In-process measurement improves quality, reliability of aerospace bearings

By developing in-process, non-contact measurement systems for aerospace bearings, significant benefits can be achieved in terms of both sample manufacturing for rapid programme development, and in the continuous production of bearings, says Nick Dowding

Driven by the demand to optimise aircraft performance, decrease operating and maintenance costs and reduce gas emissions, the aircraft industry is pushing towards the concept of more electric aircraft (MEA) and, ultimately, an all-electric aircraft.

The MEA concept provides for the utilisation of electric power for all non-propulsive systems.

Traditionally, these non-propulsive systems are driven by a combination of different secondary power sources such as hydraulic, pneumatic, mechanical and electrical.



However, recent technological advances in the field of power electronics, fault-tolerant architecture, electro-hydrostatic actuators, flight control systems, high-density electric motors, power generation and conversion systems, have ushered in the era of MEA.

This trend is accelerating, as aircraft OEMs collaborate with their suppliers to design new systems and implement new electrical-intensive architectures.

Barden products are high precision rolling bearings and integrated bearing assemblies for complex or critical applications such as aerospace, defence, medical and high performance vacuum pumps.

The bearings have to withstand harsh conditions, including extreme temperatures, demanding load profiles and high speeds, which often means they are custom engineered for specific applications.

By making use of advanced technologies and innovative solutions, Schaeffler is able to enhance the performance of customers’ products.

Barden UK is currently involved in a Research & Technology project, MEGCAP (More Electric Generation, Controls & Aircraft Power).

This three-year collaborative project is a UK Government-funded, multi-million pound aerospace research programme that officially began on 1st May 2017.

The lead partner on the project, Safran Electrical & Power UK, designs and produces electrical systems for aircraft, spearheading Safran Group’s strategic contribution to the development of “More Electric Aircraft”.

Barden is one of the supply chain technology partners on MEGCAP and is a key supplier of high precision bearings for use on Safran power generators.

The economic importance of MEGCAP is to pull in all elements of a UK-centric, vertically integrated supply chain and to invest in and develop distinctive, globally competitive technologies within that supply chain.

This involves the development of low cost, high performance electrical equipment, starter generator machines and electronic controls for future civil aircraft. MEGCAP will invest in upstream R&T, establishing UK-centric supply chain clusters.

As part of MEGCAP, Barden UK has received matched funding of £500,000 to develop new technologies for inline (in-process) measurement of bearing defects and quality, as well as developing the capability to perform adaptive machining.

The objectives are to improve the lead-time, reliability and performance of aerospace bearings.

Although the Schaeffler production plant for Barden bearings in Plymouth already uses offline, laboratory-based measurement technologies for identifying bearing defects and other quality issues, the aim is to industrialise these measurement technologies by taking them into the harsher realities of the production environment at Plymouth.

Initially, the project will focus on the development of non-contact, in-process measurement systems specifically after track-grinding and honing process for bearings, which will lead to significant benefits for both sample manufacturing for rapid programme (prototype) development and in continuous production of aerospace bearings.

This will focus on the development of non-contact measurement methods that will characterise the bearing surface (surface finish, roundness, etc) to ensure that any parts with raceway defects are eliminated before the bearing rings progress further through the process.

This could lead to adaptive machining being developed, which would allow the input forms as measured to adapt the subsequent machining process.

Using closed-loop feedback systems, measurement data from these in-process measurement systems can be fed back to production and machine tool control systems, which in turn could automatically adjust the track grinding and honing processes to ensure that only the best, defect-free rings progress through the process.

These technologies do not currently exist for use in this way and will need to be developed in conjunction with leading suppliers of non-contact measurement systems.

Benefits of in-process measurement

The ability to identify minor (sub-micron) defects immediately after track-grinding or honing process would ensure that only the best quality rings are passed forward for assembly.

This in turn will ensure that the product supplied to Safran will be of the best possible quality and more importantly will best reflect the design models used to predict in-service performance of bearings.

This will enable aerospace customers to develop prototypes more rapidly with higher confidence.

For standard production bearings and parts, this will ensure that a more predictable yield and a higher throughput are achieved, reducing lead times and improving on-time delivery.

Nick Dowding is Sales & Marketing Manager of Schaeffler subsidiary, The Barden Corporation (UK) Ltd.