Casting is a manufacturing process in which molten metal is poured into a mould cavity, allowed to solidify, and then removed to produce a shaped metal component.

**What is process of casting?-Everything you need to know**

Casting Process in Manufacturing

Here’s a complete, detailed explanation of the casting process in manufacturing, definition, types, steps, materials, advantages, disadvantages, and applications.

1. Definition of Casting

Casting is a manufacturing process in which molten metal is poured into a hollow mold cavity, allowed to solidify, and then removed as a solid metal part of the desired shape.

Casting = shaping metal by pouring it into a mold and letting it solidify.

2. Principle of Casting

Molten metal flows into the mold cavity by gravity, pressure, or vacuum
Metal cools and solidifies, taking the shape of the mold
Mold is removed (broken or opened), leaving the casting

Key Concept: Molten metal → Mold → Solidified part

3. Types of Casting

A. Based on Mold Material

Type	Description	Examples
Sand Casting	Mold made of sand (green sand or chemically bonded)	Engine blocks, pump housings
Die Casting	Permanent metal die; molten metal injected under pressure	Gear housings, electrical components
Investment Casting	Wax pattern coated with ceramic shell	Turbine blades, aerospace parts
Centrifugal Casting	Mold rotated to force metal outward	Pipes, rings, cylinder liners
Shell Molding	Thin shell of sand + resin	Small precision parts

B. Based on Metal Flow

Gravity Casting: Molten metal flows under gravity
Pressure Casting: High-pressure injection into mold (die casting)
Vacuum Casting: Vacuum assists filling, reduces porosity

4. Process Steps of Casting

The casting process generally includes the following steps:

Step 1: Pattern Making

Create a replica of the part (slightly oversized to allow for shrinkage)
Materials: Wood, metal, plastic, wax

Step 2: Core Making (if required)

Used to form internal cavities in the casting
Materials: Sand, salt, ceramic

Step 3: Mold Making

Sand Casting: Pack sand around pattern
Die Casting: Steel die is machined
Investment Casting: Coat wax pattern with ceramic

Step 4: Melting the Metal

Heat metal above its melting point in a furnace
Maintain proper alloy composition

Step 5: Pouring / Injection

Molten metal poured into mold or injected under pressure
Ensure smooth flow to avoid turbulence

Step 6: Cooling / Solidification

Metal cools in mold
Cooling rate affects microstructure, strength, and shrinkage

Step 7: Mold Removal

Sand Casting: Break the sand mold
Die Casting: Open the die
Investment Casting: Remove ceramic shell

Step 8: Fettling and Cleaning

Remove gates, risers, flash, and excess metal
Grinding, sanding, or shot blasting

Step 9: Heat Treatment (Optional)

Improve strength, hardness, or ductility

Step 10: Inspection and Testing

Dimensional checks, visual inspection, X-ray, dye penetrant
Detect defects like porosity, cracks, cold shut

5. Materials Used in Casting

Ferrous metals: Iron, steel, stainless steel, alloy steel
Non-ferrous metals: Aluminium, copper alloys, zinc, magnesium
Special alloys: Titanium, nickel superalloys (for aerospace)

6. Advantages of Casting

Can produce complex shapes
Can cast large and heavy components
Versatile: Any metal or alloy
Minimal machining required for near-net shapes
Cost-effective for medium to large production

7. Disadvantages of Casting

Lower dimensional accuracy (except die and investment casting)
Poor surface finish (sand casting)
Defects like porosity, shrinkage, and misruns
Slow production cycle for some casting types
Not suitable for very thin walls (<2 mm in sand casting)

8. Common Defects in Casting

Porosity / Blow holes: Gas trapped in metal
Shrinkage cavities: Metal contracts during cooling
Misruns: Metal does not fill the mold
Cold shuts: Metal solidifies before merging
Sand inclusions: Particles trapped in metal

9. Applications of Casting

Engine blocks, cylinder heads, pump housings
Gearboxes, valve bodies
Aerospace turbine blades
Electrical housings
Industrial machinery parts
Jewelry and decorative items

10. Summary

Casting is a metal shaping process where molten metal is poured into a mold, solidified, and removed to produce components of desired shape. It is versatile, suitable for complex and large parts, but may have defects and lower accuracy.

Conclusion

Casting is the process of producing metal parts by pouring molten metal into a mold, allowing it to solidify, and removing the mold to obtain the desired shape.