Prototyping for mass production

An effective investment casting prototype should be more than a mere replica. It should be robust enough for strength testing, accurately represent the geometry of the final part, and validate the concept. A well-executed, functional prototype is the crucial first step in taking a project from the drawing board to full-scale production.

Signicast offers a range of prototyping technologies to meet specific project requirements, and our engineering specialists have extensive experience producing prototypes across various industries and applications.

Prototyping options for effective testing

To select the most suitable prototyping process, the physical properties and testing requirements of the end component must be determined. These requirements help narrow down the available options.

Short-run, hard-tooled prototype

When a prototyping process is required to produce numerous parts that precisely match the mechanical and physical properties, dimensions and tolerances of the final component, a short-run, hard-tooled prototype is the most effective choice. Although it involves an initial tooling cost, it produces prototypes at a lower per-piece price than processes using SLA or PMMA. If a project requires an exact prototype and rigorous yield strength testing, a hard-tool prototype is the optimal solution.

3D-printed wax pattern

For design validation, proof of concept, fill validation or replicating the mechanical properties of an investment cast component, 3D-printed wax patterns offer efficiency and rapid turnaround. These patterns are produced in-house within hours and immediately transformed into functional metal components. Recent technological advances have simplified the validation of surface finishes on these prototypes. The primary constraint of this process is component size, as printers can only handle parts approximately the size of a Rubik's cube or smaller.

SLA (stereolithography)

SLA is similar to 3D-printed patterns but is used when the part size exceeds the capacity of our 3D printer, typically around the size of a sheet of paper (6 to 8 inches high). Like 3D-printed wax patterns, SLA prototypes mimic the mechanical properties of an investment cast component and are valuable for fit and design validation prototyping. The main distinction, aside from size, is that pattern removal in SLA is more manual.

PMMA (polymethyl methacrylate)

PMMA patterns resemble SLA patterns and can accommodate parts larger than those suitable for SLA. Like 3D wax patterns and SLA, PMMA is useful for refining surface finishes, fit and design validation, and replicating the mechanical properties of an investment cast component. PMMA also provides a good indication of the strength and repeatability of complex geometries.

Machined from solid

Machining from solid bar stock is generally a very rapid process, ideal for producing dimensionally accurate parts for fit assessment and proof of concept. To ensure speed, this process is best suited to low-volume aluminium alloy parts. Machining stainless steels and carbon steels takes longer, potentially increasing costs.

DMLS (Direct Metal Laser Sintering)

This process is suitable for prototypes with intricate geometries and precise features that cannot be produced with tooling. However, it is important to note that DMLS may not always match the mechanical properties of a true investment casting. While excellent for proof of concept and demonstrations, it may not withstand real-world testing.

Which prototyping process is most effective for mass production?

During a successful product launch, a combination of different processes may be used. The optimal prototyping process for any testing stage depends on the project scope and its proximity to product launch.

As the project approaches mass production, transitioning to a short-term hard-tooled investment casting run is recommended. This enables comprehensive testing and validation of all requirements for the final component.

Maximising prototype value

A crucial, yet often overlooked, aspect of prototyping is involving the supplier early in the design phase. Designing the prototype for optimal manufacturability is ideal, and the most direct way to achieve this is by collaborating with design engineers experienced in investment casting. This proactive approach can prevent setbacks during prototyping, such as the need to redesign a part to ensure proper mould flow and solidification, castability or alloy compatibility.