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Questions and Answers
What is the main purpose of grinding in the context of this text?
What is the main purpose of grinding in the context of this text?
Which type of grinding machines are used to remove stock with no reference to accuracy of results?
Which type of grinding machines are used to remove stock with no reference to accuracy of results?
What is the accuracy of the grinding process mentioned in the text?
What is the accuracy of the grinding process mentioned in the text?
Which type of grinding machine is used to finish parts to very accurate dimensions?
Which type of grinding machine is used to finish parts to very accurate dimensions?
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What are the main types of precision grinders mentioned in the text?
What are the main types of precision grinders mentioned in the text?
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Which type of grinding machine is used to remove excess metal from cast parts and welded joints?
Which type of grinding machine is used to remove excess metal from cast parts and welded joints?
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What is the primary function of cylindrical grinders?
What is the primary function of cylindrical grinders?
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Which type of surface grinding machine leaves a criss-cross pattern of grinding scratches on the work surface?
Which type of surface grinding machine leaves a criss-cross pattern of grinding scratches on the work surface?
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What is the purpose of the taper grinding operation?
What is the purpose of the taper grinding operation?
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Which type of grinding is performed by mounting and rotating the work between centers?
Which type of grinding is performed by mounting and rotating the work between centers?
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What is the main function of gear grinding machines?
What is the main function of gear grinding machines?
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How are threads ground accurately using thread grinding machines?
How are threads ground accurately using thread grinding machines?
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What classifies a grinding wheel under the 'mounted grinding wheels' category?
What classifies a grinding wheel under the 'mounted grinding wheels' category?
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What distinguishes artificial abrasives from natural abrasives?
What distinguishes artificial abrasives from natural abrasives?
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Which abrasive is used for grinding softer materials only?
Which abrasive is used for grinding softer materials only?
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What is the main purpose of using abrasives in grinding and polishing operations?
What is the main purpose of using abrasives in grinding and polishing operations?
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Which natural abrasive contains a greater percentage of aluminium oxide than emery?
Which natural abrasive contains a greater percentage of aluminium oxide than emery?
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Which natural abrasive is used in making grinding wheels to grind cemented carbide tools?
Which natural abrasive is used in making grinding wheels to grind cemented carbide tools?
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Which artificial abrasive is next to diamond in terms of hardness?
Which artificial abrasive is next to diamond in terms of hardness?
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Which artificial abrasive is better adapted to grinding materials of high tensile strength?
Which artificial abrasive is better adapted to grinding materials of high tensile strength?
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What does the grade of a grinding wheel refer to?
What does the grade of a grinding wheel refer to?
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What is the structure of a grinding wheel referring to?
What is the structure of a grinding wheel referring to?
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How is the grain size or grit number of a grinding wheel denoted?
How is the grain size or grit number of a grinding wheel denoted?
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'Green grit' and 'black grit' are types associated with which artificial abrasive?
'Green grit' and 'black grit' are types associated with which artificial abrasive?
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'A' is the designation for which type of artificial abrasive?
'A' is the designation for which type of artificial abrasive?
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'S' is used as a symbol for which artificial abrasive type?
'S' is used as a symbol for which artificial abrasive type?
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Study Notes
Grinding Machine
- Grinding is a metal cutting operation that removes metal in small volumes, using an abrasive wheel with many cutting edges.
- The machine on which grinding operation is performed is called a grinding machine.
- Grinding is done to obtain high dimensional accuracy and better appearance.
- The accuracy of grinding process is 0.000025mm.
Types of Grinding Machines
- Classified into two types: rough grinding machines and precision grinding machines.
- Rough grinding machines are used to remove stock without reference to accuracy.
- Main types of rough grinders: hand grinding machine, bench grinding machine, floor stands grinding machine, flexible shaft grinding machine, swing frame grinding machine, and abrasive belt grinding machine.
- Precision grinding machines are used to finish parts to accurate dimensions.
- Main types of precision grinders: cylindrical grinding machines, internal grinding machines, surface grinding machines, tool and cutter grinding machines, and special grinding machines.
Cylindrical Grinding Machines
- Used to grind external surfaces like cylinders, taper cylinders, faces, and shoulders of work.
- Two types: external cylindrical grinding machines and internal cylindrical grinding machines.
Surface Grinding Machines
- Used to finish plain or flat surfaces horizontally, vertically, or at any angle.
- Four types: horizontal spindle and reciprocating table type, horizontal spindle and rotary table type, vertical spindle and reciprocating table type, and vertical spindle and rotary table type.
Grinding Machine Operations
- Operations performed in a grinding machine: cylindrical grinding, taper grinding, gear grinding, thread grinding, and surface grinding.
- Cylindrical grinding: performed by mounting and rotating the work between centres in a cylindrical grinding machine.
- Taper grinding: done on long workpieces by swivelling the upper table.
- Gear grinding: done by generating process or using a form grinding wheel.
- Thread grinding: uses a grinding wheel shaped to the thread profile.
Grinding Wheel
- A multi-tooth cutter made up of many hard particles (abrasives) with sharp edges.
- Classified into three categories: solid grinding wheels, segmented grinding wheels, and mounted grinding wheels.
- Abrasives: used for grinding and polishing operations, having uniform physical properties of hardness, toughness, and resistance to fracture.
Abrasives
- Classified into two principal groups: natural abrasives and artificial abrasives.
- Natural abrasives: obtained from the Earth's crust, including sandstone, emery, corundum, and diamond.
- Artificial abrasives: silicon carbide abrasives and aluminium oxide abrasives.
Artificial Abrasives
- Silicon carbide: manufactured from silica, powdered coke, salt, and sawdust, used for grinding materials of low tensile strength.
- Aluminium oxide: manufactured from mineral bauxite, silica, iron oxide, titanium oxide, etc., used for grinding materials of high tensile strength.
Types of Bonds
- A bond is an adhesive substance that holds abrasive grains together in the form of grinding wheels.
- Different grinding wheels are manufactured by mixing hard abrasives with suitable bonds.
- Types of bonds: various, including vitrified, silicate, shellac, and resinoid.
Grain Size, Grade, and Structure
- Grain size (Grit): indicates the size of the abrasive grains used in making a wheel, or the size of the cutting teeth.
- Grade: refers to the hardness with which the wheel holds the abrasive grains in place.
- Structure: the relative spacing occupied by the abrasives and the bond, denoted by the number and size of void spaces between grains.
Standard Marking System of Grinding Wheels
- The Indian standard marking system for grinding wheels has been prepared to establish a uniform system of marking.
- The marking system includes: prefix, manufacturer's abrasive type symbol, type of abrasive, size of abrasive, grade of bond, structure of the grinding wheel, and type of bond.
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Description
Test your knowledge on the introduction to the grinding process and grinding machines. Learn about the operations and importance of grinding for achieving high dimensional accuracy and appearance in metal cutting. Explore the details of abrasive wheels and material removal in grinding.
