Development and Custom Machining for Diver Propulsion Device

Project Background

Our client, a designer and developer specializing in maritime sector products, focuses on customizing and creating various underwater devices and equipment for end users.

Recently, they designed a new propulsion device for divers. This propulsion system features low-noise brushless motors to minimize the impact on marine organisms and their auditory systems. It also employs lightweight components to deliver powerful propulsion while keeping the overall device weight low.

Although the device is mainly designed for underwater photography and diving enthusiasts, the designer envisions a broader application: “If this propulsion device works well, I would like to adapt it for underwater robotics and automated underwater rescue operations.”

This case study will introduce the external components of the diver’s propulsion device manufactured by WayKen.

Machining Requirement Analysis

Underwater propulsion systems are widely used in marine exploration, underwater operations, diving tourism, and other fields. Generally, their core requirements typically include high performance, lightweight construction, waterproof and corrosion resistance, and intelligent control. These are equally important for this design, along with ensuring smooth curved surfaces to minimize drag and enhance efficiency. Here are the manufacturing requirements of diver propulsion device.

• High Performance: The propulsion device is equipped with a highly efficient brushless motor that adjusts drive torque based on water pressure and resistance, ensuring propulsion efficiency.
• Lightweight: Constructed from high-strength, lightweight material, the design needs to reduce overall weight and size, making the device portable and easy to use.
• Waterproof and Corrosion Resistance: To withstand harsh underwater environments and maintain stable, long-term operation, the propulsion system requires excellent sealing performance and corrosion resistance.
• Intelligent Control: Pressure and temperature sensors are integrated into the device to monitor water conditions in real-time. This allows for automatic adjustments to improve safety and user comfort.
• Optimized External Surface: Smooth and well-designed surfaces play a key role in enhancing propulsion efficiency and minimizing drag. By optimizing the housing’s external surface, the propulsion system can better utilize water flow, increase efficiency, and reduce resistance.

For the newly designed diver propulsion housing, the client prioritizes the external surface, lightweight construction, and corrosion resistance. Consequently, for manufacturers, machining processes should focus on curved surface optimization, thin-wall machining, and surface treatments.

Focus and Solutions for Production

The project was chosen AL6061-T651 to manufacture the external housing of the underwater propulsion device. This material undergoes heat treatment to relieve internal stresses and reduce the risk of cracking. Here’s how WayKen custom machining solutions according to the machining requirements of the propulsion device.

Surface Machining

For machining the impeller of the propulsion device, WayKen utilized the advanced capabilities of the high-precision JDGR400T 5-axis machine. This technology enabled the processing of its complex three-dimensional curved surfaces, ensuring precision and surface quality.

In the specific milling route, WayKen mainly used ball-end milling for roughing, semi-finishing, and finishing stages to achieve optimal results:

• Roughing: A higher spindle speed and feed rate were used to rapidly remove excess material. A machining allowance was left to prepare for the subsequent semi-finishing and finishing processes.
• Semi-Finishing: Using ball-end milling again, the impeller blade was refined further with consistent spindle speed and feed rate, setting the stage for precision finishing.
• Finishing: A smaller diameter ball-end mill was utilized in this stage. The spindle speed was increased, and the feed rate was reduced compared to earlier processes. This approach minimized friction and heat, effectively reducing surface roughness and enhancing dimensional accuracy.

During the machining, we also pay attention to optimizing the cutting parameters, such as cutting speed, feed, and the use of coolant, to avoid excessive thermal damage.

Thin-Walled Machining

To make the underwater propulsion device lightweight and portable, the designers minimized the wall thickness wherever possible. This design could reduce the device’s weight, improve buoyancy, and provide sufficient space for internal components. However, the housing walls cannot be too thin, as they must withstand the pressure exerted on the top and impeller during operation. In this propulsion housing part, the wall thickness is designed between 1-3 mm.

However, for the overall housing, the wall thickness is still relatively thin. To control deformation, WayKen optimized the cutting path, carefully adjusted spindle speeds, and cutting parameters, and selected the appropriate coolant.

In addition, WayKen’s temperature-controlled workshop could maintain consistent temperature and humidity levels. It helps to minimize thermal deformation caused by environmental fluctuations, ensuring high machining quality and precision.

Surface Treatment

Underwater environments are harsh, with high salinity, humidity, chloride ion content, and corrosive atmospheric conditions. These factors can degrade the oxide layer on aluminum surfaces, exposing the material to severe corrosion and significantly shortening the device’s lifespan.

To enhance the corrosion resistance of propulsion device components, methods such as anodizing and protective coatings are commonly used. For this project, the client required a more durable protective layer. So WayKen recommended choosing hard anodizing to provide a higher and stronger layer and long-lasting corrosion resistance for the propulsion parts.

Feedback and Future Plan

We successfully completed and delivered the diver propulsion device components, which the client received and integrated with other components. Their feedback: “These assemblies look great, though we’ll proceed with further functional and environmental testing. Many thanks to WayKen for their quick response and support. We look forward to future opportunities to collaborate with such a reliable supplier.”

At WayKen, our team of professional engineers and CNC machinists specializes in bringing your designs to life with precision and expertise. Share your design with us, and we’ll provide the best solution for your CNC machined parts.