QMT Features: March 2013
Innovation works at EADS
EADS Innovation Works has used 3D imaging/reverse engineering software, together with 3D printing technology,  to meet the needs for  precise mechanical parts replacement for military vehicles and equipment in the field.

Although modern military hardware bristles with advanced technology that gives it capabilities that seem, to the general public at least, to verge on the impossible, it takes several years for the latest technology to be put into regular service. As a result, the fact is that a large proportion of the aircraft and military vehicles – from tanks to trucks – that are in use today by armed forces around the world can be anything up to 20 or 30 years old – or 60 in the case of the B-52 bomber.

That presents a major logistical challenge when these aircraft and vehicles are deployed to conflict areas, especially if those conflict areas are on the other side of the world. When vehicle breakdowns occur, during a conflict or in peacetime, replacement parts must be available where they are needed, without delay. That means either that appropriate spares must be stored where the vehicles are deployed so that they are readily available should they be needed, or they must be flown out as and when required.

That logistical requirement is complex and costly enough on its own. On top of that is the fact that, because of the age of many of the vehicles still in daily use by armed forces, the procurement or supply of spare parts for these ageing vehicles and equipment is becoming more difficult as time goes by. So in many cases, replacement mechanical parts have to be made from scratch, either on demand or for storage for possible future use. Even with today’s 3D CAD software and CNC machining technologies, this again adds to the complexity and cost of replacement parts provision.

However, EADS Innovation Works has come up with a possible solution to this growing logistical problem. It involves the use of a FARO ScanArm 3D laser scanner, Geomagic Studio 3D imaging/reverse engineering software and an Arcam A2 EBM (electron beam melting) additive layer manufacturing (ALM) direct manufacturing system.

Advanced research and technology
EADS Innovation Works comprises a global network of Technical Capability Centres and serves all of the business units of EADS (European Aeronautic, Defence and Space company). These business units are passenger, freight, military and corporate aircraft maker, Airbus; military and civil helicopter manufacturer, Eurocopter; space transport and satellite systems developer, Astrium; and defence and security systems specialist, Cassidian.

Operating the EADS corporate Research & Technology (R&T) laboratories around the world, the mission of EADS Innovation Works is to identify new value-creating technologies and to develop technological skills and resources that can be of benefit to any or all of these EADS business units – or indeed, to organisations outside the EADS community.

The project to develop a quicker, more cost-effective way to provide the required replacement parts for aircraft and military vehicles is one example of the type of work undertaken by Innovation Works. Jon Meyer, research team leader in the Metallic Technologies & Surface Engineering group at EADS Innovation Works’ facility at Filton, near Bristol, UK, outlines the aim of the project.

“This was a proof-of-concept project,” he explains. “The whole idea behind it was to demonstrate that additive layer manufacturing technology could cut the time and the cost involved in providing replacement parts for ageing aircraft and vehicles. Instead of needing to store parts locally or have them flown out, the failed original part could be scanned, digitally modelled and then produced, on demand, at the same location as the vehicle for which it is required. In practice, each location would be equipped with a 3D scanner, the necessary software and an additive layer manufacturing machine.”

Three-step process
The item selected by the project team for use as an example was a brake calliper from a car – for no other reason, really, than that it was available.
The first step in the process was to scan the calliper with the FARO ScanArm laser scanner. This can record data at a rate of nearly 20,000 points per second to an accuracy of 0.035 mm. The individual scans required to capture the whole calliper were saved as a series of point cloud files that were then read into Geomagic Studio 3D imaging/reverse engineering software.

The second and crucial step in the process was to then use the tools in Geomagic Studio to convert this ‘dumb’ point cloud data into a watertight 3D digital polygon surface model that accurately replicated the shape of the original calliper and that could be used in the final manufacturing process.

As the calliper comprised a combination of complex and simple shapes and required several separate scans to capture it fully, once the individual scans had been registered with each other and combined to produce a single point cloud model of the calliper, the resulting file contained several tens of millions of 3D coordinate points. The software’s ‘curvature sampling’ tool was therefore used to reduce the points count in flat or low curvature areas while retaining it where there was high curvature. This reduced the overall file size to a more manageable size without losing any of the detail. This would speed up subsequent processing. The data was also ‘cleaned’ to remove any scanner noise and ‘outliers’ that had been picked up during the scanning process.

The software also enabled the team to fill in areas that the scanner couldn’t capture fully, such as holes for fixing bolts, which extend from one surface, through the calliper to the opposite surface. The scanner was only able to capture their location and circumference - not their full depth. So with Geomagic Studio, the team first created a model of the entire calliper without the holes, then used the software’s tools to clean and sharpen the surface edges of the holes as captured by the scanner. These were then ‘pushed’ through the model from one side to the other to create the bolt holes.

Other tools in the software enabled them to smooth areas of the model and to refine it using digital ‘sandpaper’.

3D printing
Once the 3D polygon mesh surface model was complete it was saved as an STL (stereolithography) file and exported to the Magics additive manufacturing and rapid prototyping build preparation software from Materialise for the third and final step. After the data had been ‘conditioned’ here, the production of a replica calliper in titanium could begin on the Arcam A2 EBM additive layer manufacturing system.
As with all additive layer manufacturing techniques, the EBM process requires that, first, the 3D digital model of the part that is going to be manufactured be digitally ‘sliced’ into cross sections, each as thin as 0.1mm, or less. The data representing these cross sections then controls the EBM machine’s movements to form individual layers that are built up, layer by layer, from metal powder melted by a powerful electron beam to create the physical part.

Each layer is melted to the exact geometry defined by the 3D digital model of the part. For each layer of powder, the electron beam first scans the powder bed to maintain the required temperature for the alloy being used. It then melts the contours of the part and finally the bulk. Parts are built in a vacuum at high temperature, which results in stress-relieved parts with material properties better than cast and comparable to wrought material.

Realising the benefits
While the replica calliper produced on the EBM system was geometrically accurate, in practice parts produced using this process would also need to meet international standards and certification requirements. This is especially so in the case of aircraft parts, where meeting internationally agreed certification requirements is essential before parts can be put into use.

In the case of land-going vehicles, however, the process as demonstrated by EADS Innovation Works already has the potential to bring real benefits in terms of providing spare parts in a timely, cost-efficient manner.

The process also brings a number of more general benefits. For example, ALM technology is more resources efficient – and therefore less costly and more environmentally friendly - than traditional machining in terms of material usage because it doesn’t start with a billet of expensive material, most of which is then machined away to produce the part. ALM uses only the amount of material required to make the part, irrespective of its complexity.

Further, parts can be produced with ALM technology on an as-needed basis, where they are needed, so there is the potential for reduced parts storage and transport costs and reduced delays in delivery.

There’s also a benefit from the user’s perspective, because it can remove one of the steps required in the more traditional process. There’s no need for a CAD model. It’s just 3D scan, to 3D digital model, to 3D printed part.
The process demonstrated by EADS Innovation Works shows clearly that the combination of 3D scanning, Geomagic Studio 3D imaging/reverse engineering software and additive layer manufacturing technology has the potential to cut the time and cost involved in providing replacement mechanical parts for ageing aircraft and military vehicles on deployment – or indeed, for any type of equipment in any situation when parts are needed now but are hard to source. l
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