Grinding 23

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Grinding
Grinding is a surface finishing operation where very thin layer of material is removed in the form of dust particles.Thickness of material removed is in range of 0.25 to 0.50 mm.Tool used is a abrasive wheel.

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Abrasives
Abrasive is the material employed for sharpening, grinding and polishing operations.Natural abrasive emery, corundum, quartz, sandstone, diamond, etc.Artificial abrasive carborundum, aloxite, alundum, etc.

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Applications of abrasives
Corundum : is a natural mineral which consists of aluminium oxide. Hardest natural substance after diamond. Used for shaping, finishing and polishing other tools.Emery : natural abrasive consisting of aluminium oxide and little amount of iron oxide.Silicon carbide : synthetic abrasive harder than aluminium oxide.Used to grind metals like iron, brass and soft bronze.Used in non metals like wood and leather industries.

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Zirconia aluminia : it is a mixture of zirconium oxide and aluminium oxide.Used in casting and foundry industries.Cubic boron nitride : is made up of boron nitride with a cubic crystalline structure. Used for hard coating material. Diamond :

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Bonding materials
These are adhesives which holds the abrasive grains together.Vitrified process : Silicate process :Elastic process :Rubber or vulcanite process :

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Grinding machines
Grinding machine is a power operated machine tool where, the work piece is fed against constantly rotating abrasive wheel to remove thin layer of material from work.

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Principle of grinding machines
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.

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Classification of grinding machine
Bench grinding machineSurface grinding machineCylindrical grinding machineCenter less grinding machineInternal grinding machineSpecial purpose grinding machine

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Surface grinding machine
It is machine basically used to grind flat surface.Job is mounted to a table which moves longitudinally as well as in transverse direction.Manual feed or power feed.Work piece can clamped in two waysManual clamps.Magnetic chuck.

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Internal pump and piping arrangement for coolant.Protective guard for safety.

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Base ColumnTable traverse and vertical feed hand wheel.Wheel guard and protective guard.

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Working Work piece is clamped to the table by operating magnetic chuck.Required grade of grinding tool is fixed to spindle.Grinding operation is carried out be operating both table traverse wheel and vertical feed hand wheel.

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Cylindrical grinding machine
It is a process of grinding curved surfaces.Surface may be straight or tapered. Work piece is mounted on two centers, one is tailstock centre and the other is headstock centre. Head stock center may or may not revolve.

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Centre less grinding machine
It is used to grind curved surface work piece which are long and slender.Work piece rests on a work-rest blade and is backed by a second wheel called as regulating wheel.Grinding wheel pushes the work piece down the work-rest blade against the regulating wheel.

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Documents

Grinding 23