MANUFACTRING TECHNOLOGY

• CENTRIFUGAL CASTING • SHELL MOULDING

CENTRIFUGAL CASTING In this process molten metal is poured in mould and

allowed to solidify while the mould is rotating. Metal is poured into the centre of the mould at its axis of rotation. Due to centrifugal force the liquid metal is thrown out towards the periphery.

PREREQIUSTIES

Mould Material

Steel Cast Iron Graphite Sand Rotation Speed of Centrifugal Mould about 1000 rpm

A Centrifugal Casting Machine.

PROCEDURE1) The Mould wall is coated with a refractory ceramic coating (applying

Ceramic Slurry , spinning, dying , baking).2) Starting rotation of the Mould at a pre determined speed.3) Pouring of Molten metal directly into the Mould (no gating system is

employed).4) The Mould is stopped after the casting has been solidified.5) Extraction of Mould from the casting.

APPLICATIONS OF CENTRIFUGAL CASTING

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

VIDEO LINK

https://www.youtube.com/watch?v=ZxVA-htTunU

SHELL MOULDING

SHELL MOULDING Shell moulding, also known as shell-mould

casting, is an expendable mould casting process that uses a resin covered sand to form the mould

PROCESS Pattern creation Mould creation Mould assembly Pouring Cooling Casting removal

PATTERN CREATION

A two piece metal pattern is created in the shape of the the desired part typically from iron and steel.

First, each pattern half is heated to 175-370 °C (350-700 °F) and coated with a lubricant to facilitate removal. Next, the heated pattern is clamped to a dump box, which contains a mixture of sand and a resin binder.

MOULD CREATION

MOULD ASSEMBLY

The two shell halves are joined and securely clamped to form the complete shell mould

MOULD ASSEMBLY

The mould is securely clamped together while the molten is poured from a ladle into the gating system and fills the mould cavity

Pouring

COOLING After the mould has been filled the molten metal is allowed to solidify

into the shape of the final casting

CASTING REMOVAL After the molten metal has been cooled , the mold can be broken and

casting can be removed

Trimming and cleaning process can be used to remove any excess metal from the feed system and sand from the mould

http://youtube.com/watch?v=44R2IbzTvt4

VIDEO LINK

ADVANTAGES & DISADVANTAGES

One of the greatest advantages of this process is that it can be completely automated for mass production

The high productivity, low labour costs, good surface finishes, and precision of the process can more than pay for itself if it reduces machining costs

One disadvantage is that the gating system must be part of the pattern because the entire mould is formed from the pattern, which can be expensive.

Another is the resin for the sand is expensive, however not much is required because only a shell is being formed

Thank you SAMSUL HAK