Prototyping for Production FAQ

An effective investment casting prototype should be more than a mere replica. It should be robust enough for strength testing, accurately represent the final part's geometry, and serve as validation of 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 cater to specific project needs, and our team of engineering experts has extensive experience producing prototypes across various industries and applications.

Prototyping options for productive testing

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

Short-run, hard tooled prototype

If a prototyping process is needed 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 compared to processes using SLAs or PMMAs. If a project demands 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 to replicate the mechanical properties of an investment cast component, 3D printed wax patterns offer efficiency and a quick turnaround. These patterns are produced in-house within hours and are immediately transformed into functional metal components. Recent technological progress has simplified the validation of surface finishes on these prototypes. The primary constraint of this process is component size, as printers can only handle parts roughly 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, besides 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. Similar to 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 serves as a good indicator 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 most suitable for low-volume aluminum alloy parts. Machining stainless steels and carbon steels takes longer, potentially increasing costs.

DMLS (Direct Metal Laser Sintering)

This process is appropriate for prototypes with intricate geometries and precise, untoolable features. However, it's 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 might not withstand real-world testing.

Which prototyping process is most effective for mass production?

During a successful product launch, a combination of different processes might be utilized. The optimal prototyping process for any given testing stage depends on the project's scope and proximity to product launch.

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

Maximizing 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 mold flow and solidification, castibility, or alloy compatibility.