Published - 18th Jun 2025
Investment casting is a precision manufacturing process that produces complex and high-integrity metal components. It is widely used in demanding sectors such as aerospace, defence, energy and medical, where performance and reliability are critical.
In this guide, we explore the investment casting process in depth and explain why it remains the preferred choice for engineers and buyers looking for high-quality parts. We also showcase how Investacast (part of Expromet Technologies Group) delivers a full manufacturing partnership – providing customers with expert advice, a choice of UK and global manufacturing options, and end-to-end delivery.
Investment casting, also known as lost wax casting, is a metal forming process that uses a sacrificial wax pattern to create precise and complex components. The wax model is coated in ceramic, which hardens to form a mould. Once the wax is melted and drained, molten metal is poured into the cavity to form the final casting.
This process enables intricate designs, fine surface finishes and tight tolerances that would be difficult or expensive to achieve with other methods. It’s ideal for medium-sized production runs and for components where geometry and performance are key.
Investment casting typically follows these stages:
This method supports a wide range of metals and alloys, and achieves superior accuracy with minimal material waste. The result is a near-net shape component that often requires little or no machining, saving time and cost in the production cycle.
Investment casting is compatible with numerous ferrous and non-ferrous metals, including:
Each material offers different mechanical properties and levels of corrosion resistance, allowing engineers to tailor their material choice to the demands of the application. For example, nickel-base alloys are well suited to high-temperature environments such as turbines or exhaust systems. At Investacast, our ability to air cast nickel-base superalloys demonstrates our capability to deliver advanced components for extreme conditions.
Read more about nickel-base superalloy castings
Designing for investment casting requires close attention to geometry and process limits. When designing a component, engineers should consider:
Early collaboration with Investacast enables customers to optimise their designs, reducing cost and improving performance.
Read more about design for manufacture in investment casting
Thanks to its precision and versatility, investment casting is used across a wide range of industries. Applications include:
Whether you’re designing for extreme pressure, corrosive environments or weight-sensitive assemblies, investment casting can offer a solution.
Explore Investacast’s UK manufacturing capabilities
Engineers and buyers favour investment casting for the following reasons:
These advantages make it ideal for both performance-critical components, and projects where cost-efficiency matters.
Like all manufacturing methods, investment casting has limitations. It may not be the best choice for:
Investacast offers a full suite of manufacturing options and can guide customers to alternative processes like pressure die casting or forging if investment casting is not the most suitable method.
Explore pressure die casting services
Explore forging and pressing options
Choosing the right process depends on the application. Here’s how investment casting compares:
Method | Detail level | Material efficiency | Suitability |
Investment casting | High | High | Complex, precise parts |
Sand casting | Low-Medium | Moderate | Larger, less complex |
Die casting | High | High | High-volume production |
| CNC machining | Very high | Low (high waste) | High precision, simple |
This overview helps engineers and procurement teams match the process to the part specification.
Read a more detailed comparison of casting vs other manufacturing methods
Understanding the tolerances and surface finish achievable is essential when designing components and planning downstream operations. Investment casting delivers excellent as-cast tolerances and finish.
Typical tolerances depend on the complexity, size and geometry of the component:
These tolerances meet or exceed ISO 8062-3 standards for investment castings. Critical features or mating surfaces can be finish-machined to tighter tolerances as required.
Check investment casting tolerances under ISO 8062 here
Surface finish is another advantage of investment casting. As-cast surfaces typically achieve a roughness average (Ra) of 3.2–6.3 µm, which is significantly smoother than sand casting or forging. For applications where aesthetics or fluid flow are important, post-cast treatments such as polishing, blasting or machining can further improve surface quality.
At Investacast, we work closely with customers to ensure that all dimensional and surface finish requirements are clearly defined and achieved. Our capabilities include in-house machining, finishing and inspection to deliver fully compliant components as part of our end-to-end service.
Understanding what to expect from a project helps engineers and buyers make informed decisions. At Investacast, we simplify and de-risk the process:
Customers benefit from a transparent and collaborative partnership throughout.
Although investment casting is a highly accurate and repeatable process, like all manufacturing techniques, it is not immune to defects. Understanding these potential issues, and how they are addressed, is essential to ensure the reliability and quality of the final component.
Common investment casting defects include:
Investacast implements rigorous quality control procedures to eliminate or reduce these risks:
Investacast operates under ISO 9001:2015-certified quality management systems and supports industries where component integrity is critical, such as aerospace, defence and medical. Our quality commitment ensures your components perform as designed, every time.
Investment casting costs vary depending on:
At Investacast, we help buyers assess the total cost of manufacturing their metal component using investment casting. By factoring in set-up and prototyping costs as well as the impacts of reduced waste, lower machining time and longer tool life, we can give our customers clear guidance on the relative merits of different manufacturing choices and UK and overseas sourcing.
A reliable supplier can make or break a project. When choosing a supplier for investment castings, look for:
With over 70 years of experience, Investacast meets or exceeds all these requirements. Investacast is trusted by OEMs, Tier 1s and Primes across the globe as an expert metal manufacturing partner.
Buyers sourcing investment castings should have clear parameters when approaching an investment casting company, so that they can:
However, Investacast engineers are always happy to help buyers work out the optimal solution for each component to be manufactured. Investacast supports procurement teams right through the process, from concept through to production and aftersales. Our engineering-led approach ensures that buyers aren’t just ordering a component – they’re gaining a technical partner.
From helping refine designs for better manufacturability to selecting the most appropriate material and production route, we work collaboratively to deliver quality parts efficiently and on time. This customer-focussed process, backed by decades of casting experience, the support of our sister companies in Expromet Technologies Group, and an extensive global supply network, gives buyers complete confidence in achieving the right outcome.
Investment casting is resource-efficient in many respects, especially when compared to subtractive processes like CNC machining. It generates less scrap, uses near-net shape manufacturing to minimise excess material, and offers design flexibility that can reduce the need for assembly.
However, it’s important to acknowledge that the process is also energy intensive – particularly in the shell building, dewaxing and metal melting stages. The investment casting process can have other environmental impacts, such as:
At Investacast, we are committed to mitigating these impacts and improving sustainability across our operations. Measures include:
Furthermore, our ability to offer UK-based manufacturing supports customers looking to shorten their supply chains and reduce the carbon footprint associated with global shipping. By continually reviewing our processes and embracing cleaner technologies, we aim to deliver both performance and environmental responsibility.
As manufacturing evolves, investment casting is being enhanced by technological, material and market-driven shifts. These developments are opening up new possibilities in design, speed, cost efficiency and environmental performance.
Investacast embraces innovation to remain at the forefront of advanced metal manufacturing and to meet the evolving needs of its customers.
Investment casting continues to evolve with innovations that enhance quality, efficiency and competitiveness. At Investacast, we invest in technology that delivers measurable benefits for our customers:
Learn about Expromet Technologies Group
Investment casting remains one of the most precise, efficient and flexible metal manufacturing processes available today. For engineers, it offers the freedom to design complex, high-integrity components in a range of materials. For buyers, it provides a dependable route to quality, consistency and long-term cost efficiency.
At Investacast, we combine over 70 years of casting expertise with the latest technologies and a global supply chain to deliver a seamless experience – from concept and prototyping through to full production and on-time delivery. Whether you need UK-based manufacturing, support with design optimisation, or help choosing the right process for your part, we’re here to guide you every step of the way.
If you’re looking for a casting partner who understands both the technical and commercial demands of your sector, we’d love to hear from you.
Contact Investacast to discuss your project
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For buyers and engineers new to the investment casting process, it’s natural to have questions about capabilities, timelines and suitability. This section addresses the most common queries we receive from prospective customers.
What size parts can be investment cast?
From a few grams up to 30kg in the UK and up to 500lb (c.225kg) outsourced, depending on alloy and geometry.
What industries use investment castings?
Aerospace, energy, medical, semiconductor production, automotive, industrial automation and more.
Can I get prototype parts made?
Yes – rapid prototyping options are available, including 3D printed patterns.
What types of materials can be investment cast?
Common materials include stainless steel, aluminium, carbon steel, bronze, and nickel-base superalloys.
How accurate is investment casting?
Tolerances of ±0.1 mm to ±0.5 mm are achievable depending on part size and geometry.
Is investment casting suitable for high-performance or safety-critical components?
Yes – it is widely used in aerospace, medical and defence where precision and reliability are essential.
How does investment casting compare to CNC machining or die casting?
Investment casting is ideal for complex, lower-volume parts with fine detail. CNC machining offers ultimate precision but higher material waste. Die casting is faster for high-volume runs but more limited in material choice.
Can Investacast help optimise my design for casting?
Absolutely. Our engineers provide design for manufacture (DfM) support to improve castability, reduce cost and ensure the best results.
Does Investacast offer UK and overseas manufacturing options?
Yes – we offer UK investment casting from our Devon base and global sourcing via trusted foundry partners.
If you have a project, talk to our experienced sales team
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