What Is Open Cast Moulding And When Should It Be Used?
Open cast moulding is a versatile and cost-effective manufacturing technique used across a range of industries to produce precision-moulded components.
At Polytech Mouldings, we specialise in delivering high-quality, tailored moulding solutions, including open cast moulding, at our UK-based manufacturing facility.
Whether you're in the aerospace, automotive, renewables or marine sector, understanding the benefits and applications of open cast moulding can help you make informed decisions for your product development.
So, what exactly is open cast moulding? How does it compare to other moulding methods, and which situations is it most useful?
What Is Open Cast Moulding?
Open cast moulding, also known as ‘open mould casting’, is a low-pressure process used to create rubber or polyurethane components. Unlike injection moulding, which forces material into closed moulds under high pressure, open cast moulding involves pouring liquid material into an open mould. This allows it to cure at atmospheric pressure.
This method is particularly suited to thermosetting materials, such as polyurethane elastomers, which cure chemically without needing extreme temperatures or pressures. Once the material sets, the mould is opened, and the finished component is removed.
Key Characteristics of Open Cast Moulding:
- Tooling is simple and cost-effective, making it ideal for small to medium production runs.
- Materials cure naturally without the need for high-pressure injections.
- Versatile shapes and sizes can be achieved, including complex geometries and large components.
- It involves less waste and energy compared to high-pressure methods.
When Should You Use Open Cast Moulding?
Open cast moulding is ideal when your project needs:
- Customisation and flexibility
- Lower upfront tooling costs
- Shorter lead times
- High performance in demanding environments
Let’s take a closer look at some of the most common applications and use cases.
1. Prototyping and Low to Medium Volume Production
The affordability of tooling makes open cast moulding a go-to solution for prototyping or limited production runs. Unlike injection moulding, which requires expensive, complex tooling, open cast moulds can be created quickly and affordably, so modifications can easily be made to a design.
2. Complex or Large Components
Because there’s no need for high-pressure injection systems, open cast moulding can accommodate larger parts and intricate designs more easily. This makes it well-suited for bespoke components in industries such as construction and marine where oversized or unusually shaped parts are common.
3. Polyurethane and Elastomer Components
Open cast moulding works especially well with polyurethane elastomers, which offer excellent abrasion resistance, flexibility, and chemical resistance. These materials are often used in high-wear applications, such as agricultural seals, gaskets, rollers, and vibration dampeners.
4. Projects That Require Fast Turnaround
Why Choose Polytech Mouldings?
At Polytech Mouldings, we don’t just offer open cast moulding: we build bespoke solutions from the ground up. Our team works closely with customers from the design phase through to material selection, tooling design, and final delivery.
In-House Tooling Capabilities
We offer full in-house tooling design and manufacture, ensuring faster lead times, tighter quality control, and more responsive product development. Because we manage the entire process internally, we’re able to adapt quickly to changes, resolve issues proactively, and deliver components tailored to your exact specifications.
Industry Expertise Across Critical Sectors
With clients in aerospace, rail, automotive, and more, we understand the importance of reliability, precision and compliance. Our ISO 9001:2015 certification guarantees strict quality control at every stage.
Whether your components are destined for high-vibration environments or exposed to harsh chemicals, we have the experience to recommend the right materials and processes.
Committed to Greener Practices
As part of our commitment to sustainable manufacturing, we’ve built environmental best practices into our operations. From optimising energy use to reusing packaging materials and recycling non-reusable waste, we ensure our solutions are not only effective but also responsible.
Is Open Cast Moulding Right for You?
Open cast moulding is not the right fit for every project, but when flexibility, speed, and customisation are essential, it’s often the best choice. At Polytech Mouldings, we combine technical knowledge with a customer-first approach, making us a long-term partner for your most critical moulded components.
Whether you need a one-off prototype or a steady supply of high-performance polyurethane parts, our open cast moulding services provide the agility and reliability you need to keep moving forward.
Our Services Also Include Tool Making
We have many years of experience in this area, with our bespoke moulds facilitating the production of new and innovative solutions.
The design and manufacture of moulds can be complex, and it’s vital for parts to be accurate early on. At the same time small changes in the design process can provide added value in later production, ensuring moulded parts are as effective and successful as possible.
Ready to explore your options? Contact our team to discuss your next project or request a quote. Let’s create something built to last.
