Effective prototyping is the cornerstone of successful plastic product development. Here’s a practical approach to help you translate your designs into reality:
1. Proof of Concept with FDM/SLA
The first steps of development to reach a proof of concept require methods that are quick and relatively inexpensive to test basic hypotheses. The aim is mostly to find solutions for specifications and open design challenges.
It is advisable to use either FDM (Fused filament fabrication) or SLA (Stereolithography) 3D printing to create your initial prototypes. Many times, these methods can even simulate metalworks, although they resemble plastics more accurately. Due to the high precision of SLA, it is better suited for elements like small threads, whereas FDM is better for cruder parts.
Using these methods allows frequent iteration, making adjustments with each version until your prototype functions exactly as intended.
It's crucial to perfect critical design elements like snap fits, threads, and moving parts at this stage. If your design doesn’t work, avoid relying on “excuses” such as expecting better materials later to fix design flaws. Instead, solve design problems with as many FDM and SLA iterations as needed.
If possible, test your design in conditions as close to real-life use as possible. For example, conduct an in-house drop test—although it might break, you will learn a lot from it. You can easily reprint and iterate on your parts.
Another example is to test your prototype with real end-users. Engineers designing their own products tend to be subconsciously gentle with their creations—it’s their "baby." Getting unbiased user feedback is invaluable.
Engage with your mold maker early to gain valuable insights that can optimize your design and prevent costly revisions down the line. This applies to parts intended for metalworks or sheet metal as well—engage with the end suppliers early.
2. Validate with Silicone Molds
Once you have a functional 3D-printed prototype, produce at least five identical units using silicone molds. For an assembly of multiple parts, this allows you to test different combinations of identical parts to assess consistency and refine tolerances.
For example, if your project consists of three parts, you would have 5³ = 125 combinations to test as an assembly. Testing multiple combinations is essential, as it reveals subtle variations that can significantly impact assembly. Choose the number of combinations to test based on your project requirements. Ensure all parts fit perfectly across different combinations.
If they don’t fit, don’t worry—this is natural. Engage with your mold maker again to understand potential tolerances during the final mold-making step. If needed, go back to step 1 and redesign to achieve perfection. Be prepared for this iteration when planning your project, as it will likely happen.
3. Transition to Injection Molding
Only when you have at least five perfected working prototypes from randomly chosen parts in your assembly should you move on to mold making.
Mold making is not the main goal of this article, but here are a few tips:
Treat your mold maker as a consultant and expert in their field. Send your prototypes, along with the 3D files and drawings, to the mold maker.
Explain as much as possible about the project, including quantities and pricing of the entire product, even non-plastic components, as these can influence mold design.
You likely won't get the molds perfect on the first round, which is natural. This process is known as T0 injections. Plan for this in terms of timeline and resources, as well as for parts themselves. This is called steel-safe design and can be counterintuitive to prototyping. Consult your mold maker about this.
Remember, there are many other factors to consider!
Here’s a table summarizing the stages:
Stage | Method | Goal | Key Actions |
1. Proof of Concept | FDM/SLA 3D Printing | Validate functionality | – Iterate designs rapidly – Perfect critical elements (snap fits, threads, etc.) – Consult with mold maker early |
2. Validation | Silicone Molds | Assess consistency and refine tolerances | – Produce at least five identical units – Test multiple combinations of parts in assembly – Identify and address subtle variations – Consult with mold maker on tolerances |
3. Production | Injection Molding | Final production | – Proceed only after achieving five perfected prototypes from silicone molds |
Good luck with your development projects!
More to come in the next article!
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