Materials Testing in the Aerospace Industry

Aerospace is a demanding industry for new product development and quality control. AZoM talks for Dr. Mike Keeble from Buehler about how they are rising to the materials testing challenges set by the Aerospace Industry.

Please could you start by telling us about Buehler and what you provide to the aerospace industry?

Buehler is a division of Illinois Tool Works (ITW) - a global, Fortune 200 company and manufacturer of value-added consumables and specialty equipment with related service businesses. Buehler is the premier manufacturer of scientific equipment and supplies for the preparation of materials for microscopic analysis. We work in all industrial and research sectors globally, with offices in nine countries and distribution to more than 100 countries.

Buehler was founded in 1936 by a Swiss immigrant to the USA. Eighty-two years later Buehler is well established as the world’s leading supplier of materials preparation and analysis instruments, cutting edge hardness testing equipment, consumable supplies and application solutions.

The Aerospace industry is exceptionally demanding in both quality control and new product development. The industry requires the very highest standard of equipment and consumables, to ensure repeatability and reproducibility of results. In this way, the industry can ensure that the chances of critical failures are vanishingly small while maintaining efficiencies in both design and production.

Image Credits: Buehler

The aerospace industry relies on innovative materials to improve performance, weight and strength. What sets Buehler apart from other companies when testing these materials?

At Buehler, we have more than 80 years of experience that allows us to understand the critical factors in the metallographic preparation process, and ensure that these factors are well controlled. In addition, we have a network of applications specialists from a wide variety of backgrounds, who work together as a global team to solve some of the most challenging problems in materials preparation. With a mix of PhD materials scientists, experienced industry professionals, and a strong global network we can address any question that comes up. Buehler also partners with specialized research centres across the globe, where we are constantly keeping up to date with new technologies under development. We will often have established preparation and analysis techniques to support quality control needs before the technology ever gets to the open market.

What changes have you seen in the aerospace industry in terms of materials analysis and testing?

Of course, there is continuous development in the Aerospace industry, just as in many others. We’ve seen a shift from traditional metallic materials to more and more advanced metals, non-metallics and composite materials, as well as in joining techniques and manufacturing technologies. Some of these advances need extremely refined control of the material’s internal structure, which has pushed the requirements for materials preparation and analysis beyond what has previously been required. The driving force is for lighter, more powerful aircraft that optimise efficiency without sacrificing reliability. As we move towards the operational limits of the materials being used, effective quality control processes will become increasingly significant in allowing improvements in efficiency.

Image Credits: Oleksii Chumachenko/shutterstock.com

How has Buehler adapted to meet these changes?

Buehler has always retained a strong relationship with the research community, which has given us fantastic insight into new materials and processes as they’re developed. As complexities in Aerospace materials have increased, it has become difficult for individual companies to maintain the knowledge and experience in-house to analyse the range of materials that are being used. Our goal is to continue to have the most effective and reliable equipment available, with the most effective consumables, and to combine these with our knowledge of materials and industrial needs to create the most innovative solutions to problems. Being part of an organization such as ITW has allowed Buehler to make significant investment in R&D, introducing innovation as well as best in class reliability to our product range. Combined with our depth of understanding in key customer applications, we are able to design equipment and processes that addresses directly the needs of our customers.

Image Credits: Buehler

What materials do you typically test?

We can support the preparation and analysis of any material, and in Aerospace many are used! This includes nickel super-alloys, titanium, aluminium, fibre-reinforced polymers and a wide variety of composites. Very often, the greatest challenges in this area are when different types of materials are combined. For example, the preparation requirements for titanium and carbon fibre materials are very different – but manufacturers need to examine the interaction of titanium fasteners through carbon fibre panels. For applications like this, unique approaches are sometimes needed in order to get accurate measurements. Similarly, coatings on materials are particularly important in aerospace, and some of these coatings can be extremely difficult to prepare without creating artificial features that affect the measurement results. Materials preparation is a multi-stage process that requires each stage to be performed correctly to get good results. In these more complex scenarios, our experience and knowledge can be particularly helpful in supporting the needs of the industry.

Image Credits: Spacex/unsplash.com

Are there any materials or component materials where significant developments have taken place as a result of the materials testing solutions you provide?

The drive for development is often through the improved characterization techniques that continue to become available. In the past, the analysis of materials with optical and electron microscopes required preparation to be correct to a few microns. The rapid development and widespread use of advanced characterization techniques such as Electron Back-scatter Diffraction (EBSD) has led to the examination and development of much smaller features, in greater detail - and these require improvement in mechanical preparation. EBSD typically requires preparation to the nanometre level. This is achieved through maintaining a high level of quality through traditional mechanical preparation, and then using specialized equipment such as our VibroMet vibratory polishing machine.

Image Credits: Rossparmly/unsplash.com

Are there any recent case studies from the aerospace industry that you are particularly proud of?

We have provided individual solutions for a wide range of aerospace companies, driven by individual needs. These have included creating substantial improvements in efficiency for Aerospace fastener manufacturers, developing new techniques to examine microstructures of highly specialized components such as heat exchangers, examining new methods for analysing polymer matrix composites, and working with quality control laboratories on thermal spray characterization to improve both accuracy and reliability of results. Due to the nature of the industry, most of the details of these developments are confidential to the client – however, the principles we develop during these studies allow us to extend the effectiveness of our equipment and consumables to better support these needs.

The analysis of thermal spray coatings for aerospace applications has been an area of great difficulty in metallographic preparation for decades. Individual companies have established techniques for preparation that have given repeatability. However, the methods are extremely sensitive to change and the effect of mechanical preparation techniques can be critical. At present, this requires the industry to do extensive ‘round-robin’ testing and have operators that are trained to a high level.

I presented at the Thermal Spray Characterisation 2017, which was co-located with AeroMat, a paper on "Accurate Porosity Measurement in Thermal Spray Coatings Using ASTM E1920". I discussed individual factors in mechanical preparation of specimens, and examining the extent to which these factors affect the final measurements. Examples of real coatings and measurements were used to demonstrate the principles discussed. This along with other topics that speak to industry applications they can be accessed here.

Dr. Mike Keeble/Buehler - Porosity in Thermal Spray Coatings

Is Buehler exhibiting at AeroMat this year?

Yes, Buehler will be exhibiting at booth 1519 during AeroMat Conference – again co-located with ITSC. This year it is being held in Orlando, Florida May 7-9, 2018. We are excited to demonstrate our newest innovations for the aerospace industry. Buehler has developed a series of products to improve process efficiencies and quality of samples created for material testing. One of the products recently developed is ideal for sample sectioning. The IsoMet High Speed Precision Cutters are ideal for the low damage, delicate sectioning required in sample preparation for aerospace applications, yet are also capable of cutting through the toughest materials at speed when required. Materials preparation is a multi-stage process that requires each stage to be performed correctly to get good results.

Buehler will also be exhibiting at Control 2018, the International Trade Fair for Quality Assurance in Stuttgart, Germany April 24-27, 2018 Hall 5, booth 5135. The newest innovations for quality in both aerospace and automotive will be shown there.

High technology precision cutters such as the IsoMet High Speed use powerful motors and smart cut systems to manage delicate aerospace coatings as well as tough complex shaped fastener systems (Credits:Buehler)

What are your responsibilities as a Director of the International Metallographic Society and how do you hope it will help improve the industry as a whole?

The International Metallographic Society (IMS) will be celebrating its 51st anniversary this year. The society was created after it was recognized that the sharing and rigorous examination of proper metallographic techniques was vital to the effective development of advanced materials. The objective of the IMS is to advance the art and science of metallography and materials characterization by disseminating information via technical meetings, journals, and education courses. Buehler has a long relationship with the IMS, as well as the American Society for Metals (ASM International), and we work together to promote best practice, and to provide training and information to the Materials Science community. When I moved to the USA in December 2015, I was impressed by the dedication, knowledge and professionalism of this community, and became a Director in order to support the good work already in progress, and to help drive this world-class Society forwards with the incredibly rapid technological developments we continue to see.

How do you see materials testing moving forward in the aerospace industry over the next 10 years?

This is going to be an exciting time! Competition within the Aerospace industry is fierce, and there will be a continued drive for improved efficiency. This will, of course, involve development in core materials and processes, but it will also mean using them more efficiently. Technology change is swift, and the analysis techniques used will also continue to become more advanced. The inclusion of more and more composite materials will require a different approach to some quality control and through life analysis needs. In addition, greater control of manufacturing processes will push the capabilities of existing processes to greater heights. It will be an iterative cycle where improved characterization leads to further refinement in nano-scale properties of the materials, which then require improved analysis techniques to assess.

Image Credits: John Pearson/unsplash.com

Where can our readers learn more about Buehler and what you offer the aerospace industry?

The best starting point is often our web-site, www.buehler.com. Here you can find details about our applications experts, case studies, information on equipment and consumables, and local contact information.

About Dr Mike Keeble

Dr. Keeble graduated from the University of Wales, Swansea with an Honours degree in Materials Science and Engineering. He gained his Master’s degree in creep properties of steels and his PhD in mechanical testing and FE modelling of partially molten aluminium alloys.

Prior to joining Buehler, Mike worked as a research scientist in the Advanced Metallics division of the Defence Evaluation and Research Agency, now QinetiQ. His work ranged from fatigue, damage tolerance and failure analysis of aerospace materials to the development of novel manufacturing processes in powder metallurgy. At Buehler, Mike was originally based in the UK. He has more than a decade of experience providing support and training on advanced metallography and analysis techniques to all industry sectors. He concurrently held positions as Honorary Lecturer at Birmingham University and Visiting Academic within Warwick University and has served on ISO and ASTM committees for both mechanical testing and metallurgy. Mike relocated to Buehler’s headquarters in Lake Bluff, IL in December 2015 to take on the role of Laboratories and Technology Manager. Since this move, he has become an active member of IMS, TSS, ASM and ASTM.