Machining and Application of Thin-walled Aluminium Shells with Deep Cavities

Products Introduction

Navigational safety monitoring is necessary when shipping in the ocean. However, it is very difficult to monitor the safety of ocean navigation, especially at night or in bad weather. Even professional mariners cannot accurately find out the risk in time. The application of thermal imaging systems has enabled maritime navigators to identify navigational aids, beacons, logs, and other floating objects in the water, enabling accurate and timely judgment of potential hazards and ensuring navigational safety.

Jason is an industrial designer in a start-up that designs and develops imaging systems in the US. Recently, he and his team designed a customized housing for ocean thermal imaging systems and wanted to find a professional manufacturer to meet their requirements and produce them.

Machining and Surface Finishing Analysis

The team mentioned that they had completed the design of the housing for this ocean vessel imaging system, but they had no experience in how to better integrate their design with machining feasibility. Here WayKen can help.

1. Material Selection

Jason mentioned that this device is going to be used on ships but the climate at sea is humid. Thus the housing needs to be highly resistant to corrosion. In addition, the weight of the housing makes up the majority of the entire imaging system device. Lightweight, strong, and corrosion-resistant metal for the housing is also required.

AL6061-T6 material is lighter while having higher material strength and good corrosion resistance. It is widely used in the machining of housings in various industrial machines and is a good choice for the housing of this ocean navigational imaging system device.

2. Methods to Improve the Corrosion Resistance of the Housing

To further improve the corrosion resistance of the housing of the ocean navigation imaging system device, WayKen recommends a surface treatment on the inside and outside of the housing.

The exterior side (black side) of the housing can be hard anodized in black. Hard anodizing improves the corrosion resistance of aluminum parts and gives a perfect surface appearance. On the other hand, the inner surface is the assembly surface (red surface). In order not to affect the assembly surface, we recommend chromate treatment for the inner surface. The chromate treatment produces a thin protective film that not only enhances the corrosion resistance of the inner surface of the housing but also does not interfere with assembly.

As there are some threaded holes in the housing, WayKen also considers masking all the holes first when doing the surface treatment to keep their function. Jason was satisfied with the machining solutions. So, this customized housing of thermal imaging system device for ocean vessel navigation was put into production.

Imaging System Device Housing and its Machining Route

Let’s analyze the structure of this housing. As we can see from the 3D drawing, this part is housing with different directions and deep cavities. There are strict requirements for assembly and a short lead time.

If parts were machined by 3-axis CNC milling, multiple clamping is required to complete the machining of different surfaces in different directions. In order to ensure accuracy and improve the efficiency of the machining, WayKen finally decided to use 5-axis CNC milling to produce. This process can rotate and machine different direction surfaces of a part by one clamping. Machining by 5-axis CNC milling can also avoid multiple clamping to improve the machining accuracy and efficiency of this housing.

Machining Key Features and Solutions

Before production, our team evaluated the drawings carefully. During the evaluation process, we found some features that need to be focused on when machining as well as serval machining key points.

1. Important Assembly Surfaces

The following red surface is an important assembly surface. In order to ensure a precise assembly, the surface roughness of the red surface needs to be Ra1.6μm. Thus, this assembled surface should be machined by fine milling.

In addition, a sealing groove was designed (green surface) since the assembly surface is required to seal. In order to ensure the sealing, the sealing groove also needs to be precision milled. After milling, a sealing silicone ring will be installed in the groove, so that a perfect seal can be achieved.

2. Deep Cavity and Thin Wall Thickness

This housing has a very large number of parts to be assembled inside. The volume of the housing is also very large, with a depth of 78.5 mm. At the same time, in order to further reduce the weight of the housing, the design of the housing with a wall thickness of only 1.5 mm.

When machining such housing with deep cavities and thin wall thickness, two machining risks will be faced. The wall thickness will be easily broken and the housing will have deformation. To avoid these risks, the housing parts need to be relieved of stress to reduce the frequency of vibration before machining At the same time, the cutting speed should be reduced, and the tool path should be constantly adjusted and tested. Finally, the most suitable tool path is selected.

3. High Threaded Accuracy Requirements of Holes Distance

This vessel navigation thermal imaging system device needs to be secured and fixed to a positioning device when performing safety inspections precisely. Thus the accuracy requirements of the distance between the threaded holes on the green face, and the distance between the threaded holes and the bottom surface are very demanding. Both distances need to be ±0.025mm, and in order to meet these requirements, the two threaded holes need to be precision milled so as to ensure accurate assembly.

Feedback and Future Plan

Thanks for our customer’s understanding and positive cooperation. The customer feedback in the email: this is the first time we worked with WayKen and this is a pleasant experience. WayKen is a very professional CNC machining manufacturer and gave us a lot of advice on the machining feasibility so that we could validate our design successfully. It is a perfect partner for us now and in the future!