Investment Casting

Introduction

Investment casting (also known as lost wax casting) is a highly precise manufacturing process that enables the production of complex metal parts with geometries that are difficult or impossible to achieve using other methods. Leading industries, from aerospace to medical devices, rely on this method when precision and surface quality are critical.

What is Investment Casting?

Investment casting is an ancient manufacturing technique that dates back thousands of years. Today, it is widely used in modern industry for producing highly detailed and complex components.

The process involves creating a wax model of the final part, coating it with ceramic layers, removing the wax and pouring molten metal into the resulting mold.

The final product is a highly accurate metal part that replicates the original wax model. Unlike machining, where material is removed from a solid block, investment casting starts with liquid metal, allowing for complex internal and external geometries.

Key Advantages of Investment Casting

Investment casting is suitable for manufacturing parts with:

• Complex geometries
• Hollow components
• Tight tolerances (typically ±0.1–0.3 mm)
• Smooth surface finish without additional machining
• A wide range of sizes, from small grams to large components

How Does the Process Work?

1. Wax Pattern Creation
Wax is injected into a precision mold (die) to create exact replicas of the desired part.

2. Ceramic Shell Coating
The wax model is repeatedly dipped in ceramic slurry and coated with refractory sand. This process is repeated multiple times to build a strong shell.

3. Dewaxing
The ceramic shell is heated in a furnace, causing the wax to melt and drain away, leaving a hollow mold.

4. Metal Casting
Molten metal is poured into the heated ceramic mold. Casting at high temperatures improves metal flow and reduces internal stress.

5. Finishing and Inspection
After cooling, the ceramic shell is broken, and the part is cleaned, finished and inspected.

Applications of Investment Casting

Investment casting is widely used in industries that require high precision and reliability:

Aerospace
Turbine blades, structural components and engine parts made from nickel-based alloys.

Defense
Weapon components, adapters and precision systems requiring consistency and durability.

Medical
Surgical tools, orthopedic implants and imaging equipment components made from stainless steel or titanium.

Materials Used in Investment Casting

A wide range of alloys can be used:

• Stainless steel – corrosion resistant
• Nickel alloys – high temperature resistance
• Titanium – high strength-to-weight ratio
• Steel alloys – strong and durable
• Cobalt-chrome – commonly used in medical applications

Investment Casting vs Other Methods

Investment casting is ideal when:

• Complex geometries are required
• High surface quality is needed (Ra 1.6–3.2)
• Tight tolerances are critical
• Special alloys are used

Other methods:

• Vacuum casting – mainly for prototypes
• Die casting – suitable for high-volume simple parts

Quality Control in Investment Casting

Quality control is essential, especially in aerospace and medical industries.

It includes:

• Dimensional inspection (CMM)
• Non-destructive testing (X-ray, ultrasound, dye penetrant)
• Mechanical testing (strength, fatigue)
• Metallographic analysis
• Full traceability and documentation

Standards such as ISO 9001, AS9100 and ISO 13485 are commonly required.

About Our Services

We specialize in supplying high-quality investment cast components for advanced industries including aerospace, defense, medical and semiconductors.

We work with certified manufacturers to ensure precision, consistency and reliability in every part.

FAQ

What is the difference between investment casting and vacuum casting?
Investment casting is used for metal parts, while vacuum casting is typically used for polymers and prototyping.

How long does the process take?
Tooling usually takes 4–8 weeks, followed by 2–4 weeks for initial production.

What tolerances can be achieved?
Typically ±0.1 to ±0.3 mm, depending on part complexity.

What is the minimum production quantity?
Usually suitable for batches from dozens to thousands of parts.