With traditional composite tooling manufacture acknowledged as being an extremely lengthy and costly process, Tim Schniepp, senior director of composite solutions at Stratasys, looks at why the use of additive manufacturing offers a more favourable alternative.
Believe it or not, there was a time not that long ago, when the production of composite tooling was a very costly, laborious and fairly wasteful process. I’m talking about the time when manufacturers of composite structures, OEMs, and tooling suppliers had little alternative than to contend with traditional approaches and their many associated constraints. A time when manufacturers had to use traditional materials such as aluminium, steel, invar or expensive fibre reinforced polymer (FRP) tooling that meant long lead-times of several weeks or – in the case of larger, more complex tools – many months.
In those days, this led to costs often skyrocketing well into the tens of thousands of dollars, even for relatively simple tool geometries. This hardship ultimately impacted the timeline of entire development programmes and prevented both design optimisation and product innovation, and the resulting tools were heavy and difficult to handle and store.
I know what you’re thinking – the stuff of nightmares. Of course, as you’ll no doubt be aware, for many companies, this is still reality and partly explains why aircraft costs remain high and why composite parts can be so expensive.
In the case of an aircraft manufacturer and depending on the programme, a handful of composite parts might be all that are required, as there aren’t necessarily that many parts needed. For example, there are only a couple of hundred F-22 fighter aircraft in the world, yet the investment in tooling – both in terms of time and finances – for the manufacturer or OEM, is incredibly significant to produce what amounts to a relatively modest number of parts.
Not only that, these tools then must be stored for years should replacement parts be eventually needed. We’ve come across one company that keeps its tools in an unused car park behind its manufacturing facility, because they have nowhere else to store such big, bulky items. In a worst-case scenario, companies could spend over a year and hundreds of thousands of dollars for a very large, complex mould or mandrel that they might only use a handful of times.
And let’s not forget what happens if the design specifications for such tooling is found to be inaccurate or requires changes. Having worked on the design and production of cowlings (nacelles) for aircraft jet engines for one of the world’s leading manufacturers, I’ve experienced programs where the tool design was locked in as long as 12-14 months in advance. In the event of a significant design change, the impact can be quite dramatic, requiring costly, time-consuming modifications to the tool, and potentially causing major delays to the delivery of structures and thus the manufacture of aircraft.
3D printing for composite tooling
The good news is that it doesn’t have to be this way. Indeed, for an increasing number of forward-thinking savvy manufacturers, it isn’t.
The advanced composites industry has shown continual need for innovative tooling solutions and one fast emerging technology is unquestionably 3D printing (additive manufacturing). Some OEMs and leading tier suppliers in the aerospace industry have been utilising 3D printing for the rapid production of cost-effective composite tooling for many years. However, while there are a variety of additive manufacturing technologies, the important and most relevant focus is on extrusion-based technologies.
One such solution is Fused Deposition Modelling (FDM) 3D printing technology, which builds parts layer-by-layer by heating and extruding thermoplastic materials in a highly controlled and automated manner. FDM allows the rapid production of highly-effective composite mould tooling across a broad range of tool sizes and complexities, which are capable of performing at cure temperatures in excess of 180 °C in typical autoclave cycles (consolidation pressures exceeding 0.7 MPa).
Boeing actually revealed its use of FDM technology for composite tooling in 2012 as part of a SAMPE (Society for the Advancement of Materials and Process Engineering) technical paper describing its development effort for large, complex, out-of-autoclave co-cured structure.
In order to meet the demands of composite tooling applications, we’ve worked to enhance Stratasys’ 3D printing capabilities and material properties, namely temperature resistance, enhancing the offering of 3D printed composite tooling.
Material advances taken to new heights
Stratasys invested substantially in providing 3D printing solutions tailored to the unique needs of the composite tooling requirements. The Stratasys introduction of the high-temperature thermoplastic ULTEM 1010 resin, combined with a 2X+ improvement in throughput provided by the Stratasys F900 Acceleration Kit is allowing customers of FDM 3D printing technology to significantly disrupt the composite tooling supply chain. And it is an area of continued investment as well, as new capabilities and high performance, production-tooling oriented materials that are intended for near-term market impact are currently in development.
Stratasys’ development of high-temperature materials, as well as the increased throughput of its production 3D printers, enable the manufacture of high-temperature lay-up tooling in hours or days, rather than the weeks or months it would take to produce and procure tooling made from traditional approaches. Moreover, 3D printed tooling can offer disruptive cost-savings compared to traditional tooling materials and numerous other less quantified benefits, such as dramatic weight savings. Case studies with OEMs like Dassault Falcon Jet, Aurora Flight Sciences, and SSL (formerly Space Systems Loral) illustrate the potential for over 80% reductions in cost and lead-time.
Another recent example that demonstrates the significant time-saving by this process is with Formula 1 racing team and Stratasys customer, McLaren-Honda, which used FDM 3D printing to produce a new race-car wing in under two weeks during the 2017 Grand Prix season. In this instance, the team 3D printed an ULTEM1010 mould tool to create the shape of the wing. Since this material can withstand the high temperatures involved with curing composite structures, it was used throughout the cure cycle to produce the final structure. The carbon fibre composite wing was then removed from the tool leaving the team with a reusable composite layup tool.
The additive nature of 3D printing that results in material only being placed where it is needed, also means that great efficiency and minimal waste are a natural result of the process. This not only significantly reduces material usage, but also cuts the weight of tooling dramatically. This optimisation allows for tooling to be handled by human operators rather than cranes or lifting devices and also reduces the thermal mass of the tool during the curing process. This further decreases recurring costs and operational inefficiencies.
So, in summary, it’s all about enabling manufacturers to get products to market faster and via reduced investment costs. The opportunity to enjoy such benefits and improve business performance offers great value to which manufacturers should definitely give strong consideration. As the demand for new applications, product improvements and faster, lower-cost tool creation continues to build, composite part manufacturers are forced to innovate to remain competitive, especially as the early adopters of this technology are already reaping the benefits that 3D printed tooling offers.