration in bond)
5. bond type (bonding material).

Purpose of Grinding
 To keep the working tool in proper conditions and reduce
costs of the purchase of a new tool
 The working tool is in fact any cutting tools including
knives, scissors, joiner´s and other tools having similar
properties and functions.
 Grinding systems of this type have to be of good quality,
reliable and easily operable.

Types of Grinding
 There are four major types of grinding machine;
1. Surface Grinding
2. Cylindrical Grinding
3. Centerless Grinder
4. Tool & Cutter Grinder

Types of Grinding | 1: Surface Grinder
 The surface grinding machine is used for
grinding flat surfaces.
 The workpiece is supported on a
rectangular table which moves back and
forth and reciprocates beneath the
grinding wheel.
 A surface grinder consists of an abrasive
wheel, a chuck (a workpiece holding
device), and a rotary table.
 The chuck is used to hold the material in
place while the wheel and object are
rotated to produce a smooth finish.

Types of Grinding | 2: Cylindrical Grinder
 A cylindrical grinder is used for shaping the outside of a workpiece.
 These machines accept workpieces in a variety of shapes as long as they
can be rotated through a central axis.
 In a cylindrical grinder, both the workpiece and grinding wheel are
simultaneously rotated.
 Outside diameter grinders, internal diameter grinders, and centerless
grinders are all types of cylindrical grinders.

Types of Grinding | 3: Centreless Grinder
 A centerless grinder is a type of cylindrical
grinder which uses two rotary wheels to
secure the workpiece in place.
 Unlike a centered grinder, a centerless
grinder does not make use of a spindle.
 The speed of the rotation of the wheels
determines at what rate the material is
removed.

Types of Grinding | 4: Tool & Cutter Grinder
 A tool and cutter grinder makes use of a
CNC machine tool with up to 5 axes and
multiple grinding wheels.
 These devices are used for sharpening and
producing milling cutters such as drills,
endmills, and step tools.
 It is also widely used for producing the tools
needed in the woodworking and metal
cutting industries.

Parts of Grinding Machine:
 A grinding machine consists of following parts:
1. Base or Bed
2. Tables
3. Headstock
4. Tailstock
5. Wheel head
6. Crossfeed

Grinding Labelled Diagram

Standard types of Grinding Wheels:
 Grinding wheels come in many different
sizes, shapes, and abrasives. Some off
the various types are listed below
1. Straight
2. Cylinder
3. Tapered
4. Straight Cup
5. Flaring Cup
6. Dish
7. Saucer

Standard shapes of Grinding Wheels Faces:
 Following figure illustrates standard
shapes of grinding wheel faces.
 The nature of the work dictates the
shape of the face to be used.
 For instance, shape A is commonly used
for straight cylindrical grinding and
shape E for grinding threads.

Grinding Machine Operations:
 Some Grinding operations are discussed in the following:
1. Surface Grinding Operation:
It is used to make a flat surface, the rotating grinding wheel removes the
material from the top surface of the work-piece gives a flat look.
2. Cylindrical Grinding Operation:
This type of grinding operation is performed only for cylindrical jobs.
The cylindrical grinding operation is two types:
External cylinder grinding
Internal Cylinder grinding

Grinding Machine Operations:
3. External Cylinder Grinding Operation:
When we need to remove the excess material from the outer surface of
the work-piece then we performed an external grinding operation.
4. Internal Cylindrical Grinding Operation:
This operation is done for smoothening the internal surface of a hole
or any cylindrical work-piece.

Grinding Machine Operations:
5. Centerless Grinding Operation:
 In this type of grinding operation two grinding wheels are fitted
parallel with a little 5-10 degree angle, this angle is provided to get a
longitudinal motion of the work-piece.
 A cylindrical rod is entered between the two grinding wheel due to the
tilted angle the work-piece is automatically pass through the wheels,
and we got a smooth surface.
6. Form Grinding Operation:
 In this type of grinding process, the grinding wheel is maintained
exactly the same shape as the final product.
 When the job is passing through it automatically the pre-determined
shape is formed on the work-piece.

Grinding Machine Operations:
7. Wet and Dry Grinding Operation:
Although there are two methods of doing a grinding operation, one is
wet grinding and the second one is dry grinding.
Wet Grinding:
In wet grinding, during the grinding operation, we sprayed
coolant generally water or any coolant to cool the surface so that the
longevity of the grinding wheel increases and also we get a fine surface
finish.
Dry Grinding:
In this type of grinding process coolant is not used. Dry grinding
is not preferable, in this process grinding wheel wear is more plus we get
an uneven surface finish.

Calculating Wheel Sized or Shape:
 Both cutting speeds in SFPM and rotational speed in RPM
must be known to determine the size wheel to be used on a
fixed-speed grinding machine. To determine the grinding
wheel size, use the following formula:

Coolants:
 Most grinding machines are equipped with coolant systems.
 The coolant is directed over the point of contact between
the grinding wheel and the work.
 This prevents distortion of the workpiece due to uneven
temperatures caused by the cutting action.
 In addition, coolant keeps the chips washed away from the
grinding wheel and point of contact, thus permitting free
cutting.

Factors Affecting the Grain Size:
Grain size to be chosen when selecting a grinding wheel
depends upon the factors described below.
The softer and more ductile the material, the coarser the grain
size.
The larger the amount of stock to be removed, the coarser the
grain size.
The finer the finish desired, the finer the grain size.

Factors Affecting the Grade of Hardness:
The factors described below will determine the proper grade of
hardness of the grinding wheel.
The harder the material, the softer the wheel.
The higher the work speed with relation to the wheel speed,
the milder the grinding action and the harder the grade should
be.
The better the condition of the grinding machine and spindle
bearings, the softer the wheel can be

Factors Affecting the Structure:
The structure or spacing of the abrasive grains of wheel depends upon
the four factors described below.
The softer, tougher, and more ductile the material, the wider the grain
spacing.
The finer the finish desired, grain spacing should be.
Surfacing operations require open structure (wide grain spacing).
Cylindrical grinding and tool and cutter grinding are best performed
with wheels of medium structure (medium grain spacing).

Safety Precautions:
 Wear goggles for all grinding machine operations.
 Check grinding wheels for cracks before mounting.
 Never operate grinding wheels at speeds in excess of the
recommended speed.
 Use proper wheel guards on all grinding machines.
 Never adjust the workpiece or work mounting devices when the
machine is operating
 Do not exceed recommended depth of cut for the grinding wheel or
machine.
 Remove workpiece from grinding wheel before turning machine off.
 On bench grinders, adjust tool rest 1/16 to 1/8 inch from the wheel.