The document discusses different types of grinding machines and their processes. It describes grinding as an abrasive machining process that uses a revolving wheel to cut hard materials. There are different types of grinding machines based on the geometry of the workpiece, such as surface grinding for flat surfaces, cylindrical grinding for external cylindrical surfaces, and centerless grinding which does not use centers or fixtures to hold the workpiece. The document provides details on grinding wheels, abrasives, and factors to consider for selecting the appropriate grinding wheel for different materials and processes.

1. Topic- Grinding Machines
Subject-Manufacturing Processes-1
Guided by- Alpesh Joshi sir
By- Diparsh Modh(141043119002)

2. GRINDING MACHINES
Grinding is an abrasive machining process done with the help of a
revolving wheel mounted on a suitable Machine. Abrasive
machining processes are used under one or more of the following
conditions:-
1. The material to be cut is too hard for other machining processes.
2. The surface finish desired is superior to what can be obtained
with other methods.
3. The dimensional accuracy requirements are too stringent for
other processes.

3. Two characteristics features of the abrasive machining processes are that
a very large number of cutting edges may be simultaneously machining a
given surface, each taking a minute of cut of its own and that the
geometry and orientation of these cutting edges at any given instance are
completely random.
• It is the only economical method of cutting hard material like
hardened steel.
• It produces very smooth surface , suitable for bearing surface.
• Surface pressure is minimum in grinding. It is suitable for light
work,which will spring away from the cutting tool in the other
machining processes.

4. Grinding Process

5. ABRASIVES
Abrasives are hard substances with adequate toughness capable of
machining materials too hard to be cut by most other tool materials.
They can also produce better surface finish and closer dimensional
tolerances on most materials. They can be used in the machining processes
as loose grains, in the form of grinding wheels and sticks or as coatings
depending upon the type of operation.
TYPES OFABRASIVES
1. Natural Abrasives
2. Artificial Abrasives

6. Types of abrasives

9. GRAIN SIZE
The number indicating the size of the grit represents the number of
openings in the sieve used to size the grain. The larger the grit size number
, the finer the grit.
GRADE
• Grade indicates the strength of the bond and, therefore, the `hardness`
of the wheel.
• In a hard wheel the bond is strong and it securely anchor the grit in
place, and therefore, reduces the rate of wear.
• In a soft wheel, the bond is weak and the grit is easily detached
resulting in a high rate of wear.
STRUCTURE
This indicates the amount of bond present between the individual abrasive
grains, and the closeness of the individual grain to each other. An open
structured wheel will cut more freely. That is, it will remove more metal.
In a given time and produce less heat.

10. BOND
•Vitrified bond (V)
•Silicate bond (S)
•Shellac bond (E)
•Rubber bond (R)
•Resinoid bond (B)
SELECTION OF GRINDING WHEEL
For grinding a job the right grinding wheel is to be selected. The selection of
a grinding wheel will depend on the following factors.
•Material to be ground
•Amount of stock to be removed
•Finish required
•Area of contact
•Wheel speed
•Work speed
•Personal factor
•Method of cooling

11. Type of grit used for grinding

12. DEPTH OF CUT
• It is the thickness of the material removed in surface grinding for one cut.
• Depth of cut in grinding depend on the:
• Cutting load
• Power of the machine
• Finish required

13. WORK SPEED
CLASS OF WORK ROUGH
GRIND m/min.
FINISH GRIND
m/min.
Soft steel 10-20 20-25
Hardened steel 25-30 30-40
Cast iron 35-55 45-65
Aluminium and fine
brass
50-65 50-65

14. GRINDING WHEEL DRESSING &TRUING
• Dressing refers to the removing of clogs and blunt abrasive grains from
the surface of the grinding wheel. Dressing exposes the cutting edges
which restore the correct cutting action of the wheel. Dressing is done on
a glazed or loaded wheel to recondition it.
• Truing refers to the shaping of the wheel to make it run concentric with
the axis. When a new grinding wheel is mounted, it must be trued before
use to remove the run out.
GLAZING & LOADING
• When the surface of a grinding wheel develops a smooth and shining
appearance, it is said to be glazed. This indicate the abrasive particles on
the wheel face are not sharp. These are worked down to bond level.
• When soft materials like aluminium, copper, lead, etc. are ground the
metal particles get clogged between the abrasive particles. This condition
is called loading.

15. Grinding wheel specification system

16. Grinding wheel specification

17. Common Grinding wheels

18. Surface Grinding
• It is precision grinding machine to produce flat surface on a workpiece. It
is a more economical and more practical method of accurately finishing
flat surface than filling and scraping.
TYPES OF SURFACE GRINDERS
• Horizonal spindle reciprocating table
• Horizontal spindle rotary table
• Vertical spindle reciprocating table
• Vertical spindle rotary table

19. Cylindrical Grinding

20. Centre less Grinding

21. Types of centerless Grinding
• Internal Grinding
• Centerless Grinding

22. Centerless Grinding Machine
• A Centerless grinding machine as the name suggests has no centers, drivers
and other fixtures required for holding the workpiece.
• It is used for grinding external cylindrical surfaces, tapers and forms with
rotational symmetry.
• The essential units of the machine are the grinding wheel, the regulating
wheel, the work rest blade and the slide.
• The regulating wheel and work rest blade support the work piece.
• The regulating wheel also controls the speed and feed of the workpiece. It is
made up of a rubber bonded abrasive material with enough friction to provide
a good grip on the surface of the workpiece sot that the workpiece rotates
with the surface speed of the regulating wheel. The regulating wheel is
mounted on a slide so that its axis of rotation can be moved towards or away
from the work rest table.
• The work rest blade and the regulating wheel slide are mounted yet on
another slide which is moved towards the grinding wheel for depth motion or
in feed.

23. Advantages of Centerless Grinding
• Due to shorter loading times, actual grinding time is decreased compared
with other methods of grinding. Once the centerless grinder has been
properly set-up for a particular run, no further adjustment or additional
set-ups are needed as opposed to centertype (cylindrical) grinding.
• This alone offers substantial savings. The workpiece is under constant,
rigid support while in the grinding mode, making it feasible to take
heavier cuts and grind fine pins, rods and wires.
• When grinding easily distorted workpieces, the centerless grinder is most
advantageous because of its lack of axial thrust. Automatic feeding offers
continuous production of large quantities of smaller size workpieces.
• Centerless machines are designed for simplicity which in itself cuts
down on machine maintenance
Thank you……