Investment casting uses wax to make the pattern, ceramic slurry for the mould shell, and metals such as steel, stainless steel, aluminum, and superalloys for the final casting.

Materials Used in Investment Casting

In investment casting (lost-wax casting), materials are not limited to just the final metal. Several different materials are used at each stage of the process—from pattern making to shell formation and final casting. Below is a clear, detailed, exam-ready explanation.

1. Pattern Materials (Wax & Alternatives)

(a) Wax (Most Common)

Wax is used to make the disposable pattern.

Types of wax used:

Paraffin wax
Microcrystalline wax
Synthetic wax
Filled wax (with resins or fillers)

Properties required:

Low melting point
Good surface finish
Dimensional stability
Easy removal without residue

(b) Plastic (Alternative)

Used when:

Stronger pattern needed
Automation required

Materials:
Polystyrene, PMMA

2. Ceramic Shell Materials (Mould Material)

The ceramic shell forms the actual mould.

(a) Refractory Materials

Provide heat resistance.

Common refractories:

Silica (SiO₂)
Zircon (ZrSiO₄)
Alumina (Al₂O₃)
Mullite

(b) Binder Materials

Hold ceramic particles together.

Binders used:

Colloidal silica (most common)
Ethyl silicate

(c) Stucco (Coarse Particles)

Sprinkled over wet slurry layers for strength.

Stucco materials:

Silica sand
Zircon sand
Alumina sand

3. Core Materials (If Internal Cavities Are Needed)

Ceramic cores
Soluble cores (salt-based)
Silica-based cores

Used to create:

Internal passages
Hollow sections

4. Metals and Alloys Used for Casting

(a) Ferrous Alloys

Carbon steel
Alloy steel
Stainless steel

Used in:

Valves
Automotive and industrial components

(b) Non-Ferrous Alloys

Aluminium Alloys

Lightweight
Good corrosion resistance

Applications: automotive, aerospace

Copper Alloys

Brass
Bronze

Applications: marine, electrical

Nickel-Based Superalloys

Inconel
Hastelloy

Applications: turbine blades, aerospace

Titanium Alloys

High strength-to-weight ratio
Excellent corrosion resistance

Applications: aerospace, medical implants

Cobalt Alloys

Wear and heat resistant

Applications: medical, cutting tools

5. Auxiliary Materials Used

(a) Release Agents

Silicone sprays
Soaps

Prevent wax sticking to dies.

(b) Coatings

Improve surface finish
Control metal-mould reaction

(c) Fluxes & Degassing Agents

Improve metal quality
Reduce oxidation and porosity

6. Summary Table

Stage	Materials Used
Pattern	Wax, plastic
Shell	Silica, zircon, alumina
Binder	Colloidal silica, ethyl silicate
Casting metal	Steel, Al, Ti, superalloys
Cores	Ceramic, soluble salts

7. Summary

Investment casting uses wax or plastic patterns, ceramic shell materials such as silica, zircon, and alumina, binders like colloidal silica, and a wide range of ferrous and non-ferrous metals including steels, aluminium, titanium, and superalloys.