The document focuses on grinding as a metal removal process using various natural and manufactured abrasives. It details applications and properties of several abrasives, including emery, garnet, silicon carbide, and aluminium oxide, highlighting their effectiveness in different grinding operations. Additionally, the document references educational materials and content developers involved in its creation.

1. Department of Collegiate and Technical Education
GRINDING (Week 3)
Session-I
Course Outcome : CO2
MACHINE TOOL TECHNOLOGY
( IIIrd Semester)
Mechanical Engineering
Mechanical Engineering – 20ME32P

2. Grinding
Abrasives, Applications of Natural abrasives:
• Emery
• Garnet
• Sand Stone/Solid Quartz
Applications of Manufactured (Artificial) abrasives:
• Silicon Carbide
• Aluminium Oxide
Contents
•Corundum
• Natural Diamond
•Cubic Boron Nitride

3. GRINDING
• Grinding is a metal removal process performed by means of a
rotating wheel that acts as a tool. It is used to finish work pieces,
which must show a higher surface finish, accuracy of shape and
dimensions.
• Mostly grinding is the finishing operation because it removes
comparatively little metal i.e. 0.25 to 0.50mm in most operations
and the accuracy in dimensions is in the order of 0.000025mm.
Grinding is also done to machine materials, which are too hard by
other machining methods

4. ABRASIVES
• Abrasives are the substances that are used for grinding and
polishing operations. Abrasives should be pure and have uniform
physical properties of hardness, toughness and resistance to fracture
and to be useful in the manufacture of grinding wheels.
• Abrasives may be classified into two principal groups:
1. Natural Abrasives
2. Artificial Abrasives (Manufactured Abrasives)

5. APPLICATIONS OF NATURALABRASIVES
1. Emery: -
• It is a very hard and fracture resistant rock. It is a compound of
corundum (Aluminum oxide) mixed with some traces of spinels
containing iron, herbite, magnetite and titanium.
• This is used in metal cutting and polishing tools. Some very
fine grains can also be used for very technical polishing such as
the preparation of metallurgical samples that require very strict
tolerances.

6. Contd.,
2. Garnet: -
• These are a family of minerals that are classified as natural
silicate minerals. Their diverse properties from light
transmission, as gems to the opaque varieties of these make
them used for various industrial purposes.
•They are used as abrasives because of their resistance to
sanding wood and other materials. In addition due to its
magnetic properties it is used to identify jewelry

7. Contd.,
3. Sand Stone/Solid Quartz: -
• It is one of the most important natural abrasive stone found
in large quantities in all the earth’s crust. It is the most used
abrasive because of its low price. It is used in the manufacture
of sand papers, discs or blocks and mainly in pressure blasting
systems

8. Contd.,
4. Corundum: -
• It is a natural mineral that forms crystalline and trigonal
rocks of aluminum oxide. It is commonly used as an abrasive
in everything from sandpaper to large tools that are used in
machining of metals, plastics and wood

9. Contd.,
5. Natural Diamond: -
• It is one of the quintessential abrasive that is the hardest
natural material known. The uses of Natural diamond as an
abrasive are numerous and varied in industry from cutting,
polishing and refining other materials such as glass, ceramics,
stone and tungsten carbide. The industrial cost of diamond is
very high.

10. Applications of Manufactured Abrasives
1. Silicon Carbide: -
• There are two types of silicon carbide abrasives (a) Green grit
which contains 97% Silicon carbide and (b) Black grit which
contains 95% silicon carbide. Silicon carbide follows the
diamond in order of hardness, but is not tough as aluminium
oxide. It is used for grinding materials of low tensile strength
such as cemented carbides, stones and ceramic materials, gray
cast iron, vulcanized rubber, brass, bronze, copper etc.,

11. Contd.,
2. Aluminium Oxide: -
• It is tough and not easily fractured, so it is better adopted to
grinding materials of high tensile strength such as carbon
steels, annealed malleable iron, wrought iron, tough bronzes,
high speed steels etc.,

12. Contd.,
3. Cubic Boron Nitride: -
• It is the second hardest material and is widely used for
grinding steels. CBN is increasingly replacing conventional
abrasives for precision grinding of hardened steels due to its
low rate of wear and the ability to hold close tolerance on the
parts produced

13. REFERENCES
•Elements of Workshop Technology (Vols. 1 and II) by Hajra Chaudhary.
•Production Technology By R.K. Jain
•Foundry Technology By O.P.Khanna
•Engineering Drawing Vol-2 By K.R.Gopala Krishna
•Engineering Drawing By N.D.Bhat

14. Thank you
Content Developers
•Shri. Nataraj Kuntoji, GPT Bagalkote / 152
•Shri. H.B.Goudar, GPT Bagalkote /152
•Shri. Shivakumar Pujeri, GPT Bagalkote /152
•Shri. Hanamant.B.Teggi, GPT Bagalkote /152