Topology Optimization and Direct Metal 3D Printing (DMP) in GE Aircraft Engine Bracket Challenge

Product: DMP Printing
Industry: Aerospace and Defense 

Frustum Inc. software and 3D Systems’ Direct Metal Printing expertise cut aircraft bracket weight 70% while meeting all functional requirements.

The conundrum of balancing the design of a part with the constraints of manufacturing has existed since the Industrial Revolution. Conventional manufacturing techniques have limited capabilities to realize complex geometries or organically shaped components on a cost effective way. This results often in components where functionality and performance are a trade-off.

Now that 3D printing, especially Direct Metal Printing (DMP), has become a viable manufacturing alternative, the constraints imposed by traditional manufacturing have been very much removed. In response to this, software tools for Multi-Disciplinary Design Optimization are now emerging to deliver a convergence point. Topology optimization software is now capable of generating the most efficient designs for one-step manufacturing on the latest generation of DMP systems. Translation? What you model is what you manufacture.

This confluence of technologies was demonstrated recently in a project undertaken by software company Frustum and 3D Systems’ On-Demand Parts service, Quickparts. The project was a publicized challenge by GE Aircraft to reduce the weight of an aircraft bracket while maintaining the strength needed to meet all of its functional requirements, primarily supporting the weight of the cowling while the engine is in service.

The critical nature of weight

Since the beginning of motorized travel on land, air or sea, engineers have striven to balance the demands of weight vs. strength. The balancing act has become more critical in recent years with greater worldwide manufacturing competition, stricter energy conservation measures, escalating cost and delivery time pressures.

Weight is especially crucial for modern aircraft. Although a Boeing 737 weighs approximately 65 metric tons, eliminating only one pound in weight can generate savings of hundreds of thousands of dollars each year for airline companies. Spread that number out to include all aircraft worldwide and the savings are upwards of $10 million according to a GE Aircraft white paper.

Optimizing the design

For the GE Aircraft challenge, Frustum’s software for topology optimization provided the first steps in tackling critical weight vs. strength issues.

Topology optimization determines the most-efficient material layout to meet the exact performance requirements of a part. It takes into consideration the given space allowed, load conditions of the part and maximum stresses allowed in the material.

Frustum’s software automatically generates optimized geometries from existing CAD files. It creates material between the design features to make optimally stiff and lightweight structures. Smooth and blended surfaces reduce weight and minimize stress concentrations.

“Based on an existing conventional part design, our software automatically produces optimized geometry for Additive Manufacturing, without needing to do any remodeling,” says Jesse Blankenship, CEO of Frustum.

Unlike parts manufactured by traditional CNC or casting methods, the complexity of the model generated by topology optimization is of no concern, as DMP handles extremely complex models as easily as simplistic ones. Complexity comes at no cost.

Providing the 3D printing expertise

Once the initial design was generated, 3D Systems’ expertise came into play.

3D Systems’ On Demand Manufacturing service, Quickparts is the world’s leading provider of unique, custom-designed parts, offering instant online quoting, expertise in 3D design and printing, and proven manufacturing services support. This worldwide service is especially well-versed in the more complicated aspects of Direct Metal Printing.

“Direct Metal Printing is much more complex than plastics printing,” says Jonathan Cornelus, business development manager for 3D Systems Quickparts. “We help our customers to develop parts suitable for DMP, with minimized risks for part distortions or build crashes. We print components using optimized parameters based on our long-term experience in printing parts for customers.”

Manufacturing a better part

In the case of the GE aircraft bracket, Frustum’s software took the original CAD file and performed the topology optimization in one step, delivering an STL file.

3D Systems provided manufacturing advice on the process, material specifications, the best build orientation to deliver optimal part properties, achievable tolerances, and identified potential risk for deformations. The part was built on a 3D Systems ProX™ DMP 320 system.

The ProX DMP 320, introduced in early January 2016, offers several advantages for optimizing the weight vs. strength for the aircraft bracket.

Preset build parameters, developed by 3D Systems based on the outcome of nearly half-a-million builds, provide predictable and repeatable print quality for almost any geometry.

A totally new architecture simplifies set-up and delivers the versatility to produce all types of part geometries in titanium, stainless steel or nickel super alloy. Titanium was chosen for the GE aircraft bracket, based on its superior strength even when material is thinly applied to lower a part’s weight.

Exchangeable manufacturing modules for the ProX DMP 320 system reduce downtime when moving among different part materials, and a controlled vacuum build chamber ensures that every part is printed with proven material properties, density and chemical purity. The small portion of non-printed material can be completely recycled, saving money and providing environmental benefits.

An eye opener

The completed part, designed by Frustum and DMP-manufactured by 3D Systems, passed all the load condition requirements specified by the GE challenge and stayed within the same footprint while reducing weight by a staggering 70 percent.

“This is the kind of project that should be a real eye-opener for automotive and aerospace companies, where reducing weight while providing the same or improved functionality is the lifeblood of their design, engineering and manufacturing operations,” says Cornelus.

Beyond the design and performance of the part itself, Cornelus points out that topology optimization teamed with DMP can often consolidate multi-part assemblies into a stronger single part, eliminating fasteners and connectors that are often the cause of failures.

Finally, there is the coveted advantage of speed. Production-grade parts in tough materials such as stainless steel, titanium and nickel super alloy can be turned around by 3D Systems in as little as two weeks to satisfy the ever-quickening pace in myriad industries.

NuVasive Taps AM Ecosystem to Optimize Spine Implant Technology

Product: DMP Print
Industry: Medical

NuVasive saw an opportunity with additive manufacturing (AM) back in 2015. The orthopedic device company recognized that the unique capability of AM to produce complex and optimized shapes could open new avenues in its design and manufacturing of minimally invasive, procedurally integrated spine solutions. The only snag was that no one at the company possessed AM experience.

NuVasive knew that it needed to partner with a service and manufacturing provider for the AM process. The result of that ultimate collaboration was that NuVasive quickly capitalized on the advantages of AM, going from design to market in just over one year with the 2017 launch of Modulus®—now a full implant line.

Picking a partner to grow expertise

Optimized spinal implant by NuVasive produced using 3D printing

Even accounting for the talent and expertise housed within the NuVasive team, hard work combined with strategic innovation allowed the company to successfully design, qualify and bring to market an optimized family of AM implants in 14 months. If this were a subtractively manufactured product, this would be no surprise: NuVasive has a 180,000 square-foot manufacturing facility in West Carrollton, Ohio, where it performs traditional manufacturing day-in and day-out. AM is another story, and the novelty of the approach to the company and its workforce presented unique challenges.

Realizing that they needed outside counsel, NuVasive first identified several topline criteria for selecting its AM expert. The quality and reliability of the available 3D printing technology were both non-negotiable. The company needed software application support to effectively manufacture a novel device. Lastly, it sought a partner that had credibility within the AM industry and could grow alongside NuVasive.

“We were not willing to take any risks in this regard,” said Jeremy Malik, Director of Product Development at NuVasive.

After conducting thorough research, NuVasive chose 3D Systems, with its Direct Metal Printing (DMP) technology and team of application engineers and AM experts, to commercialize Modulus.

Proceeding from concept to commercialization

The design philosophy behind the Modulus line was to utilize new technology in a meaningful way to deliver a final product that is innovative, as opposed to new. According to NuVasive, the company’s goal was to provide the optimal spinal implant without making significant tradeoffs in the process.

3D Systems' metal additive manufacturing machines at the Customer Innovation Center in Denver, CO

The Modulus line balances porosity with load sharing, and each independent SKU is optimized for improved radiolucency. This was achieved through topological optimization, an algorithm-based design strategy that removes excess material that serves no structural or functional purpose. A component that has been topologically optimized is lighter-weight with no adverse impact on strength. In the case of the Modulus line, topological optimization also facilitates better imaging characteristics across all shapes and sizes of implants, giving surgeons a better view into bone fusion during follow-up. In addition, the optimized lattice structure provides a fully porous architecture that creates an environment conducive for bone in-growth.

“We wanted to do things we couldn’t do before,” Malik said. “There is more to this device than simply utilizing a new technology to bring it to market; we used new technology to help drive improved clinical outcomes for patients.” 

Together, the two companies generated a number of file iterations for different ways that the desired devices could be printed, and 3D Systems provided critical industry expertise on print strategies, metallurgy and residual powder removal, among other unfamiliar but impactful AM aspects.

“We didn’t know what we didn’t know,” Malik said. “3D Systems helped educate us on the additive process and worked with us to iron out our process beyond just the printing. We had a lot of open dialogue, and that communication was key to our success.”

Through the process, NuVasive leveraged 3D Systems’ Customer Innovation Centers (CICs). These facilities, and access to the expertise housed within them, provide an ecosystem of AM solutions that include design and manufacturing capabilities, along with premium hardware, software and materials. Covering everything from application development and frontend engineering, to equipment validation, process validation, part qualification and production, 3D Systems’ CICs help companies with various experience levels accelerate innovation through additive technology.

From design to production, NuVasive was able to capitalize on what the technology had to offer in terms of improved functionality without making large initial investments.

The two companies also collaborated beyond design optimization to achieve a qualified AM production workflow. Notwithstanding NuVasive’s track record in earning FDA clearance on products made with traditional manufacturing, using a new process introduced unique regulatory challenges.

According to Malik, NuVasive addressed those issues by leveraging 3D Systems’ data on manufacturing reproducibility in order to bolster its justifications in its FDA submission.

“3D Systems had customers who cleared devices through FDA in the past, so we knew we partnered with someone who had in-house expertise to help us navigate these requirements,” he said. “That was a nice safety net.”

Integrating additive into the portfolio

Fast forward to today, NuVasive is a spine leader in AM with a fully 3D-printed family of FDA-cleared spine implants on the market. The Modulus line is the result of thoughtful design, and balances the benefits of porosity and performance requirements of interbody fusion devices.

In the end, it took NuVasive roughly 14 months to go from concept to commercialization with its Modulus product line. Although this is a fairly standard timeline for traditional manufacturing processes, the company was excited that it was able to maintain the same pacing in its first application of AM.

“It is a significant undertaking to build your production process in addition to designing and building your product,” Malik said. “We were proud we had the ability to develop both, and relied on 3D Systems to help build out our datasets and justifications in order to get us to market.”

As to product manufacturing and deployment, 3D Systems provides supply chain flexibility and fulfills volume production orders internally or through certified partners, as well as helps customers transition to additive production at their own facilities through knowledge and technology transfer.

NuVasive is beginning to do its own titanium 3D printing in-house, and is using DMP technology for R&D prototyping, as well as to better understand how the machines work to continue refining its production process.

“It’s been a huge improvement for us to have that capability on site,” Malik said. “Now we have a legitimate, scalable manufacturing process and the ability for continuous improvement in the future.”