Cast Iron, Cast Steel and Powder Metallurgy

Cast Iron, Cast Steel and Powder MetallurgyProperties of Materials BTM2413Casting ProcessCasting a shape achieved by allowing liquid to solidify in a moldCasting processSand Casting

Casting ProcessDie Casting

Casting ProcessPermanent Mold Casting

Casting ProcessShell molding Casting

Casting ProcessCentrifugal casting

Casting MoldSand moldMold made by sand

Casting MoldMetal moldMold made by metal Graphite mold

8Melting Techniquesa)Cupola

9Melting TechniquesCast iron melting process in cupola

Burning the coke

Air is supply to the coke bed

Solid metal charged into the furnace through charging door

The metal is alternated with layers of coke and drip down through the coke bed

When the metal level is sufficiently high, tap hole is opened to collect the molten metal10Melting Techniquesb) Electric Arc

11Melting Techniquesc) Induction

12Melting Techniquesd) open-hearth

13Melting Techniquese) reverberatory

14Factors Of Casting ProcessFactors to be Considered in evaluating/selecting a casting process:

Tolerance It is needed to compensate with shrinkage rate (1% -5%)Depend on nature of the metal being cast (melting point) and nature of process.Investment castings have the lowest tolerances that apply to ferrous and non-ferrousSand casting has the largest tolerances

15Factors Of Casting Process2) Surface Finish

ProcessSurface Roughness (m)Die casting0.5 2.5Investment Casting1.25 2.5Shell Molding6.25 17Sand Casting6.25 - 2516Factors Of Casting Process3) Size LimitationsLarge die casting may weight up to 18 kgInvestment casting seldom exceed 13kg, seldom longer than 450 mmNo size limit for sand castingMost cast-iron pipes are centrifugal casting

4) MaterialsPermanent mold and centrifugal casting suitable for ferrous metalShell molding, investment casting, sand casting, centrifugal casting, and permanent mold can be applied to all common metal

17Factors Of Casting Process3) Casting costDepend on hardware used; sand casting : hardware required is wooden pattern, other process mostly metal mold and quite expensiveSand casting required long time to processDie casting is the fastest process

4) Availability- Time to build the hardware-sand casting is the simplest process

18Powder MetallurgyPowder Metallurgical Process

Blending of powdersMetal powders in the size range from 10 to 80 m, are blended to achieve the desired powder mix and to add compaction lubricants2) Filling of compaction dieThe powder is fed into the open die3) Compaction The upper and lower compaction tools then simultaneously compact the powder with pressure. Compaction is performed in hardened steel tooling machine

19Powder MetallurgyPowder Metallurgical Process

4) Part ejectionUpper compaction punch retracts and the lower punch rises to eject the compacted shape5) Sintering

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