Custom Spacecraft Propellant Tank for Aerospace

Project Background

Propellant tanks are an important component of spacecraft propulsion systems. It is used for storing and delivering propellants under severe space conditions. In recent years, technological advancements have driven the development of innovative products and systems in the aerospace industry.

As a result, the functional requirements for propellant tanks have become increasingly demanding. These tanks must be constructed from lightweight, durable materials and undergo rigorous validation during the product development phase to ensure their reliability and performance.

To achieve high-quality results during development, partnering with an experienced and skilled production team is essential. Recently, WayKen successfully produced specialized spacecraft propellant tanks for the customer. Let’s explore how WayKen supported the production of this advanced component.

Structure Analysis of Titanium Propellant Tank

Before sharing the processing of this propellant tank, let’s first look at its basic structures. The tank consists of two half-circle arc components that must be strictly assembled. To ensure assembly precision, the flatness tolerance for these components is set at a tight 0.02 mm. Additionally, as the propellant tank needs to integrate with other equipment, the surface profile tolerances of the arcs are also highly precise.

As a critical component of the aircraft propulsion system, the propellant tank must meet high lightweight requirements. Lightweight designs help reduce launch weight, extend launch range, and lower costs. To achieve this, the design of the tank focused on two key aspects:

• Material Selection: Titanium alloy, known for its low density and lightweight, was chosen as the raw material, making it ideal for this application.
• Structural Design: The material usage was minimized by designing the center arc structures with ultra-thin walls, measuring just 0.8 mm for both components.

This combination of precision and lightweight design ensures the propellant tank meets the demanding requirements of aerospace applications.

Custom Machining Solutions for Key Features

Based on the structural analysis above, we have identified the following machining aspects requiring attention.

Machining Arc-Shaped Thin-Walled Structures

To ensure the propellant tank can be assembled accurately, the wall thickness of the arc-shaped structures is exceptionally thin, with strict surface profile tolerance requirements. Minimizing deformation during machining is critical to achieving this thin feature.

Although CNC turning is ideal for circular structures, there are red structures with different normal directions on the side that cannot be machined through turning. Furthermore, due to the structure’s shape, precise clamping on a lathe is challenging, making CNC milling this structure and feature the ideal choice.

In addition, we should take multiple tests to adjust the tool path and cutting speed to minimize deformation before machining.

Machining Assembly Surfaces with High Flatness Requirements

Accurate assembly of the two arc-shaped components is key to the propellant tank’s functionality. Any assembly inaccuracy could compromise testing and render the tank unusable. Therefore, the flatness requirement for these surfaces is set at a stringent 0.02 mm.

At the same time, deformation control is also essential to achieving this level of flatness. While a grinder can easily meet the flatness requirement, it is unsuitable for machining the surface due to the presence of raised steps. Instead, a two-step fine milling process is employed. Leaves an exact allowance for the next step in the first fine milling. Then complete the machining process to achieve the required flatness.

Considerations When Machining Titanium Alloy

Titanium alloy, selected for its high strength, lightweight, and corrosion resistance in this project, presents several machining challenges due to its poor machinability.

• Tool Wear: Titanium’s high cutting resistance causes severe tool wear, increasing the risk of deformation. To address this, coated carbide or ceramic tools are used, and cutting parameters, such as lower speeds, are optimized to enhance machining efficiency while reducing deformation.
• Low Modulus of Elasticity: Titanium’s low elasticity increases the likelihood of part deformation during machining, especially for thin-walled or complex structures. To mitigate this, specialized fixtures are designed to improve clamping force and reduce material-induced deformation.

Achieving Excellent Surface Quality and High Precision

As the picture shows, the final propellant tank looks great. To ensure customer specifications for surface profile and flatness were met, WayKen’s inspection department carried out a careful inspection with CMM. The inspection report showed that the tank fully complies with the required surface profile and flatness requirements.

Feedback

After receiving the titanium propellant tank, our customer carried out secondary inspections, trial assembly, and functional testing. Their feedback was positive: the spacecraft’s titanium propellant tank looked perfect, and the testing proceeded smoothly with WayKen’s support.

At WayKen, our experienced engineering team is expert at developing tailored CNC machining solutions for high-precision components, ensuring we meet the diverse requirements of our customers with excellence.