Freeform injection molding is the ‘next frontier’ of molded parts and products.

When we talk about plastic injection molding, steel molds immediately come to mind. Tooling like this dominates the market and churns out consistently-made parts in the millions every day around the world.

But did you know that it’s possible to use 3D printing to rapidly create mold tooling that can be used to injection mold parts made of plastic, silicone, metals, and even ceramic? In this way, you get the speed of 3D printing and the numerous benefits of injection molding.

What is freeform injection molding?

Freeform Injection Molding (FIM) was originally developed by Danish company Addifab and with equipment pioneered by Nexa3D. It is a revolutionary approach that offers amazing prototyping and, in some cases, short production run capabilities. It combines the benefits of 3D printing with traditional injection molding, offering significant advantages in speed, cost, design freedom, and environmental impact.

A 3D printer quickly produces the mold from a special resin that, if needed, can be dissolved in order to extract the part. The injection molding process then takes place as normal, with the chosen polymer being injected into it to create the desired part.

Image credit: Addifab.com

The mold’s useful lifespan varies from 1 part to a few dozen parts, depending on the polymer, the part geometry, and a few other factors.

This is very different from traditional injection mold tooling made from hard steels durable enough to last for hundreds of thousands of shots, which will commonly take around 6 weeks or more to fabricate & trial.

Interestingly, freeform injection molding can produce a silicone, metal, or ceramic part, too. That opens up a lot of possibilities.

Freeform injection molding’s key benefits

3D printed molds drastically reduce lead times

Gone are the days of waiting weeks or months for machined steel molds to be fabricated. With FIM, you can now get a few plastic parts that are essentially similar in both material and physical properties to those created by traditional injection molding… in a matter of a few hours if the part can easily be de-molded, otherwise in a couple of days. That allows design teams to accelerate their development cycles.

Have you already got tooling fabricated and then revised, losing weeks and thousands of dollars? Using FIM allows you to stop rolling the dice. You can now fully validate the product design, with parts that have the same physical characteristics and made from the same polymer as production parts, before you pull the trigger and make the hard steel molds.

You’ll have more design freedom

FIM unlocks design freedom. Unlike traditional methods and their limitations, FIM allows you to create complex geometries with intricate features, pushing the boundaries of innovation. Here’s an example of one such complex part, a flip-top bottle cap made of recycled PP, and its dissolvable mold:

Image credit: Nexa3D

Contrary to vacuum casting, FIM allows you to design parts that would require side actions. You can still “eject” the part by dissolving half of the mold if it doesn’t allow for easy de-molding.

And, in contrast with a hard steel mold, making experimental changes that may fail is a much lower risk. Doing so in a prototype 3D printed mold which can be remade in hours is a game-changer for creativity and the ability to test designs.

Material versatility

Nearly all materials commonly used in traditional injection molding can be injected into freeform molds. That’s critical to ensure prototypes accurately reflect the final product’s physical properties and performance.

This is a key benefit in contrast with 3D printing prototyping, which produces parts made of a much narrower range of polymers (depending on the technology).

More sustainable

FIM is a more sustainable choice than CNC machining a part out of a block of plastic or metal. Using FIM generates less material waste and fewer carbon emissions (75% less according to Addifab), making it an environmentally friendly option for product developers and manufacturers looking to reduce their environmental impact. In addition, it can be much cheaper than CNC machining.

What does the freeform injection molding process look like?

This video from Addifab illustrates the 3 key steps in the process: 3D print, injection mold, and dissolve.

Note: in many cases, dissolving a part of the mold is not needed. That’s only needed when the geometry of the part prevents it from being ejected.

Why dissolvable tooling is so innovative

Unlike traditional steel or aluminum molds, FIM molds are made from a special resin designed to dissolve in a solution after use. This eliminates the need for intricate mold removal procedures, significantly simplifying the post-injection workflow and speeding things up.

Dissolvable tooling benefits

When dealing with complex geometries and intricate parts that require features such as undercuts or internal channels, FIM really shines:

• Conventional Molding Challenges
  To achieve these features, conventional methods often rely on complex mold designs such as sliders, which add significant cost and complexity to the mold making process. Additionally, removing parts from molds with sliders can be challenging and requires careful engineering to avoid damaging the part.
• FIM with Dissolvable Tooling
  With FIM, the dissolvable nature of the mold eliminates the need for sliders altogether. The 3D printing process can directly create these complex geometries within the mold itself. Since the mold dissolves after use, there’s no need to worry about part removal through intricate mechanisms.

This interesting video from 3D printing nerd, clearly demonstrates the FIM process using Nexa3D hardware, dissolvable molds, and parts that can be created:

Which resin is suitable for FIM?

Freeform mold tooling utilizes a patented dissolvable resin to create the mold. Here’s what makes this resin special:

• Tailored for Dual Functionality: This resin has the capability to be both:
  • Printable: The resin has viscosity and flow characteristics for techniques like SLA or DLP. It also has the ability to solidify precisely when exposed to UV light during the 3D printing process, ensuring accurate mold features.
  • Mold-Worthy: It can withstand the high temperatures (often exceeding 200°C) encountered during injection molding without warping or degrading. This ensures the mold can endure multiple cycles of molten plastic injection.
• Dissolvable on Demand: A key feature is the resin’s ability to dissolve after its job is done. This allows the mold to be removed from the molded parts using a chemical bath. This eliminates the need for complex mold disassembly techniques and enables easy reuse of the internal space for subsequent molds.

3D printed mold durability

Where durability is concerned, FIM will not replace traditional tooling. However, the 3D-printed mold may be able to withstand up to a few dozen shots in its useful life time, although the number is dependent on the part design and the polymer used.

Producing a few parts quickly is the key feature. FIM molds are best suited to producing single prototypes or small runs, up to maybe a few dozen parts in certain cases as we just mentioned. For production runs of larger amounts, steel tooling is preferable due to its far superior durability. That being said, because 3D printed molds can produce parts with production polymers and at a similarly high quality, they’re a great complement to hard tooling, perhaps more likely being used during the prototyping and design verification stages to provide peace of mind that the part can feasibly be injection molded and reach expectations, or the flexibility that hard steel doesn’t offer to try out new ideas.

What is freeform injection molding best suited to?

Using 3D printed mold tooling like this is particularly beneficial in certain scenarios:

• It is ideal for low-volume production runs and functional prototyping
• Perfect for rapid design iterations and testing new concepts
• Great for testing design concepts with production intent polymers
• Benefits most industries: consumer electronics, medical, automotive, aerospace, etc.

Summary

The decision that ‘now is the right time to make the injection mold’ always carries a risk. Freeform Injection Molding (FIM) allows for rapid and affordable design iterations that can be used to test more options and validate a given design much faster and cheaper.

Freeform injection molding key takeaways:

• Rapid Design Iteration: Move from concept to prototype in record time.
• Unmatched Design Freedom: Create complex geometries and push the boundaries of design.
• Cost-Effective Molds: Reduce prototyping costs and explore new ideas with minimal investment.

Get help

First, read: The Plastic Injection Molding Process: Top Questions and Answers for answers to the questions we’re usually asked about plastic injection molding.

Then, if you’re interested in this type of molding for your plastic parts, we can help you at our plastic injection molding facility. Take a look and get help here.

P.S.

We’ve partnered with the manufacturer Nexa 3D to become the first company in Asia to offer this technology to our customers: