Challenge

To identify, assess and mature innovative, flexible manufacturing methods of high-value aerospace products for determinate assembly.

Background

The University of Sheffield's Advanced Manufacturing Research Centre (AMRC) collaborated with BAE Systems, the project lead, and other consortium partners, which include Toolroom Technology Limited (TTL), the University of Nottingham (UoN) and Spirit Aerosystems. Together, they developed innovative manufacturing methods for measurement-assisted, determinate assembly (MADA). 

MADA integrates metrology, design, and manufacturing to achieve precise and efficient assembly of large-scale structures. The AMRC team validated these methods through a practical application, utilising a representative aircraft structure. 

AMRC engineers from the machining, composites and integrated manufacturing groups contributed to the project, which was grant funded by Innovate UK, alongside the consortium partners.  

The project was made up of three key research areas, which focused on:

• Adaptive, accurate machining undertaken by the AMRC’s subtractive machining and composites groups, alongside Toolroom Technology Limited.
• Robotic assembly and automated inspection, completed by the University of Nottingham. 
• Digital twinning using Unified Namespace (UNS), a growing approach which explores how to better architect an organisation's approach to information, researched by the AMRC’s integrated manufacturing group. 

The aim was to facilitate the machining of flexible parts independent of their counterparts to allow for efficient assembly at the University of Nottingham’s Omnifactory facility.

The project partners. 

Innovation

The AMRC’s machining team defined an adaptive machining process flow in collaboration with Toolroom Technology Limited and the University of Nottingham.  

This was successfully applied to the eleven parts from the BAE Systems representative aircraft structure.  

 AMRC engineers in the machining group achieved this application by: 

• On machine measurement of the true part position;
• Datum setting and compensation to account for true part position;
• Nominal hole drilling, including the install, post processor development and use of an automatic right angled head (RAH); 
• Definition of a coordinate measuring machine (CMM) inspection process for hole position measurement;
• Adaptive hole drilling and final part CMM inspection. 

Engineers in the AMRC’s composites team worked alongside BAE Systems and selected tool suppliers to develop dry drilling strategies for the machining of carbon fibre reinforced polymer/hysol/aluminium stacks. A design of experiments-based approach was used to identify appropriate cutting parameters for several cutting tool types. 

Following this, a statistical assessment of tool capability with respect to defined requirements at the identified cutting parameter sets was made. This allowed the most-promising cutting tool strategies to be identified for further development.

The AMRC’s integrated manufacturing team explored how best to utilise a Unified Namespace (UNS) - a single source of truth for all data and information communicated within a business - to create a digital thread as part of a future integration architecture to effectively collect, store, analyse and visualise data to enable insights to ultimately make informed decisions.

This work was based on extending the AMRC’s on-going Factory+ work, which has created a cutting-edge open-source reference framework that establishes the digital blueprints necessary for a state-of-the-art, connected manufacturing facility.  

The digital thread is the connection of integrated data sources about processes across the systems used throughout the entire lifecycle of the product, ensuring continuity and traceability. UNS supports this by providing a standardised approach to connecting and then accessing interoperable quality data.

In modern integration architectures, the concepts of digital thread and Unified Namespace (UNS) together will play a pivotal role in facilitating the seamless data capture, through to intelligent event-driven notifications when handling both vast volumes of high-frequency data and updates to larger files as demonstrated within this programme.

Result

The AMRC’s machining experts successfully drilled all parts from the BAE Systems aircraft structure  through a mixture of nominal and adaptive drilling, using the developed adaptive process flow. Unprecedented levels of positional accuracy were demonstrated to allow for fully automated and self supported robotic assembly of the sub assembly parts at the University of Nottingham with no manual fettling required. 

The composites team made significant steps towards the development of capable processes for the dry machining of CFRP/Hysol/Al stacks. Technological advances were also made in the understanding of chip load and tool temperature effects. 

Engineers in the integrated manufacturing team extended the modular architectural specification for a UNS to best articulate data requirements as a single machine tool would simply produce 5GB of data per day, per device, through a data acquisition (DAQ) deployed on the edge for just 14 data metrics systems at the required sampling rate of 500 Hz. 

A vast amount of data is unnecessary for wider business benefits, so by articulating what is needed for what use cases, both access to the data at an appropriate level, as well as any analysis and then aggregation can be done at the edge before being transferred over the integration architecture.

A key process within manufacturing is inspection, which creates a requirement to support ad-hoc transfers of larger files, common for metrology reports both on machine tools and dedicated measurement machines. The research explored how to achieve the benefits for both approaches in the context of our UNS implementation, Factory+.

Impact

The Flexcelle project has paved the way for an innovative manufacturing and assembly strategy for application on future aircraft programmes, requiring the assembly of flexible high-value aerostructural parts. 

In turn, the project has defined new requirements/standards for detail part manufacture in Europe in relation to determinate assembly and metrology assisted determinate assembly.

Through understanding the workflows, an information management approach can be established across the lifecycle, providing both real-time insights and historical analysis for ongoing procedures and as part of a product’s digital passport.

The stack machining work performed in this project has made a positive contribution to defining BAE Systems’ robotic stack drilling strategy, philosophies and machining parameters for future aircraft programmes. 

For further information, please contact Tom Finkill, innovation fellow, AMRC: 

E: t.finkill@amrc.co.uk

P: 07523 690053