Overcoming obstacles in additive manufacturing space technology

Additive manufacturing (AM), commonly known as 3D printing, has great potential to reduce material waste and product assembly time in the space industry, while also increasing design freedom and innovativeness. However, the method has obstacles. A new thesis in product innovation proposes a framework for design support to tackle these obstacles.

AM builds three-dimensional objects layer by layer from a digital model, unlike traditional subtractive manufacturing, which removes material from a block.

There are many different forms of AM. The method investigated in the thesis is Laser Powder Bed Fusion (LPBF). LPBF works by spreading layers of metal powder across a build platform and selectively melting them with a laser to form each part’s cross-section. The platform is then lowered, and the process is repeated until the final component is built.

“In theory, LPBF means that you can use exactly the right amount of powder you need, thus minimising material waste”, says the author of the thesis, Didunoluwa Obilanade.

Expand design freedom

For complex products like rocket engines, AM can simplify production, shorten assembly time, and expand design freedom.

“You can have a lot more iteration in an additive manufacturing design process than in a traditional one. It is also easier to make prototypes for testing. Making it easier to modify designs late in the product development process.”

However, in the LPBF process, excess heat seeps into the surrounding powder, melting unwanted powder and causing it to adhere to the part's surface, resulting in a rough surface. This roughness weakens the material's fracture properties. Removing roughness will strengthen the material, but it will also decrease the cost benefits of AM, as it will require more material and longer manufacturing time. Some roughness can be acceptable. The problem is well known in the field, as highlighted by a literature study within the thesis, which shows the limited guidance available for surface-related uncertainties in AM design. Therefore, an important part of the thesis involves developing a design method to understand the balance between roughness, the removal of roughness, and its impact on material properties.

Sharing of data

The thesis presents a study comprising in-depth interviews with 20 engineers, CEOs, designers, and technicians from the space and aeronautical industry across a wide range of countries. Several of the interviewees call for improved data collection of metallurgical properties and the sharing of data between companies to address AM design issues.

A common AM design support is the use of simulation tools. However, designers are dependent on different software in the simulation process. File transfer between software leads to data loss. Interviewees expressed a desire for an integrated software solution that manages the whole process.

Based on a literature review and a real-life rocket engine product case study, Didunoluwa Obilanade has developed an 11-point framework for evaluating and improving design support. The thesis also presents a seven-stage model of AM aerospace product design, integrating design and manufacturing to highlight the iterative feedback benefits of AM.