Determining the optimal number of prototypes for testing and validation can help accelerate the new product development process.

Written by Craig Crossley, Applications Engineer at Fortify

What is it?

For the past several decades, 3D printing has become synonymous with rapid prototyping and increased its notoriety as a viable manufacturing alternative. Improvements to printing processes, sintering, finishing and materials have opened doors to new opportunities that were  previously thought to be impossible. For example, the ability to 3D print injection mold tools for short run prototyping and production projects. This relatively new application is beginning to gain momentum for product developers, tool makers and contract manufacturers due to several unique advantages.

Those familiar with conventional injection molding (IM) for production purposes are well aware of the inherent benefits associated. An aluminum tool can produce thousands of parts, and steel tools remains the most efficient mass production method available today. However, the process doesn’t always yield the best results, and tooling mistakes can become economically problematic very quickly. Prototype injection molding with 3D printed tools has become a viable bridge-to-production tool and may be worth considering. 

First, it’s important to understand the time and cost differences between the different prototype methods. Our engineering experts at Fortify present the following:

Prototype injection mold tooling with 3D printing is uniquely advantageous to designers and engineers because it is an inexpensive and fast way to make mistakes. Hard or aluminum tooling is costly and very difficult to alter once the mold has been delivered, making it a logistical and financial nightmare. The data below shows how significant the cost difference is when comparing multiple prototype methods. Not to mention, a dramatic decrease in the product development timeline.

How is it used?

Prototype injection molding is a bridge-to-production method that minimizes risks and improves product validation well before mass manufacturing. The use of injection molding to prototype is beneficial for several reasons; (1) functional testing with end-use materials, (2) engineering & customer feedback, and (3) eliminating unforeseen challenges in production. 

  • Functional Testing | Prototype IM tooling is a cost efficient way for engineers to shoot end-use materials for true product testing and evaluation. For example, 3D printed mold tools are reinforced with ceramic fiber and are strong enough to be injected with a variety of thermoplastics that include polycarbonate, nylon 66, ABS and POM, Ultem, GF Ultem, and more. Now, the engineering team can produce 20+ prototypes that are representative of the final product ready to be tested and processed.
  • Feedback | Product development relies on internal and external feedback to make improvements. Having access to a small batch of product parts with prototype IM tooling enables beta customers and remote engineering teams immediate access to the product. This is ideal to enhance customer relationships or international organizations with multiple facilities. No delays or hold ups due to part scarcity. 
  • Unforeseen Challenges | Let’s face it, no one designs or prototypes the perfect part right off the bat. What’s more problematic to your new product development (NPD) lifecycle—wasted time or wasted money? The real answer is both. Therefore, adopting a prototype injection molding process will provide real answers to production problems that typically occur late in the game. Thus eliminating costly redesigns or worse, production mishaps.

When is the break-even point?

Prototype injection mold tools can be created with a variety of different technologies. As previously presented, it’s possible to use hard tooling, aluminum, or 3D printing depending on resources and availability. To put it into perspective, a normal mold order for a complex part that requires threads, texturing or undercuts could take approximately 5-8 weeks with an aluminum tool. That’s assuming that there are no alterations or changes within that time to further delay the process. However, Fortify offers a unique path towards a much faster and flexible solution. The gantt chart below shows a traditional 3 phase injection molding process. Presuming that the product development (Phase one) takes approximately three weeks, we can determine the next steps in the process comparing aluminum vs. Fortify molds.

Notice that the first shots with Fortify IM tools are delivered early in Phase 2 while aluminum tooling takes much longer, resulting in parts being shipped at the beginning of Phase 3 (~two weeks later). Assuming you require a single iteration, Fortify can produce parts immediately and have them available in as little as three days. The design finishes on Monday, printing begins overnight then cleaning and curing on Tuesday. On Wednesday, the molds/inserts are coated and parts are ready in a few hours. Second iteration? Third iteration? No problem, we repeat the process with an identical timeframe. 

Why is it so valuable?

The bottom line is the bottom line. Cost and time savings have been referenced several times throughout this guide, and it’s important to address it directly. 3D printed IM tools are perfect for the low volume production of prototypes or end-use parts. For any application, it’s important to determine what exactly is low volume and how it pertains to your particular product. This is not easy, so we recommend speaking with an expert to determine what makes the most sense for your application and process. 

Using a 6 x 4 x 2 model, we can establish a cost analysis for prototype injection mold tooling that compares Fortify, rapid prototyping, and

The mold tool geometry used to compare prototyping methods.

conventional aluminum processes. While it’s important to note that an aluminum mold will last for 1 – 10,000 parts, 3DP tools are much less expensive and provide more flexibility when it comes to design changes or part complexity. For example, injection molded parts with sharp corners, thin ribs or undercut features will generally be more expensive because it requires a secondary process called EDM machining. Complexity comes free with Fortify, and nowhere near as costly or problematic. 

Analyzing the 6 x 4 x 2 Model

Process 25 Parts 50 Parts 75 Parts
Rapid Prototyping $1,250 $2,500 $3,750
Fortify IM Tool $300 + Material Cost $300 + Material Cost $300 + Material Cost
Aluminum IM Tool $5,000  + MC $5,000  + MC $5,000  + MC

The table above compares several methods of producing multiple prototypes or low volume production. As you can see, rapid prototyping of multiple parts starts to get relatively expensive as the quantity increases, but is still nowhere near the cost of an aluminum tool for less than 100 parts. However, the Fortify IM tool is significantly less expensive and just as capable to mold parts with the appropriate end-use materials. In fact, an engineering team can redesign a prototype injection mold tool with Fortify over 15 times for the same cost as a singular aluminum mold. 

Where can I learn more?

Historically, 3D printed tools were considered a gimmick and unqualified due to a lack of material capabilities. They were brittle and unable to withstand the high temperatures of molding, leaving many engineers without a viable alternative. That is, until Fortify presented a technology that is flexible, inexpensive, and strong enough to mold parts in end-use materials. Ceramic fiber reinforced materials are revolutionary for the prototype injection mold market that enables a true bridge-to-production tool that will save engineers time and money, without sacrificing quality. 

Inject a variety of thermoplastics that include polycarbonate, nylon 66, ABS and POM from a Fortify mold that is ~90% cheaper than aluminum. The conventional IM tooling process can take up to eight weeks to get parts delivered, imagine having those same parts within days? Fail fast and fail often by quickly redesigning prototype IM tools and testing parts immediately, getting to market faster than ever before. 

If you’d like to learn more about how you can maximize prototype injection molding with Fortify, contact us today.