1. 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

2. 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

3. 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

4. Casting Terminology
Parting line
Courtesy: efunda

5. 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

6. One piece or Solid Pattern
Pattern Making
One piece or Solid Pattern
Split Pattern
Match Plate Pattern
Cope & Drag Pattern

7. 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

8. 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

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

10. 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

11. 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

12. 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…

13. Image Courtesy: IITM, Manufacturing Processes, Lecture notes
Casting Defects:
Image Courtesy: IITM, Manufacturing Processes, Lecture notes

14. 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

15. 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

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

17. Thank you…