SAND CASTING Sunil Sutar MTech (Design Engineering) M P Gururajan HOME ASSIGNMENT PART II SAND CASTING Prepared By- Sunil Sutar MTech (Design Engineering) Presented to- M P Gururajan Assistant Professor Applied Mechanics Department

Different Components…Different Aspects Simple Small 23 feet, 6 tonnes , 99.72% iron, No rust since 5th century AD Big Complex Iron pillar Courtesy: Google images

Casting Casting = 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 Making What 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

One piece or Solid Pattern 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

Pouring Pouring System: Pouring cup/Basin: Rectangular Shape-No vortex-No suction of Gases Sprue: Short-Less KE –Less turbulence-Tapered shape Sprue Well : Dissipate KE-Prevent splashing –less turbulence

Pouring Riser Need : Directional Solidification Feeding molten metal to compensate for solidification shrinkage Criteria: Riser should solidify after the casting. Types: Image Courtesy: wiki

Cooling/Solidification Cooling Curve for a Pure Metal: Pouring Temp.: Temp of first liquid entering Mold cavity Start of Solidification End of Solidification Alloy-Distinct M.P.-freezing range High Cooling Rate-fine structures-good mechanical properties Chvorino’s rule : ts=B(V/A)n B=Mold constant n=1.5 to 2

Tensile strength(MPa) Solidification Effect of Cooling rate: Process Yield Strength(MPa) Tensile strength(MPa) Elongation(%) Sand Casting 55 131 8 Permanent Mold 62 158 10 Die Cast 110 227 9 Cast Structure: Image Courtesy: wiki

Removal of Casting: Shake out-vibrating machine Shot blasting-Removal of internal surface sand Trimming: Excess material-manual cutting, sawing-Trimming Press Inspection: Nobody is perfect…Sand Casting too…Defects…

Image Courtesy: IITM, Manufacturing Processes, Lecture notes 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 catalyst-shot 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: Materials and Processes in Manufacturing, J T Black and Ronald A Cohser, 10 th edition. Assistant Professor M P Gururajan http://mogadalai.wordpress.com/2006/01/14/some-thoughts-on-making-presentations/

Thank you…