Case name: Injection Mold Making for Unmanned Aerial Vehicle’s (UAV) Parts

Struggling with UAV Frame Strength? How ACO Mold Solved Impact Failures by Switching from PP to PA66

Introduction: The Hidden Cost of Brittle Drone Frames

Are fragile drone frames causing frequent crashes and high replacement costs? You’re not alone. Many UAV developers face a critical challenge: balancing lightweight design with the structural integrity required for real-world flight.

In this case study, we break down how ACO Mold helped a client overcome catastrophic structural failures during flight testing. By executing a strategic material switch and mold optimization, we delivered a robust, production-ready solution that didn’t compromise on weight or durability.

1. Project Overview & Initial Specifications

Recently, ACO Mold completed a project involving custom injection molding for Unmanned Aerial Vehicle (UAV) components. This case study details the end-to-end process of manufacturing plastic frames and covers, highlighting our expertise in Design for Manufacturability (DFM)​ and material optimization.

The client required two core components for the plastic body enclosures of a new commercial UAV model. To meet the estimated annual production volume of 20,000 units (20K), we determined that separate molds were necessary to ensure stable mass production capacity, avoiding the pitfalls of low-volume prototyping. The initial specifications were set for high-volume production.

Component	UAV Frame (Main Body)	UAV Cover (Shell)
Dimensions​	92.1 × 92.1 × 27.35 mm	90 × 45 × 10 mm
Initial Material​	Polypropylene (PP)	Polypropylene (PP)
Surface Finish​	EDM Texture	EDM + Pad Printing
Target Volume​	20,000+ Units	20,000+ Units

2. Mold Design & Tooling

Based on the part geometry, we engineered distinct mold structures for optimal filling:

• Mold Type:​ 2-Plate mold for the Frame; 3-Plate mold for the Cover.
• Gate Type:​ Side Gate.
• Cavity Number:​ 1 cavity per mold.
• Injection Machine:​ 160-Ton.

Prior to machining, our engineering team conducted a thorough DFM analysis, verifying critical details such as parting lines, gate locations, and ejection systems with the client to mitigate risks early.

3. The Prototyping Challenge: T1 & T2 Trials

The mold manufacturing was completed within 4 weeks. However, the initial T1 trial revealed common injection molding defects: noticeable weld lines​ and sink marks.

• Solution:​ We modified the mold sleeve pins to address the sink marks.
• T2 Result:​ After modifications, oil treatment, and color painting, the aesthetic appearance met requirements. The client proceeded with assembly and analog flight experiments.

4. Engineering Change: Upgrading to PA66

During the T2 flight testing phase, the client identified a critical functional issue: the impact strength of the original Polypropylene (PP)​ material was insufficient for the drone’s operational demands.

Initially, PP was selected for its low density and cost-effectiveness. However, during analog flight experiments with the power system installed, the UAV exhibited critical flaws:

• Structural Flexing:​ The frame showed excessive deflection during high-speed maneuvers.
• Impact Failure:​ Minor collisions and rough landings resulted in cracks and breakage.
• Business Risk:​ For a commercial drone intended for agriculture or surveying, this level of brittleness was unacceptable.

Root Cause:​ While easy to mold, PP has a low Izod impact strength (<5 kJ/m²), making it unsuitable for high-stress structural components.

To solve this, ACO Mold recommended a material switch:

• From:​ PP (Polypropylene)
• To:​ PA66 (Nylon)​ – Known for superior mechanical strength and heat resistance.

Simply swapping materials wasn’t enough. Our team executed a rapid Design for Manufacturability (DFM) update focusing on three key areas:

A. Material Selection: PP vs. PA66

We recommended switching the frame to PA66 (Nylon 66), known for its exceptional mechanical strength and fatigue resistance.

B. Shrinkage & Tolerance Adjustments

Unlike PP (shrinkage ~1.6%), PA66 exhibits a higher shrinkage rate (~1.8–2.2%). We recalculated the mold cavity dimensions to ensure the final parts maintained tight tolerances after cooling.

C. Wall Thickness Optimization

We identified critical stress concentration points and strategically increased the local wall thickness from 1.5mm to 2.0mm. This reinforced the frame without significantly increasing the overall weight.

5. Final Validation & Mass Production

The T3 samples, molded in PA66, passed all performance tests. The client approved the design, and we immediately proceeded to mass production.

6. Conclusion & Results

This project demonstrates ACO Mold’s capability to adapt quickly to engineering changes and deliver robust solutions for the UAV industry. By switching from PP to PA66, we ensured the drone met the required durability standards. The final UAV frame demonstrated superior impact strength, ensuring the drone could withstand the rigors of daily operations.

Ready to Engineer Your UAV Success?

Choosing the right material and mold design is a make-or-break decision for your drone’s performance. Don’t let material limitations ground your project before launch.

Whether you need DFM analysis, material selection consulting​ (PP, ABS, PA66, PC), or rapid tooling, ACO Mold is your strategic partner.