Presentation on Grinding and Grinding wheel specification

Grinding is comman surface finishing process used to finish the part to the required size and to maintain the surface texture

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: Natural Abrasives Artificial Abrasives (Manufactured Abrasives)

5. APPLICATIONS OF NATURAL ABRASIVES 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