Prototype plastic injection molds produce real injection molded parts for functional testing. They can also serve as bridge tooling to fill the manufacturing gap for production tooling. Prototypes differ from production molds in that they usually are not meant to be used in the long term.
Prototype molding is built quickly. It has the shape and functionality needed for testing form, fit and function, but may not have fine details (like color preference or surface finish).
Unlike the final injection mold, the prototype mold is made from less expensive materials, such as non-hardened steel, aluminum, or P20 (low-carbon mold steel). Because these are far less durable than a final injection mold, they are not suitable to use for your final product.
Why Use a Prototype?
A prototype offers a means to efficiently and cost-effectively evaluate a mold before committing to the final product. Unsure of how best to meet specifications or what your final product should look like? Then a prototype can provide the solution. It can help you determine what works and what needs to be changed.
Because a prototype uses lower-cost materials and a faster process, you won't feel pressured to settle for something that doesn't meet your needs.
Making prototype molds is as much an art as it is a science. Several methods can be utilized to develop prototype parts. These include hand tooling, Master Unit Die (MUD) molds, and aluminum tooling. Let's look at the advantages of each.
Prototype hand tooling is the most cost-effective means of injection molding a part. This option is often used when looking for a production-quality prototype that provides the functionality needed for real-world testing.
It's also beneficial for quickly refining complex, ergonomically driven forms, such as those commonly found in consumer goods.
With MUD molds, a standard injection molding frame utilizes many inserts to define the internal cavity's shape. MUD inserts can be made with either a CNC machine or an Electric Discharge Machine (EDM), depending on the material requirements of the inserts themselves.
For example, injection molding with a plastic that has a very high molding temperature could require inserts made from a heavy metal alloy. A CNC machine may not be able to make the required cuts. In those cases where a CNC machine is not sufficient, an EDM can is typically used to handle the job.
MUD molds lower total cost and turnaround time for prototype revisions. The inserts can be easily removed, redesigned, and re-inserted while leaving the more substantial part of the tool in the injection mold machine. For this reason, if there is a requirement for significant debugging and adjustment to the injection molded part, then the MUD inserts are a great option.
Although solid aluminum tooling is often a final deliverable for a project, it's also used for prototyping. Aluminum tools can be designed to allow changes during the development process. In general, aluminum tools are easier to machine than steel tooling, making iterative design changes less burdensome.
What Is Rapid Prototyping?
Rapid prototyping (RP) uses three-dimensional computer-aided design (CAD) data. Construction of the part is usually done through 3D printing or "additive layer manufacturing" technology.
In addition to creating prototypes, RP is also used to manufacture production-quality parts in relatively small numbers.
Rapid prototyping includes stereolithography, selective laser sintering, fused deposition modeling, and laminated object manufacturing. Each of these techniques builds parts, one by one, from 3D-CAD models, joining layers of material to create the finished prototype.
The Right Method for Your Project
The right prototyping method at the proper phase of development will not only save time and money but also enable more (or more effective) iterations. In other words, better prototypes result in better end products.
Let the prototyping experts at Prodigy Mold & Tool suggest which method is best suited for your project.