Among the many vulnerabilities that the coronavirus pandemic exposes has been the fragility of globalised supply chains amid lockdowns and travel bans. As companies and governments try to tide through the storm on the onset with stop-gap measures, the crisis may well bring about a permanent, or at least gradual shift towards alternative supply chain solutions and production methods.
In the aviation industry, for instance, one way to address supply chain issues would be to rethink the production process by leveraging the capabilities in 3D printing or additive manufacturing (AM), which at present is used for little more than prototyping and non-critical aircraft parts. Although AM has been part of aircraft production for years, it has yet to enjoy a commercial market on a larger scale partly due to the relative absence of established standards and performance track records.
With a keen eye set on AM and its potential as a print-on-demand at point of need for producing aircraft parts, ST Engineering has been working on several key processes in a bid to lead the way in creating robust AM solutions for aircraft operations.
Defining Production Processes
For manufacturing methods that do not yet have industrial standards and specifications, a production process needs to be well defined first and foremost to provide assurance in safety and performance.
The promised performance must be reproducible consistently and reliably through a process qualification programme. This involves the tracing of many details, including all the customisable parameters, material specification and end-to-end handling details, machine and facility manning, digital file creation and control, quality assurance as well as minimum performance.
R&D engineers Zhang Yongjie and Yeoh Yong Chen play key roles in the development and definition of these processes at ST Engineering. Both Yongjie and Yong Chen are studying different AM areas for their PhD research under the Industry Postgraduate Programme with Nayang Technologies University in Singapore. In addition to following and capturing the latest standard and guideline developments in the course of their work, they also take references from the research frontier to shape the foundation of the Group’s AM processes.
To date, ST Engineering has developed a series of processes covering AM methods which have gained, or are in the process of getting approval from airworthiness authorities. What these breakthroughs will help further achieve is to facilitate the Group in developing AM solutions for the actual application. So far, two areas have been identified for AM application – cabin interior parts and customised parts.
Cabin Interior Spare Parts
Cabin interior parts were the first target area that ST Engineering identified for AM solution development, and there’s plenty of good reason to consider AM for spare parts. It is estimated that around 5-10% of the passenger interior is commonly found to be damaged, which provides a big opportunity for AM to deliver parts at the point of need. Just-in-time production of spare parts using AM helps avoid unnecessary disruption to the scheduled operations of the aircraft, especially when the parts require long procurement lead time.
While easing the stress on procurement may a key benefit in itself, ST Engineering has gone a step further by developing AM solutions with improved performance for cabin interior parts. Leonard Chai, Assistant Principal Engineer, is a lead designer from the Group who looks at design enhancement. One of the new design features he has introduced is a bracing panel to the armrest shroud of the passenger seat, which can be achieved by AM but not the traditional manufacturing method. This simple feature is able to yield 82% stress reduction in the current failure zone of the shroud, which in turn improves its durability.
A highly customised part with low quantity in demand can be expensive, while also requiring long lead-time to produce. There is however a sweet spot for AM application to be found where topology optimisation can be achieved in the design.
The Aerial Medical Equipment (AME) mount falls into this sweet spot when ST Engineering proposed the first-of-its-kind 3D-printed mount for use in securing and supporting medical equipment for operations on-board an aircraft. Through rounds of simulations performed in a virtual environment, with comprehensive reviews that included design, load and stress, printing and assembly process, engineering designer Damien Lim and Nguyen Hieu developed designs for AME mounts, which address not only the need for optimal Human Machine interface in the confined space of a cabin interior, but also with topology optimisation to facilitate AM application.
In using AM to produce a part such as an AME mount, Yongjie and Yong Chen had also considered the limits stemming from the physical dimensions of the 3D printer’s build chamber. A production strategy that addresses issues such as the directional effect of printing was developed as early as when the design is in the topology optimisation phase to integrate both design and production seamlessly.