sand casting

Download Sand Casting

Post on 28-Oct-2014




2 download

Embed Size (px)




Sunil Sutar MTech (Design Engineering)Presented to-

M P Gururajan Assistant Professor Applied Mechanics Department

Different ComponentsDifferent AspectsSmall Simple

23 feet, 6 tonnes , 99.72% iron, No rust since 5th century AD Big Complex

Iron pillar

Courtesy: Google images

CastingCasting = Pattern making + Mold making + Pouring Molten Metal + Cooling + Removal + Inspection Types of Casting : Expendable Mold, Multiple Use Mold Sand Casting : Expendable Mold casting process uses sand as molding material

Casting Terminology

Parting line

Courtesy: efunda

Pattern MakingWhat is pattern? Approximate duplicate of product Pattern material: Wood, Metals, Urethanes etc. Types of Patterns: One Piece or solid pattern, Split Pattern, Match-plate pattern, Drag & Cope Pattern Allowances: Shrinkage, Machining, Draft, Distortion

Pattern Making

One piece or Solid Pattern

Split Pattern

Match Plate Pattern

Cope & Drag Pattern

Mold Making Consists : Sand Preparation and Mold Making Sand Properties : Refractoriness, Cohesiveness, Permeability, Collapsibility How to get these properties? Mold Making Methods: Hand Ramming, Sand Slinger, Jolting, Squeezing, Combination

PouringPouring System:Pouring cup/Basin: Rectangular Shape-No vortex-No suction of Gases

Sprue: Short-Less KE Less turbulenceTapered shapeSprue Well : Dissipate KEPrevent splashing less turbulence

PouringRiser Need : Directional Solidification Feeding molten metal to compensate for solidification shrinkage

Criteria: Riser should solidify after the casting.Types:

Image Courtesy: wiki

Cooling/SolidificationCooling Curve for a Pure Metal:Pouring Temp.: Temp of first liquid entering Mold cavity Alloy-Distinct M.P.-freezing range High Cooling Rate-fine structures-good mechanical properties Chvorinos rule : ts=B(V/A)n

Start of Solidification

End of Solidification

B=Mold constant n=1.5 to 2

Effect of Cooling rate: Process Sand Casting Permanent Mold Die Cast Cast Structure:

SolidificationYield Strength(MPa) 55 62 110 Tensile strength(MPa) 131 158 227 Elongation(%) 8 10 9

Image Courtesy: wiki

Removal of Casting: Shake out-vibrating machine Shot blasting-Removal of internal surface sand

Trimming: Excess material-manual cutting, sawingTrimming Press

Inspection: Nobody is perfectSand Casting tooDefects

Casting Defects:

Image Courtesy: IITM, Manufacturing Processes, Lecture notes

Different Sand Casting Processes:Green Sand Casting: 88% silica sand, 9% clay,3% water

CO2 Molding: Sodium Silicate(3-6%)-CO2 flow- Strength Gain

Shell Molding: Silica Sand + Thermo setting phenolic resin+ heat sensitive liquid catalystshot on preheated metal pattern-shell formation

Summary:Includes :Casting=PMPCRI Sand Casting -versatile process -produce almost all size & shape of components -poor surface finish and dimensional accuracy. Sand Casting Methods : Green Sand, CO2 sand , Shell

Acknowledgements:1. Materials and Processes in Manufacturing, J T Black and Ronald A Cohser, 10 th edition. 2. Assistant Professor M P Gururajan

Thank you