HOME ASSIGNMENT PART II SAND CASTING Sunil Sutar MTech (Design Engineering) M P Gururajan Assistant Professor Applied Mechanics Department Presented to- Prepared By-
HOME ASSIGNMENT PART II
SAND CASTING
Sunil SutarMTech (Design Engineering)
M P GururajanAssistant Professor
Applied Mechanics Department
Presented to-
Prepared By-
Different Components…Different Aspects
SmallSimple
Big Complex
Courtesy: Google images
23 feet,6 tonnes ,99.72% iron,No rust since 5th century AD
Iron pillar
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
Pattern Making
One piece or Solid Pattern
Cope & Drag PatternMatch Plate Pattern
Split 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
Need :Directional SolidificationFeeding molten metal to compensate for solidification shrinkage
Criteria: Riser should solidify after the casting.
Types:
Riser
Image Courtesy: wiki
Cooling/SolidificationCooling 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 constantn=1.5 to 2
Effect of Cooling rate:
ProcessYield
Strength(MPa)Tensile
strength(MPa)Elongation(%)
Sand Casting 55 131 8Permanent Mold 62 158 10
Die Cast 110 227 9
Cast Structure:
Image Courtesy: wiki
Solidification
Removal of Casting:Shake out-vibrating machineShot 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:
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
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
Summary:
1. Materials and Processes in Manufacturing, J T Black and Ronald A Cohser, 10 th edition.
2. Assistant Professor M P Gururajan http://mogadalai.wordpress.com/2006/01/14/some-
thoughts-on-making-presentations/
Acknowledgements:
Thank you…