Introduction To Casting Processes by Stead Fast Engineers Pvt Ltd – part 1

one of the leading Induction heating system manufactures

History of Casting

Advantages• Complex forms, low cost• Certain shapes cannot be

machined• One piece parts vs. multiple

piece parts• Design changes are easily

incorporated• High volume, low skilled

labor• Large, heavy parts can be

made easily

Disadvantages• Problems with internal

porosity• Dimensional variations

due to shrinkage• Trapped impurities,

solids and gasses• High-tolerance, smooth

surfaces not possible• More costly than

stamping or extruding in some cases

Expendable Molds

• Green Sand• Dry Sand• Shell• Investment• Plaster

Expendable Molds

• Pattern must be produced

• New mold for every cycle

Permanent Molds• Die• Centrifugal• Pressure• Injection

Permanent Molds

• Made of durable material

• Multiple use• Built-in Alignment

Cupola Furnaces

Five Zones• Stack• Charging Zone• Melting Zone• Tuyers (Air Intake)• Crucible or Hearth

Induction Furnaces

• Magnetic field• Rapid melting rate• Low pollution

Foundries• Pattern and Mold

Making– Computer Aided

Design– Manufacturing– Rapid Prototyping

• The Casting Process– Metal Melting– Metal Compositions– Impurities– Pouring into molds

Foundries

Foundry Automation

• Pouring into Molds• Cleaning• Heat Treatment• Inspection• Automated Guided

Vehicles– Automatic Storage– Moving Cores and

patterns– Etc.

Reasons For Automation

• Increased Manufacturing Efficiency

• Reducing Costs• Reliability in Harsh

Environments • Release of Skilled Man

Power• Maximize Space• Improved Quality

Why Fluid Flow?

• When Heated Metal Becomes Liquid

• Important in Cast Design- Sprue - Well - Runner- Gate

Fluidity of Metals

• Viscosity • Surface Tension• Inclusions• Mold Design• Degree of Super Heat• Mold Material

- Thermal Conductivity

- Surface Roughness• Heat Transfer

Tests for Fluidity

• There are several different fluidity tests

• All use the same principle

• Useful in simulating how metal will react

• See how far the metal will travel before solidification

Heat Transfer• Heat transfer is

important in many aspects of casting- Pouring- Solidification- Cooling rate

- Rate is a function of Volume and surface area