Magnesium vs. Aluminum Prototyping for Validating SAR Aircraft Imaging Device

About the Project

With the growth of shipping and fisheries, demand for maritime search and rescue (SAR) has steadily increased, leading to the development of specialized SAR aircraft. These aircraft are equipped with advanced radar and thermal imaging devices, capable of detecting objects in low-visibility conditions.

Thermal imaging equipment significantly improved SAR efficiency and reduced false alarms. Today we will present prototypes in two different materials of a thermal imaging inspection device for maritime SAR aircraft. Our customer expected to optimize prototyping by exploring different materials and processes to find the best solution for future low-volume production. Let’s see how WayKen supported this prototype validation!

Meeting Diverse Validation Needs in the Prototype Stage

Validating prototypes is essential before full-scale production, as it helps determine the most suitable materials, surface treatments, and processing solutions. Given the device’s usage in humid maritime environments, key validating includes lightweight construction, high strength, and corrosion resistance.

1. Magnesium vs. Aluminum Material Validation

The customer required components to be strictly controlled in weight, with each part weighing no more than 30g, aiming for the lighter the better. For this project, WayKen suggested two metal alloys. Magnesium alloy (AZ31B), with a density of just 1.8 g/cm³, is an ideal lightweight material for aerospace applications but lacks the strength and corrosion resistance of Aluminum alloy (6061-T6).

In contrast, Aluminum alloy (6061-T6) offers high strength and corrosion resistance but is heavier. Therefore, we should determine which is the best material for this device through prototype validation between these two alloys.

2. Surface Treatment Validation

Thermal imaging device components for maritime search and rescue aircraft are used in humid environments. It needs high corrosion resistance. Considering the properties of both materials, surface treatment is required to improve corrosion resistance. It is also an important consideration during the prototype production stage.

The customer also requested it would be better if WayKen could provide suggestions for the surface treatment of different materials. Based on our expertise, we recommended optimal surface treatments for Aluminum alloy (6061-T6) and Magnesium alloy (AZ31B).

2.1 Hard Anodizing for 6061-T6 Aluminum

For Aluminum alloy (6061-T6), we recommend hard anodizing, which forms a thicker, protective layer compared to standard anodizing and significantly improves corrosion resistance. Given the precision requirements, however, an excessively thick layer (≥25μm) could impact part tolerances, so we should carefully control coating thickness for optimal protection and accuracy.

2.2 Plasma Electrolytic Oxidation for Magnesium AZ31B

Magnesium alloy (AZ31B) is more prone to corrosion than aluminum, making plasma electrolytic oxidation an ideal treatment. This process enhances thermal diffusivity, electrical insulation, wear resistance, and corrosion resistance, making it the ideal option to improve durability for Magnesium alloy (AZ31B) parts in harsh maritime conditions.

Analysis of Processing Challenges

The machining challenges of these prototype verifications are mainly divided into two aspects: one is how to develop different machining route for different materials; the other is the machining of complex structures with high precision.

1. Process Development for Different Materials

Developing the right machining route for each material before production is important. Aluminum alloy 6061-T6 alloy with excellent machining properties that can machine the components precisely and quickly.

However, Magnesium alloy (AZ31B) is more challenging to machine due to its reactive properties. The heat generated during machining can ignite magnesium debris, posing a fire risk. We need to carefully adjust the tool feed rate to reduce tool heat and minimize the possibility of chip ignition.

2. Analyzing Machining Challenges

In order to further show the machining points of the components, we will introduce the machining considerations for one of the main components in this paragraph. It plays a transmission role in the operation of thermal imaging devices for maritime search and secure aircraft.

2.1 Part Structure

Firstly, the 3D drawings show that this part has a very small size and two large external threads of M28. The maximum diameter is only 32.4mm. And there are many small steps on the exterior surface. Furthermore, the surface roughness requirement for the whole exterior structure is very high. Secondly, there is a large cavity inside the component with the shape of big on top and small on the bottom. It is difficult to be machined by ordinary cutting tools.

2.2 Machining Considerations

Based on the previous analysis of the thermal imaging device part’s structure and tolerance requirements, several key machining aspects should be focused.

2.2.1 High Surface Finish and Tight Tolerance Requirements for External Structures

The drawing specifies high precision demands for surface roughness and geometric tolerances, with an overall surface finish requirement of Ra 0.4μm and a tolerance of 0.02mm for perpendicularity, parallelism, and runout. CNC turning is ideal for achieving this level of precision, as it is more stable than CNC milling and can meet these demanding specifications. In the turning process, we use single-crystal cutting tools for the exterior surfaces and large external threads, ensuring both machining accuracy and a superior surface finish of Ra 0.4μm.

2.2.2 Machining Irregular Interior Structures

The internal cavity features a tapering structure, specified with a surface roughness of Ra 0.4μm. CNC turning will also be used for this cavity, but due to its unique shape, a custom cutting tool is necessary to achieve the required precision and surface quality.

Inspection

In addition to the main component, the other thermal imaging device parts also require tight geometric tolerances. To ensure inspection accuracy for these small components, we use a Coordinate Measuring Machine (CMM), capable of measuring strict tolerances down to 0.002mm. This ensures all inspection data meets the quality standards for the thermal imaging devices for maritime search and rescue aircraft.

WayKen is Your One-stop Machine shop for Prototyping

As a professional rapid prototyping manufacturer, WayKen has an expert team to provide one-stop machining services, including material selection, surface treatment, and cost-optimized validation for your prototypes, ensuring the best support as you move toward low-volume production.