Microlattice: how revolutionary metallic structures are benefiting global manufacturers

Dr Jacob M Hundley of HRL Laboratories in California, has recently been confirmed as the latest speaker at the Institution’s conference ‘A new dawn for metals’ taking place at the Boeing Advanced Manufacturing Research Centre in Rotherham on 14 March. Here, he gives us an insight into how microlattice materials and the world’s lightest metallic structure, which was developed by a research team at HRL, is helping to revolutionise manufacturing processes for global automotive and aerospace companies.

Dr Jacob M Hundley of HRL Laboratories in California, has recently been confirmed as the latest speaker at the Institution’s conference ‘A new dawn for metals’ taking place at the Boeing Advanced Manufacturing Research Centre in Rotherham on 14 March.  Here, he gives us an insight into how microlattice materials and the world’s lightest metallic structure, which was developed by a research team at HRL, is helping to revolutionise manufacturing processes for global automotive and aerospace companies.

HRL Laboratories in Malibu California, which is jointly owned by Boeing and General Motors, is recognised as one of the world’s premier physical science and engineering research laboratories.  Its scientists and engineers are at the forefront of cutting edge, pioneering research and development to provide real world technology solutions.

In 2011, HRL announced that a team of its researchers, led by Dr Tobias Schaedler, HRL’s principal investigator for the Science paper on ultralight metallic lattices, working in conjunction with scientists at several Californian universities, Caltech and the University of California, Irvine, had created the world’s lightest metallic structure, termed a microlattice.  The process to create the material, which is about 250 times lighter than Styrofoam, was first achieved at HRL in 2007, by Dr Alan Jacobsen.  Using his innovative fabrication process, the HRL team was able to make a material that consists of 99.99% open volume by designing the 0.01% solid at the nanometer, micron and millimeter scales, fabricating a lattice of interconnected tubes with a wall thickness of 100 nanometers, 1,000 times thinner than a human hair. 

The novel material offers revolutionary opportunities for manufacturing companies of all sizes across all industry sectors, and so it was natural for the Institution to invite Dr Jacob Hundley of HRL to share the insight, learning and experiences of the microlattice research team at its ‘A new dawn for metals’ event taking place on 14 March. 

Dr Hundley explained the genesis of how the material was developed: “My colleague, Dr William Carter, who is the manager of the Architected Materials Group at HRL puts microlattice materials in the context of large structures.  For instance, prior to the construction of the Eiffel Tower in the 19th century, the largest structure built by man was the Great Pyramid at Giza in Egypt.  Modern buildings, like the Eiffel Tower are incredibly light and weight efficient by virtue of their architectures.  The revolutionary concept from HRL is to bring the same principles down to the materials level by designing their architectures at the nano and micro scales.”

“In effect, it’s about architecting a material to make it the most efficient: putting material only where you need it.” 

“The design philosophy is to mimic what is done on the architectural scale using existing, commercially available materials.  This is the important thing for the automotive and aerospace industries:  there is no need to use exotic materials; for these sectors, you just want to take existing materials that the sectors are familiar with, but engineer and architect them so that they have new, innovative properties.”

Dr Hundley gives a fascinating insight into the drivers behind the development of microlattice materials for industry.  He said: “Microlattice materials are energy absorbing, efficient and very light; they are also formed through a rapid net-shape process, so they enable the replacement of materials or the elimination of processes within the manufacturing life cycle with associated high costs.  This is just an element of what microlattice materials can offer.”

“Perhaps its true benefit to industry is that here is a material that can be designed with an open cellular architecture which enables multiple functions, such as structural reinforcement and heat transfer, to be combined within the same component.  In this view, microlattice materials become an attractive proposition to manufacturers because they combine three desirable benefits: reducing costly manufacturing processes, multi-functionality and lightweighting.”

The researchers at HRL are also keen to point out that because lattice is a very efficient construct structurally, using microlattice materials offers revolutionary design freedom.  Dr Hundley said: “Microlattice materials enable us to decouple a lot of the stiffness and density constraints associated with conventional materials.  Consider the usual design process: you have a material which has a particular property, which you design around.  Your part is now going to take on a certain shape, as a result.”

“Our global philosophy is that we would like to change that.  If you have a function that you want to accomplish, you should be able to design a material to achieve that function.  So, for example, if I need an airplane component and it needs to look and perform in a certain way, how can the material be designed to meet those requirements?  This is the freedom that microlattice materials offer.”

The experience of the researchers at HRL in working closely with global manufacturers offers real insight for UK research engineers looking to help companies innovate or develop new materials or adapt existing products.  Dr Hundley explained: “Our scientists and engineers in the labs here at HRL could take a sample of a microlattice material, to a manufacturer and say: ‘Here is a new material for you,’ and then offer an example of a situation where it could be used.”

“However, the manufacturing company comes straight back and asks the form factor in which the material can be made, whether the research team can make it in quantities that the company actually needs, what the repeatability of the material is, and how its properties and performance can be tested through simulation.  These are the upfront needs and requirements of large scale manufacturers.”

“It’s not enough for researchers simply to create or develop a new material.  From our experience, we now know that new materials have to be part of a package which also includes simulation tools, and a manufacturing facility – too often these latter essentials are considered as an after thought, but at HRL, we have learned that everything has to be done concurrently.”

“Put yourself in the position of a global manufacturer in a very competitive market sector like automotive or aerospace.  Companies want to know that a material can be ‘mass-manufacturable’ and simulation tools are needed because the performance of the material needs to be tested and proved.  Automotive manufacturers, for example, simply do not crash test hundreds of cars any more – testing is limited and backed by extensive simulation.”

“Simulation is also important because we are not using exotic materials – just existing materials which have been re-engineered and architected in a different way, so their performance and properties can be tailored to a specific application.  If an automotive company cannot predict a material’s performance, there is no way they would put that material in a car – even if it is five times lighter or twice as thin as an alternative.”

The public perception is that microlattice materials are  perhaps most closely associated with the aerospace and automotive industries, but as Dr Hundley points out: “Any industry sector that has a requirement for lightweight multi-functional structures could be using microlattice materials.  It is an incredibly low cost, rapid production process.  The growth of the polymer template takes just 30-60 seconds, and watching it before your eyes is pretty cool! Of course, the time to convert to a metallic structure depends on the truss geometry/thickness and the type of material that is being converted.  Usually that is much longer than the time associated with forming the polymer structure.”

“HRL is equally owned by General Motors and Boeing, and both companies want lightweight multi-functional structures which absorb energy or transfer loads efficiently, but in terms of costs, loads and throughput scales, both organisations are at different ends of the spectrum.  This has been a real benefit to the research team here, because we have been able to observe, analyse and experience the full gamut of applications.  Microlattice materials are a good fit for automotive and aerospace, but it is also useful in areas such as recreational equipment and chemical processing.”

Summing up what HRL could offer the global manufacturing sector, Dr Hundley said: “In the long term our vision here at HRL is to revolutionize lightweight materials by establishing a cost-efficient, scalable process to design and manufacture microlattice materials with properties tailored for specific applications.”

To hear Dr Hundley speak about developing microlattice, book your place at ‘A new dawn for metals’ on 14 March: www.imeche.org/events/s1754

Images: Copyright 2013 HRL LABORATORIES – Photo: Dan Little Photography. 

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