Centrifugal Castings

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Centrifugal Castings:

Centrifugal Castings Presented & Prepared by MAULIK DHAMELIYA 110110119023

Castings :

Castings Metals processed by casting USE Sand casting 60% Investment casting 7% Die casting 9% Permanent mold casting 11% Centrifugal casting 7% Shell mold casting 6%

Why Centrifugal Casting ?:

Why Centrifugal Casting ? Cylinders and shapes with rotational symmetry are most commonly cast by this technique. Castings can be made in almost any length, thickness and diameter. Different wall thicknesses can be produced from the same size mold. Eliminates the need for cores.

Principal of Centrifugal Casting :

Principal of Centrifugal Casting Centrifugal casting is a method of producing casting by pouring the molten metal into a rapidly rotating mould. The metal is thrown out towards the mould face by the centrifugal force under considerable pressure. The results in better mold filling and a casting with denser grain structure, which is virtually free of porosity.

Process of Centrifugal Casting :

The Mould wall is coated with a refractory ceramic coating (applying Ceramic Slurry , spinning, dying , baking). Starting rotation of the mould at a pre determined speed. Pouring of Molten metal directly into the mould (no gating system is employed). The mould is stopped after the casting has been solidified. Extraction of the casting from the mould. Process of Centrifugal Casting

Types of centrifugal casting :

Types of centrifugal casting According to the shape of the mold, the centrifugal casting method can be classified as: True centrifugal casting Semi Centrifugal casting Centrifuge casting.

True Centrifugal Casting:

True Centrifugal Casting True centrifugal castings are produced by pouring molten metal into the cavity of a rapidly rotating metal mold to whose walls the metal is thrown centrifugal force and where it solidifies in the form of a hollow casting .

PowerPoint Presentation:

True centrifugal casting is the production of hollow casting The speed of rotation and metal pouring rate vary with the alloy and size and shape being cast spin the mould may have either a horizontal or a vertical axis of rotation

Vertical True Centrifugal Casting:

Vertical True Centrifugal Casting For short casting the rotational axis vertical is chose. In the vertical axis machine the central hole will not be completely cylindrical, but will be slightly paraboloidal , which will need machining after the casting is made

Vertical True Centrifugal Casting:

Vertical True Centrifugal Casting

Horizontal True Centrifugal Casting:

Horizontal True Centrifugal Casting The pouring through travels horizontally, while the spinning mold is stationary. The ladle is stationary and the mold travels.

Horizontal True Centrifugal Casting:

Horizontal True Centrifugal Casting

Semi Centrifugal Casting:

Semi Centrifugal Casting In the Semi Centrifugal Casting process the mold is rotated around its symmetry axis The main difference is that in semi centrifugal casting the mold is filled completely with molten metal. Castings manufactured by this process will possess rotational symmetry. The centrifugal force is put to good use for the processes of slag separation

Semi Centrifugal Casting:

Semi Centrifugal Casting Gear blanks, sheaves, wheels and the pulley are the commonly produced parts by Semi Centrifugal Casting process.

Semi Centrifugal Casting:

Semi Centrifugal Casting

PowerPoint Presentation:

Centrifuge casting is different in that castings centrifuge casting process no need of rotational symmetry. The mold cavity usually fills completely and cast parts with thin walled sections are possible Great surfaces can be produced by centrifugal casting The axis of casting and the axis of rotation do not coincide with one another. Centrifuge Casting

Centrifuge Casting:

Centrifuge Casting

Characteristics of Centrifugal Casting:

The casting is relatively free from defects. Non metallic impurities which segregate toward the bore can be machined off. Less loss of metal in tundish compared to that in gating and risering in conventional and sand casting. Better mechanical properties. Production rate is high. Can be employed to manufacture bimetallic pipes. Centrifugal casting process can be used for fabricating functionally gradient metal matrix composite material. Characteristics of Centrifugal Casting

Defects in Centrifugal Casting:

Conventional static casting defects like internal shrinkage, gas porosity and nonmetallic inclusions are less likely to occur in centrifugal casting. Hot Tears – Hot tears are developed in centrifugal castings for which the highest rotation speeds are used. Longitudinal tears occur when contraction of casting combined with the expansion of the mould, generates hoop stresses exceeding the cohesive strength of the metal at temperatures in the solidus region. Defects in Centrifugal Casting

Defects in Centrifugal Casting:

Segregation - Centrifugal castings are under various forms of segregation thus pushing less dense constituents at centre. Banding – Sometimes castings produce zones of segregated low melting point constituents such as eutectic phases and sulphide and oxide inclusions. Various theories explain this, one states vibration is the main cause of banding. Defects in Centrifugal Casting

Some Centrifugal Castings:

Some Centrifugal Castings

Application of Centrifugal Casting:

Pipes for water gas sewage. Bearing Bushes. Cylinder Liners. Piston rings Paper making rollers Clutch Plates. Pulleys. Application of Centrifugal Casting

Thank you:

Thank you

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