Final Report Summary - NOGAP (Development of a rapid, multifunction, automated gap filler device)
Executive Summary:
However, the stringent NLF surface requirements are difficult to be reached with conventional manufacturing processes. NOGAP project has developed a fully automated gap filler device that is able to performance in a 3D environment and achieve surface finish within NLF tolerances at high production rates.
To achieve its purpose, NOGAP project has integrated different systems in a single multifunction robot:
• Computer Vision system and 2D laser measurement device integrated in a verification system, for guidance, surface scanning and post-application metrology control.
• Innovative filler injection system with flow software control and variable-geometry nozzles (under patent development).
It can be said that NOGAP project has developed the first automated gap filler device for aircraft manufacturing that is accurate enough to maintain the surface quality to NLF tolerances. Technological leaps achieved in the NOGAP device are:
• Fully automated and easy to use gap filler device.
• Multi-task device, as all filling stages (gap analysis, sealant mixing, curing, post application metrology and curing) are performed by one single robot.
• No direct manipulation of the sealant by the operators, avoiding high number of errors and reducing the time for application.
• Surface finish requirements verified by computer vision and laser sensors.
• Flexible gap filler device that can be used to fill other joints (i.e. chord wise joints, countersinks or minor service defects), in contrast to actual specific tooling developed to specific aeroestructures of a specific aircraft programme.
• High production rate in contrast to high application and rework time of actual devices.
NOGAP project has made a significant contribution to the flexibility and automation of assembly tooling, which is a step forward to achieve the Aeronautical Factories of the Future based on the concept of “Smart Factory”.
Project Context and Objectives:
Current sealant materials consist of two components, base and curing agent, which reacts at room temperature. Base material is based upon standar polysulphide sealan technology, whereas curing agents are oxygen donors which react with thiol groups and which start the process of crosslinking by polycondensation.
This sealant is also used in automotive and building industry, even though aeronautics is the principal market due to its chemical resistance to fuel. Formulation is adjusted according to the specific application and the properties sought.
SEALANT SUPPLY
The two components of the aeronautical sealants are supplied in two possible configurations:
a. Two-component Kit (packed in a wide variety of weights), which are mixed together according to a relation specified by the supplier. The mixture of the two components could be performed manual or semi-automatic.
• Manual Mixing (KIT).
In this case the mixture is carried out by the operator by manual mixing adding the hardener base in suitable proportions.
• Semi-automatic Mode: Mixing machine (KIT)
This procedure is typically used for cord sealants but it may also be used for seam fillers. The equipment used for mechanical mixing of this type of sealant is planetary and can be equipped with a cooling system to prevent mixture heating.
Once the mixture is ready, it is packed in cartridges similar to Semkits by extruding the mixture with a press. These packages are then frozen at -70ºC and stored at -60ªC until use.
This technique implies a significant consumption of time and resources as well as an inherent risk of handling errors introduced by operators.
b. SemKit or individual two-chamber package, which contains precise weights of both components (typically 130 g), which are mixed by hand or with a specific pneumatic equipment. SemKits are packages prepared by the manufacturer with the exact amounts of base and catalyst compounds but without being mixed. The mixture is performed by rotation of a plunger which enters the base into the catalyst. The rotation of the plunger can be done manually (in accordance with the number of strokes that have been defined by the manufacturer) or with a SemKit automatic mixer as shown in the following figure.
A priori, the use of Semkit has certain advantages over the use of a two-component kit. However, their use is not widespread since the cost of the products in this type of package is considerably higher.
One of the advantages of using SemKits is that the manufacturer provides appropriate proportional amounts of base and catalyst. Therefore, potential weighing errors that may occur in the mixing of Kits are avoided. In addition, other stages are also avoided such as pressing packings for filling or sealant freezing and defrosting.
Recently, end-users have introduced a stage for pre-mixing and freezing the sealant before its application in aerostructures assembly processes. The process involves the feeding of the base and the curing agent to a mixing chamber, extruding the mixture to SemKit-type packages, freezing instantaneously and subsequent storage in freezing chambers.
Premixed and frozen sealants have the great advantage of removing the mixing process in assembly areas. Consequently, as a result of being applied once they are defrosted, as a single component, they save time in manufacturing. Additionally, the cleaning of the mixers which involves the use of organic solvents at the shop floor is avoided.
However, despite these advantages, worsening of some of the properties of these sealants has been detected (For example, reduction of the time for application, or application problems due to a nonhomogeneous defrost). These problems are having a negative impact on productivity, since it involves the demoulding of the sealant, further conditioning of the surfaces and reapplication of the filler.
POMPING AND METERING SYSTEMS
As detailed above, the current aircraft filler is a two-component sealant, so metering and pumping systems are particularly relevant for a correct application. Currently, guns for the application of bicomponent sealants where the metering and pumping are performed by manual operation are commonly used.
Aeronautical sealants are not the only two-component ones. In fact there are other bicomponent fillers, resins and chemicals that have already encountered the same difficulties that now arise in the aeronautical sector. Thus, other sectors are needed to be considered as baseline since there is no previous reference to automatic application of sealants in aeronautics. However, the particular characteristics of aeronautical sealants influence the process and therefore its application technology.
Bicomponent pumping and metering systems are normally composed of two independent tanks (one for each reagent) and a circuit consisting of filters, heat exchangers and metering pumps that provide the specific temperature and pressure to the sealant to achieve optimal conditions when reaching the mixhead. Moreover, a recirculation system from the mixhead is mostly included to avoid curing and therefore blockage.
Although these systems are versatile, they are primarily designed for dispensing rigid foam, cold-cured flexible foam, padding foam, integral skin foam or viscoelastic foams; and can be used with light sealants under specific circumstances.
Current technology is not optimized for sealants, and specifically does not apply to aeronautical ones. Their special features (density and viscosity) complicate the process and affect the design of pumps, heat exchangers, filters, recirculation system and mixhead. Thus, the high reliability demanded by aeronautics makes it completely discard this option.
These machines are designed for serial processes in which the bicomponent receiver element is moving, maintaining the gap filler device in place, and performing the same operation continuously. As a result, this concept does not take into account factors such as weight, compactness, transportability, flexibility of tools (mostly heads), ease of parameterization and ability to react to the parameterization.
These assumptions are precisely contrary to what happens in the aeronautical sector. Due to the size of the pieces, manufacturing tools move around them needing highly specific and particular machinery. Consequently, the concept of these devices is not valid for NOGAP project.
AUTOMATED GAP FILLER DEVICES
Robots are commonly used for the application of cords of sealant in the automotive industry, such as in sealing windows and windshields. This industry uses liquid and pasty sealant that is pumped to the robotic spray gun which regulates the flow of sealant to be applied.
The robot, along the programmed path, projects the sealant which solidifies upon contact with air. In this process, in addition to the accurate control of the robot path, it is extremely important to achieve a synchronized control of its speed and the sealant flow supplied by the gun since the amount of material projected depends on these two factors. Thus, gap filler devices are usually hung from the specific piece requiring continuous control of the robot path (position and speed accurately regulated) and including the regulation of the sealant flow provided in accordance with the robot speed.
Due to the specific characteristics and the high accuracy needed in aeronautics, automated gap filler devices are not known in this sector beyond laboratory tests and therefore, they are still under development.
The most advanced automated devices are used for the application of seam sealant in the automotive industry (Different viscosity from aeronautical one). These robots are installed on a rail and have the degrees of freedom needed for the application of sealant in the shortest time. This nozzle is normally located in a 3-axis Cartesian system or in a 6-axis robot.
Different companies supply robots that could be adapted to include a specific nozzle for the application of sealant in the automotive industry. There are different models that perform the task: Anchored to the ground; installed on a rail through which the device moves in a specific direction; installed on frames, so that the robot performs from the upper working area.
The software is the main core of the control unit and includes all the basic functions, such as, path planning, management of inputs and outputs, and additional functions as for example curing.
COMPUTER VISION
The strict requirements and the need of high accuracy of the aeronautical sector force the manufactures to develop new systems suitable for post-application metrology, such as computer vision. This technology could be used to verify tolerances, this is panel misalignment, gap geometry and filler tolerance. Nevertheless, the drawback of vision systems is their dependence of illumination and the differentiation of textures.
There are different approaches to control sealing depending on the type of material to be sealed or the filler itself. However, the usual trend is to use laser technology along with a camera in order to detect any divergence of the laser with respect to the expected curve. All these methods work with laser triangulation method. This method can be extended by dividing the laser beam into multiple lines to have several references in the same image. Thus, the effectiveness of the control will be increased, and in addition, the direction of filling could be defined to implement corrections.
Despite the degree of development for automotive applications, commercial gap filler devices do not meet aeronautics sealing requirements, and therefore the restrictive NLF tolerances:
• Sealant Composition: The device design depends entirely on the characteristics of the sealant and current aeronautical one has certain characteristics that differ from automotive sealant (two-component, viscosity, density). Moreover, it is know that current aeronautical filler material has shrinkage problems.
• Accuracy: Aerospace need to develop expensive specialised automated filling machines because standard industrial robots lack the accuracy required for NLF aircraft assembly.
• Manufacturing environment: Devices on the market are designed primarily for the automotive industry which uses a completely different manufacturing scheme. Automotive robots are also designed to perform a single task thousands of times, whereas the lower production rates and longer cycle times for aircraft demand robots that can perform more than one function.
• Software: Due to the accuracy required, it is necessary to develop specific software that included computer vision systems to follow patterns without losing the position.
OBJECTIVES
In light of the foregoing the objectives of NOGAP project were:
• Evaluate new filler materials (toughened epoxy fillers and UV curable sealants) that avoid mixing problems, improve surface finish, reduce shrinkage and enable automation, while ensuring good adhesion, flexibility, fluid resistance, temperature stability.
• Substitute current two-component fillers for new sealant materials and therefore, drastically change existing pumping systems and avoid the associated problems stated above. Moreover, integrate a smart nozzle able to adapt its geometry according to the need of filler detected by a sensor. Hence, the accuracy of NOGAP metering system is largely higher.
• Develop a multi-task automated seven-axis robot able to independently perform, detect and analyze gaps, apply specific amounts of sealant depending on the specific size of the gap, curing if necessary and verify surface finishing. The also incorporate software to be programed according to the surface finish tolerances demanded. Thus, NOGAP technology is flexible to fill any type of gap within standard or NLF tolerances.The combination of rapidity and accuracy will be the main constraints for NOGAP technology development.
• Develop a combination of computer vision and laser sensors in order to avoid illumination problems, the limitation to painted surfaces, define a virtual plane to control the height and the application of sealant at right angles, and to evaluate surface finish.
Project Results:
The main scientific and technical results achieved in each technical work package of the project are shown below:
WP1. Background study on filling techniques and devices
The purpose of this work package was to outline state of the arte technology for gap filling.
Background studies of commercial aerospace surface smoothing sealants were done with the aim of reporting and identifying all the potential design solutions for NLF aircraft wings manufacturing.
A range of sealant types was listed in order to fulfill the various applications, but polysulphide sealants are predominant. Polysulphides offer a balance of good application and cure characteristics from a manufacturing engineering perspective with good all-round performance in terms of physical properties and chemical resistance over a wide temperature range. However, they have limitations in performance terms which are their limited resistance to phosphate ester hydraulic fluid and their limited long-term oxidative stability. The most commonly used cure agents for polysulphides is manganese dioxide. However, epoxy agents for polythioether systems are also available .
Emerging drivers for the future development of surface smoothing aerospace sealant technologies, such as new polisulphide, and UV-cured sealants as well, are a key point for lower densities, lower shrinkage; improve surface finish helping to achieve Natural Laminar Flow aircraft wings surfaces and also to enable the surface smoothing process automation. Unfortunately, there is no further information reported due to the early stage of the developments.
Moreover, in order to help in the improvement of commercial sealants properties, it has been listed the most influent modifiers that allow a change in the sealants properties. These modifiers are adhesion additives, accelerators, fillers, solvents and adhesion promoters. Furthermore, it was explained the cure chemistry that sealants and the main chemical curing and adhesion mechanisms.
CT and FIDAMC have made a batch of test to determinate the properties of proposed sealant materials of 3 different suppliers (PPG, Chemetall and SIKA). Both commercial and innovative sealants are studied including current polysulphide sealant technology, toughened epoxy fillers and UV curable sealant.
In total 7 different products (different in properties or format) have been characterized, main characteristics are the following:
• Viscosity
• Degree of contraction from the fresh state to the cured state.
• Necessary force to apply in the pumping system.
Significant results
Result from this WP estimates the force necessary to the pumping system, which is useful to the next WP (WP2 “Benchtop prototype development”).
Also give some light about which sealant material will be better to use in the trials
WP2 BENCHTOP PROTOTYPE DEVELOPMENT
The goal of this work package is to design and manufacture a preliminary benchtop prototype in order to be able to test the individual components that will finally be part of the NOGAP gap filler device. This preliminary prototype had to be design to:
• Perform autonomously.
• Perform in a fully 3D-environment.
• Fill 30m length in less than 3 hours.
• Meet NLF surface finish requirements.
• Be suitable for further applications.
• Operate within an assembly line and also as a part of remote site maintenance.
The first part of this work package is related to the design of the preliminary benchtop prototype at both 2D and (technical drawings) and 3D (CAD files).
The main systems of the prototype are
- Clamping systems.
- Sealant supply.
- Guidance systems.
- Verification system.
- Curing system.
Once having received the filler materials that will supply for further tests a preliminary prototype was designed to simulate the translation along XYZ axes through flat plate coupons. This design included both hardware and software design.
Design was based in the target for the final coupon test and covers purchase, manufactures, system integration and programming tasks. Programming tasks provided feedback to design in order to adjust the final design to the requirements of the project.
Catia V5 software has been used to design the system. It includes integration of purchased parts making necessary modifications. Some video-simulations have been done to check design works correctly, at least theoretically.
In the design process a cinematic study has been done to define variable geometry nozzle requirements. Results from WP1 “Background study on filling techniques and devices” have been used to revise some parameters in the design, mainly in the pumping system.
Also design iterations based in the results from stress department have been made.
Finally has been closed the design to manufacture it. The result includes (2D drawings and 3D design). Subcontracted company has been informed in every moment of the design in order to have the provisions (material) and prevision (time) to get the product in time and quality.
The structure and the panels in which trials were done were designed as well.
CT manufactured a preliminary prototype according to the detailed design obtained. The aim of this device was to evaluate the performance of the individual systems and therefore, at this stage, the prototype was composed of basic technology.
Significant results
It has been developed a benchtop prototype with the following results:
• Integration of the vision system: Scanner and camera.
• Integration of a servo-motor with mechanical system and nozzle.
• Integration of every subsystem in the robot.
• Cinematic study of variable geometry nozzle.
• Designed panels and structure in which made the trials.
WP 3. PRIMARY BENCHTOP PROTOTYPE TRIALS
NOGAP project involves the development of a prototype able to perform filler supply, autonomous movement, gap analysis, post-application metrology and, if applicable depending on the filler features, curing. In order to size, to set-up the injection system and also to know some specific properties for each sealant to use in this project, it has been determined a tests set which is described in this report.
The main goal of this task is to correct the design errors and implement the improvements detected within the previous work package. Hence, technical objectives are the same as those for the primary design:
• Automated performance in a fully 3D-environment
• Capability to fill 30m length in less than 3h
• Surface quality within NLF tolerances
• Multiple operation
In addition to improve the individual performance, this task also included the reprogramming of software. The correct processing of data was crucial to ensure an accurate automated performance. Thus, the optimization also considered the communication between the software and the data collectors (computer vision, laser sensors and laser measurement system) and between the software and the actuators (nozzle, pump, guidance system and curing system, if applicable).
Flat coupons production has been achieved successfully due subcontractor was informed properly and includes variety to check different configurations.
Flat plate tests have been made after do some changes in the prototype according with the project´s target. Following three phases have been carried out:
• First one batch of tests with Gel instead of sealant.
• Second one batch of tests with sealant without catalyst.
• Third one batch of tests with sealant with catalyst.
Significant results
The main conclusions obtained in this work package are:
Nozzle is one of the most important elements to achieve the requirements. Fixed circular geometry nozzle is not the best solution. A fixed rectangular geometry nozzle could give a better sealant application in the gap, with less “mountain” if it is not used a variable geometry nozzle. Variable geometry nozzle could be the solution to improve the system and gets the target, but it requires more programming and integration systems and consequently is most expensive.
It is not known exactly the behavior of the sealants (fluid dynamics, viscosity,…). So it is difficult program the system because it is not repeatable neither result neither measures.
Sealant injection system provides both gel and sealant to the nozzle. When the fluid is gel there is a problem because the fluid is not controllable and still flowing when the system is stopped.
Similar problem exists with sealant material but unlike gel stops flowing after retardation elapsed time.
Vision system could be configured to read correctly the gap characteristics: direction, depth and width. Also could pass encoded information in real time either to the robot either to the PLC.
Robot is the strongest link in the chain, in the sense that it is controlled with high precision and could be programmed from the PLC or from the pendant.
Temperature and humidity could be an important factor that has not been taken in account or at least controlled. It could change the final results after curing time.
Apparently surface quality within NLF is not a requirement fulfilled in the current state of art (waiting results from Airbus UK). But it is feasible to achieve if stoppers (nozzle and sealant) are overtaken.
Time to fill 30m length in less than 3h is totally reachable based in the velocity used in the tests. Mainly velocities between 5 and 10 mm/sec involve perform the task in less than 2 hours in the worst case (1,7h). The system can be used both in 2D-environment and 3D-environment.
In brief, the main results of WP 3 are:
• Vision and camera system products are calibrated and software integration works correctly
• Fixed circle geometry nozzle it is not proper.
• Pumping system control is difficult due the delay between input signal and output sealant.
• All samples show a convex finish to the filler due the circle geometry nozzle
• All areas above the required ±100µm surface finish.
WP 4. PROTOTYPE OPTIMISATION AND DESIGN REFINEMENT
The main goal of this is to correct the design errors and implement the improvements detected within the previous work package. Hence, technical objectives are the same as those for the primary design: automated performance in a fully 3D-environment surface quality within NLF tolerances. The main systems of the prototype are:
• Clamping systems
o Test bench to 2D test
o Test bench to 3D test
• Sealant supply
o Sealant supply system for preliminary test
o Sealant supply system for final test
• Guidance systems
• Verification system
• Curing system (if applicable).
Optimization of the device design have required refinement of each individual system (Clamping, sealant supply, guidance system, verification system and curing system) as well as of the integrating software.
Improvements and corrections identified within WP3 and WP5 have been implemented in this final prototype to achieved requirements.
NOGAP filler device include basically four main systems:
• GAP filler device (Main system)
o Optimization: Has been made and test two options to test different configuration
- Fix nozzle
- Variable nozzle
• Sealant Supply System
o According to GAP filler device there are 2 options (Fix and variable)
• Guidance and verification system
o Basically this system remains as in benchtop prototype
o Some tools are necessary to assurance a correct installation
• Clamping system
o Clamping system used in the flat plate test
o Clamping system used in the double coupon test
Based in the results of flat plate trials and experience in the integration of system some systems such as pumping system or nozzle has been improved to approximate the product performance to the project’s requirements.
Following main changes:
• Two alternative nozzles includes modification in the support nozzle design, following the two alternatives:
o Fixed circular geometry output nozzle
o Adjustable geometry nozzle
• Pumping systems has 3 different chambers and sealant outputs due to following objectives:
o Check sealant supply system functionality
o Use sealant supply system with gel
o Use sealant supply system with sealant either with catalyst or without it.
Significant results
• Pumping system improved to reach enough pressing force.
• Programming improved to have best control over systems (pumpimg system, vision system, robot and nozzle). PLC is the brain of the system, as it controls the logical of the process. The programming has been done in TIA Portal of Siemens
WP 5. DOUBLE CURVED COUPON TESTS
The aim of this work package is to assess the performance of the benchtop prototype in real environments. Hence, WP5 comprises all the tests needed to validate NOGAP design before its final manufacture.
Doubled curved coupons were produced to simulate A320 NLF wing characteristics. NOGAP device was design to validate its capability to uninterruptedly fill.
After the flat plate performance validation, it was confirmed that the specifications were also met in real conditions (doubled curved panels). The results of the tests were carefully evaluated in order to identify design errors and potential improvements to be implemented. Special attention wasl paid to the nozzle performance.
FIDAMC was in charge of the physic-chemical tests of the filler material, whereas CT was responsible for tests related to the device technical performance.
In parallel to these tests, design corrections and improvement were implemented in order to optimize the device for real conditions (WP6).
Double curved coupons production has been achieved successfully due FIDAMC has provided the fiber carbon panels needed.
Double curved coupons tests have been made in the panels assembled properly in a metal tool. Following three phases have been carried out:
• First one batch of tests with Gel instead of sealant.
• Second one batch of tests with sealant without catalyst.
• Third one batch of tests with sealant with catalyst.
Significant results
• All samples show a convex finish to the filler and some areas with incomplete filling of the gap.
• All areas above the required ±100µm surface finish.
• It was suggested that this may shrink to within the required tolerance at low temperature. This reduction is lower than expected, and the filler remained well above tolerance.
• Variable geometry nozzle could be a solution.
WP 6. MANUFACTURE OF THE FINAL GAP FILLER PROTOTYPE
The aim of this work package is to finally manufacture NOGAP device including both, hardware and Software. Following the example of the previous element, manufacturing of the final prototype has been also subcontracted as it is not a core activity.
CT Ingenieros has looked after of following mechanical integrations:
• Nozzle assembly:
o Supply system and nozzle system.
o Vision system and nozzle system.
• Nozzle assembly and robot.
• PLC and auxiliary systems.
CT Ingenieros has looked after of following programming integrations:
• Vision system:
o Camera software and communication with robot.
o Scanner software and communication with PLC.
• Robot communication with PLC.
• Screen input/output in the PLC panel.
Final gap filler prototype includes few changes from the original of WP2 (Benchtop prototype development).
Finally both clamping systems were installed to can check the system in different configurations:
• Test bench for flat plate
• Test bench for double coupon
Significant results
Technical requirements for final compliance and marking to describe specific requirements to ensure correct functionality of the system:
1. Robot speed range. Limits: 0.1 mm/s to 50 mm/s (estimated).
2. Robot positioning related to benchtop:
a. The maximum height, width, etc that the robot arm can reach:
b. It can operate between two circumferences, max 1700mm forward/1400mm backward, min 314mm; at height level 505mm related to basement level (maximum operational range). Height range 2072mm / -991mm related to basement level.
3. Pumping system conditions:
a. The maximum volume of filler that can be dispensed: 862.6 mm3/s (current design).
b. Pumping system pressure range: up to 80 bars.
4. Sealant conditions: according to sealant manufacturer specifications.
5. Nozzle settings range: from 1.5 mm to 4 mm width.
6. Vision system conditions: natural or artificial direct light.
7. Other parameters:
a. Dimensions of electronic benches (three in total, maximum dimensions 1500mmx1000mmx1000mm).
b. Power supply conditions: DX100 controller: 3 phase, 240/480/575 VAC at 50/60 Hz, 2 KVA.
c. Size of the test cell/maximum size of demonstrator possible: the one matching between the two circumferences, length and width variables.
Potential Impact:
The industrial competition within the aeronautical sector is becoming ever fiercer from established, traditional rivals such as the US and even more so from new and strong challengers, notably Brazil, Canada, China, India and Russia. Regions such as the Middle East and Asia large have emerged as strong competitors for air services infrastructure. Authorities in these countries have understood the strategic nature of aviation and support their industries accordingly, enheancing competition at all levels. Due to the impossibility to complete on costs with these emerging economies, Europe has to go for technological development to remain competitive.
In this regard, Europe is entering a new age where it faces many challenges such as globalisation, a financial system in need of reform, climate change and increasing scarcity of resources. Consequently, as the communication of the European Commission “An Integrated Industrial Policy for the Globalisation Era Putting Competitiveness and Sustainability at Centre Stage” states, it is essential to increase productivity in manufacturing industry and associated services to underpin the recovery of growth and jobs, restore health and sustainability to the EU economy and help sustain our social model.
Generating € 220 billion and providing 4.5 million jobs, aerospace industry is a key driver of European competitiveness, cohesion and sustainability due to their high social and economic impact. Indeed according to the European Commission report “Flightpath 2050 Europe´s Vision”, every Euro invested in aeronautics R&D creates an equivalent additional value in the economy year thereafter.
Consequently, aeronautical technologies are catalysts for innovation and spill-over into other economic and technological sectors, thus contributing to the growth of the European economy as a whole.
In this context, the Advisory Council for Aeronautics Research in Europe defined within their Strategic Agenda the High Level Target Concepts (HTLC) to create pools of technology for deployment to whichever scenario actually develops. NOGAP project will contribute to meeting two of these ACARE HLTS and therefore Clean Sky objectives:
ULTRA GREEN AIR TRANSPORT SYSTEM
Environmental protection has been and remains a prime driver in the development of air vehicles and new transport infrastructure. HENCE SFWA Clean Sky activity will develop an all new, smart wing design with a robust “laminar performance” under typical flight conditions that will contribute to reduce emissions for the transport aircraft by reducing drag.
Natural-Laminar Flow is considered to be one of the key technologies to reduce overall drag. Where air flow over a significant portion of the wing is made smooth instead of turbulent, fuel is reduced and thus, performance is significantly improved. Drag reduction of civil transport aircraft directly concerns performance, but also indirectly, of course, cost and environment.
However, not only it is important to study wing design with different sweep and Krueger configurations, but also how to create and maintain the very high surface tolerances needed for laminar flow, including profile and finish.
Ensuring a good surface performance, and therefore the reduction of fuel burn, NOGAP contributes to meet Flight Path 2050 goals: 75% cut in CO2 emissions per passenger kilometre to support ATAG target (Carbon-neutral growth starting 2020 and a 50% overall CO2 emission reduction by 2050) and a 90% reduction in NOx emissions (These are relative to the capabilities of typical new aircraft in 2000). Indeed,, 5% of the total drag is due to roughness (E.g. joints, manufacturing) which is directly linked to fuel consumption and therefore to gas emissions.
HIGHLY COST EFFICENT AIR TRANSPORT SYSTEM
Fuel consumption represents about 22% of the direct operating costs (DOC) which is of utmost importance for the airlines, for a typical long range transport aircraft. Drag reduction directly impacts on the DOC: a drag reduction el 1% can lead to a DOC decrease of about 0.2% for a large transport aircraft. Other trade-offs corresponding to a 1% drag reduction are 1.6 tons on the operating empty weight or 10 passengers. Thus, considering the reduction of 5% of drag that is associated to roughness, NOGAP project has directly contributed to reduce 1% of transport costs.
Moreover, aircraft assembly has been a labour intensive, manual process. The results achieved under NOGAP project will enable to automatize gap filling processes to minimise the activities performed manually, and consequently, reduce the time to market while increasing accuracy. Indeed, according to the Strategic Research Agenda of Robotics European Platform, without the use of robotic technologies, cost-effective production, a pillar of European wealth, would not be possible in Europe because of relatively high labour costs. Furthermore, robot-based production increases product quality, improves work conditions and lead to an optimized use of resoruces.
NOGAP project has been therefore a step forward to achieve the Aeronautical Factory of the Future based on the concept of “Smart Factory”. The suitability of the NOGAP filler for non NFL aircrafts, which have less tight tolerance constraints, ensures the widespread impact of the aircraft manufacturing processes. The goals achieved by NOGAP project are fully consistent with those of the European Factories of the Future (EFFRA) which are defined in their multi-annual roadmap:
- Cost efficiency, with extensive adoption of standards in production machinery, equipment and controls.
- Short time to market (from the concept to new products on the market), enabled by ICT applications, which will increasingly be relevant in manufacturing industries.
- Adaptativility/re-configurability through a modular approach in production systems, in order to maximise autonomy and interaction capability of machinery and continuous re-use of existing infraestructures.
- Higher an more stable product quality through increased process robustness and accuracy according to NLF tolerances, while ensuring an easy process maintainability.
- Higher productivity under enhanced safety and ergonomics due to the reduction of works performed manually.
- Increased reusability of production systems towards global interoperable factories, which are able to provide services and develop products anytime and anywhere.
In light to these impacts, NOGAP project will contribute to the technological leadership European aeronautic industry. NOGAP break-through will be required to secure future competitive advantage, most notably in terms of air transport environmental performance and cost-efficient manufacturing.
The close cooperation with the Topic Manager, end-user of the final device, will ensure that the results of the project are from the outset oriented towards the needs of end-users, this is tailor made. Moreover, the need of automated tools is share by other manufacturing sectors such as automotive or shipbuilding. Even when accuracy and tolerances are not so strict, new technologies related to “smart factories” are being sought. Consequently NOGAP technology could be adapted to improve automation in these sectors.
DISSEMINATION AND EXPLOITAION OF NOGAP RESULTS
NOGAP is especially aware of the importance of the dissemination activities of the success of the project, since these activities facilitate widespread acceptance of the results while ensuring the protection of intellectual property rights. Rapid dis
The targeted stakeholders identified throughout the project are:
- European Technology Platforms Associations:
o Advisory Council for Aeronautics Research and Innovation in Europe (ACARE).
o Group of Aeronautical Research and Technology in Europe (GARTEUR).
o European Aerospace Cluster Partnership (EACP).
o Related national and regional Technology Platforms, associations and clusters.
- Scientific community: aeronautics, robotics and manufacturing research groups from public and private European Universities and other research institutions.
- Businesses: including aerospace companies as well as other sectors which could adapt the gap filler to their manufacturing processes such as shipbuilding industry or the automotive sector.
- The general public.
The overarching message communicated throughout the project is that NOGAP provides a new concept of aircraft manufacturing which closer to the total automation of the assembly lines, i.e. to the Factories of the Future concept, including NLF aircrafts manufacturing. EU support through Clean Sky has been acknowledged in all communications.
The key communication messages related to the project are:
- NOGAP partners have collaborated with the Topic Manager on identifying the most significant challenges in both, gap filling and sealants to develop a tailor-made device according to SFWA demonstrator specifications.
- The results of NOGAP approach have been pilot tested through flat plate and double curved coupon tests to ensure surface quality within NLF tolerances, rapid and automated filling of joints and suitable to further applications.
- Stakeholders have been invited to follow NOGAP progress through partner’s websites but also to attend the final strategic conference to learn about the results of the project, not only regarding NLF aircrafts, but also increasing the degree of automation, production rates and accuracy in non NLF crafts, ship building and motor manufacturing.
The main dissemination activities carried out, relating to the project are listed below:
• EVENTS ATTENDANCE, where different promotional activities through meetings with different customers/companies:
- ILA Berlin Air Show, organized by BLDI (German Aerospace Industries Association) on May 20th-25th, 2014. This exhibition is focused on civil aviation, space, defence and security, helicopters, equipment, engines and materials.
- Eurosatory, organized by GICAT, the French Land Defense and Security Industry Association, June 16th-26th 2014.
- Several promotional activities activities through meetings with different customers were carried out.
- Farnborough international show, organized by Norwest Aerospace Alliance. It is one of the world´s largest exhibitions and air displays first-class business opportunities for the global aerospace industry. July14th-20th 2014.
It is expected to attend some other exhibitions/ conferences in order to get the widest dissemination of the foreground generated in the project:
- Composite Days, organized by Airbus Group in October 28th-29th 2014 in Toulouse (France).
- International Paris Air Show Le Bourget in June 15th-21st 2015 in Paris (France).
• MEDIA AND PRINTING ACTIONS
- Article published on aerodefensa.com website on the 14/09/2012.
- Article published on clusteraerocv.es website on the 14/09/2012.
- Article published on aerotendencias.com website on the 13/09/2012.
- Article to be included in AEC (Asociación Española de la Calidad) quarterly publication on the 15/09/2014.
- Project poster and project leaflets have been printed.
Moreover, a patent is being released wihin NOGAP project:
DESCRIPTION PLACE NUMBER STATE
Method and system for fluid dossification SPAIN PCT/ES 2014/000008 On progress
List of Websites:
www.ctingenieros.es/nogap
Ruben Piornedo: rpiornedo@ctingenieros.es
José Gonzalez: jagonzalez@ctingenieros.es
Bernardo López: Bernardo.Lopez@fidamc.es
Miguel Ángel Torrijos: Miguel.Torrijos@fidamc.es
However, the stringent NLF surface requirements are difficult to be reached with conventional manufacturing processes. NOGAP project has developed a fully automated gap filler device that is able to performance in a 3D environment and achieve surface finish within NLF tolerances at high production rates.
To achieve its purpose, NOGAP project has integrated different systems in a single multifunction robot:
• Computer Vision system and 2D laser measurement device integrated in a verification system, for guidance, surface scanning and post-application metrology control.
• Innovative filler injection system with flow software control and variable-geometry nozzles (under patent development).
It can be said that NOGAP project has developed the first automated gap filler device for aircraft manufacturing that is accurate enough to maintain the surface quality to NLF tolerances. Technological leaps achieved in the NOGAP device are:
• Fully automated and easy to use gap filler device.
• Multi-task device, as all filling stages (gap analysis, sealant mixing, curing, post application metrology and curing) are performed by one single robot.
• No direct manipulation of the sealant by the operators, avoiding high number of errors and reducing the time for application.
• Surface finish requirements verified by computer vision and laser sensors.
• Flexible gap filler device that can be used to fill other joints (i.e. chord wise joints, countersinks or minor service defects), in contrast to actual specific tooling developed to specific aeroestructures of a specific aircraft programme.
• High production rate in contrast to high application and rework time of actual devices.
NOGAP project has made a significant contribution to the flexibility and automation of assembly tooling, which is a step forward to achieve the Aeronautical Factories of the Future based on the concept of “Smart Factory”.
Project Context and Objectives:
Current sealant materials consist of two components, base and curing agent, which reacts at room temperature. Base material is based upon standar polysulphide sealan technology, whereas curing agents are oxygen donors which react with thiol groups and which start the process of crosslinking by polycondensation.
This sealant is also used in automotive and building industry, even though aeronautics is the principal market due to its chemical resistance to fuel. Formulation is adjusted according to the specific application and the properties sought.
SEALANT SUPPLY
The two components of the aeronautical sealants are supplied in two possible configurations:
a. Two-component Kit (packed in a wide variety of weights), which are mixed together according to a relation specified by the supplier. The mixture of the two components could be performed manual or semi-automatic.
• Manual Mixing (KIT).
In this case the mixture is carried out by the operator by manual mixing adding the hardener base in suitable proportions.
• Semi-automatic Mode: Mixing machine (KIT)
This procedure is typically used for cord sealants but it may also be used for seam fillers. The equipment used for mechanical mixing of this type of sealant is planetary and can be equipped with a cooling system to prevent mixture heating.
Once the mixture is ready, it is packed in cartridges similar to Semkits by extruding the mixture with a press. These packages are then frozen at -70ºC and stored at -60ªC until use.
This technique implies a significant consumption of time and resources as well as an inherent risk of handling errors introduced by operators.
b. SemKit or individual two-chamber package, which contains precise weights of both components (typically 130 g), which are mixed by hand or with a specific pneumatic equipment. SemKits are packages prepared by the manufacturer with the exact amounts of base and catalyst compounds but without being mixed. The mixture is performed by rotation of a plunger which enters the base into the catalyst. The rotation of the plunger can be done manually (in accordance with the number of strokes that have been defined by the manufacturer) or with a SemKit automatic mixer as shown in the following figure.
A priori, the use of Semkit has certain advantages over the use of a two-component kit. However, their use is not widespread since the cost of the products in this type of package is considerably higher.
One of the advantages of using SemKits is that the manufacturer provides appropriate proportional amounts of base and catalyst. Therefore, potential weighing errors that may occur in the mixing of Kits are avoided. In addition, other stages are also avoided such as pressing packings for filling or sealant freezing and defrosting.
Recently, end-users have introduced a stage for pre-mixing and freezing the sealant before its application in aerostructures assembly processes. The process involves the feeding of the base and the curing agent to a mixing chamber, extruding the mixture to SemKit-type packages, freezing instantaneously and subsequent storage in freezing chambers.
Premixed and frozen sealants have the great advantage of removing the mixing process in assembly areas. Consequently, as a result of being applied once they are defrosted, as a single component, they save time in manufacturing. Additionally, the cleaning of the mixers which involves the use of organic solvents at the shop floor is avoided.
However, despite these advantages, worsening of some of the properties of these sealants has been detected (For example, reduction of the time for application, or application problems due to a nonhomogeneous defrost). These problems are having a negative impact on productivity, since it involves the demoulding of the sealant, further conditioning of the surfaces and reapplication of the filler.
POMPING AND METERING SYSTEMS
As detailed above, the current aircraft filler is a two-component sealant, so metering and pumping systems are particularly relevant for a correct application. Currently, guns for the application of bicomponent sealants where the metering and pumping are performed by manual operation are commonly used.
Aeronautical sealants are not the only two-component ones. In fact there are other bicomponent fillers, resins and chemicals that have already encountered the same difficulties that now arise in the aeronautical sector. Thus, other sectors are needed to be considered as baseline since there is no previous reference to automatic application of sealants in aeronautics. However, the particular characteristics of aeronautical sealants influence the process and therefore its application technology.
Bicomponent pumping and metering systems are normally composed of two independent tanks (one for each reagent) and a circuit consisting of filters, heat exchangers and metering pumps that provide the specific temperature and pressure to the sealant to achieve optimal conditions when reaching the mixhead. Moreover, a recirculation system from the mixhead is mostly included to avoid curing and therefore blockage.
Although these systems are versatile, they are primarily designed for dispensing rigid foam, cold-cured flexible foam, padding foam, integral skin foam or viscoelastic foams; and can be used with light sealants under specific circumstances.
Current technology is not optimized for sealants, and specifically does not apply to aeronautical ones. Their special features (density and viscosity) complicate the process and affect the design of pumps, heat exchangers, filters, recirculation system and mixhead. Thus, the high reliability demanded by aeronautics makes it completely discard this option.
These machines are designed for serial processes in which the bicomponent receiver element is moving, maintaining the gap filler device in place, and performing the same operation continuously. As a result, this concept does not take into account factors such as weight, compactness, transportability, flexibility of tools (mostly heads), ease of parameterization and ability to react to the parameterization.
These assumptions are precisely contrary to what happens in the aeronautical sector. Due to the size of the pieces, manufacturing tools move around them needing highly specific and particular machinery. Consequently, the concept of these devices is not valid for NOGAP project.
AUTOMATED GAP FILLER DEVICES
Robots are commonly used for the application of cords of sealant in the automotive industry, such as in sealing windows and windshields. This industry uses liquid and pasty sealant that is pumped to the robotic spray gun which regulates the flow of sealant to be applied.
The robot, along the programmed path, projects the sealant which solidifies upon contact with air. In this process, in addition to the accurate control of the robot path, it is extremely important to achieve a synchronized control of its speed and the sealant flow supplied by the gun since the amount of material projected depends on these two factors. Thus, gap filler devices are usually hung from the specific piece requiring continuous control of the robot path (position and speed accurately regulated) and including the regulation of the sealant flow provided in accordance with the robot speed.
Due to the specific characteristics and the high accuracy needed in aeronautics, automated gap filler devices are not known in this sector beyond laboratory tests and therefore, they are still under development.
The most advanced automated devices are used for the application of seam sealant in the automotive industry (Different viscosity from aeronautical one). These robots are installed on a rail and have the degrees of freedom needed for the application of sealant in the shortest time. This nozzle is normally located in a 3-axis Cartesian system or in a 6-axis robot.
Different companies supply robots that could be adapted to include a specific nozzle for the application of sealant in the automotive industry. There are different models that perform the task: Anchored to the ground; installed on a rail through which the device moves in a specific direction; installed on frames, so that the robot performs from the upper working area.
The software is the main core of the control unit and includes all the basic functions, such as, path planning, management of inputs and outputs, and additional functions as for example curing.
COMPUTER VISION
The strict requirements and the need of high accuracy of the aeronautical sector force the manufactures to develop new systems suitable for post-application metrology, such as computer vision. This technology could be used to verify tolerances, this is panel misalignment, gap geometry and filler tolerance. Nevertheless, the drawback of vision systems is their dependence of illumination and the differentiation of textures.
There are different approaches to control sealing depending on the type of material to be sealed or the filler itself. However, the usual trend is to use laser technology along with a camera in order to detect any divergence of the laser with respect to the expected curve. All these methods work with laser triangulation method. This method can be extended by dividing the laser beam into multiple lines to have several references in the same image. Thus, the effectiveness of the control will be increased, and in addition, the direction of filling could be defined to implement corrections.
Despite the degree of development for automotive applications, commercial gap filler devices do not meet aeronautics sealing requirements, and therefore the restrictive NLF tolerances:
• Sealant Composition: The device design depends entirely on the characteristics of the sealant and current aeronautical one has certain characteristics that differ from automotive sealant (two-component, viscosity, density). Moreover, it is know that current aeronautical filler material has shrinkage problems.
• Accuracy: Aerospace need to develop expensive specialised automated filling machines because standard industrial robots lack the accuracy required for NLF aircraft assembly.
• Manufacturing environment: Devices on the market are designed primarily for the automotive industry which uses a completely different manufacturing scheme. Automotive robots are also designed to perform a single task thousands of times, whereas the lower production rates and longer cycle times for aircraft demand robots that can perform more than one function.
• Software: Due to the accuracy required, it is necessary to develop specific software that included computer vision systems to follow patterns without losing the position.
OBJECTIVES
In light of the foregoing the objectives of NOGAP project were:
• Evaluate new filler materials (toughened epoxy fillers and UV curable sealants) that avoid mixing problems, improve surface finish, reduce shrinkage and enable automation, while ensuring good adhesion, flexibility, fluid resistance, temperature stability.
• Substitute current two-component fillers for new sealant materials and therefore, drastically change existing pumping systems and avoid the associated problems stated above. Moreover, integrate a smart nozzle able to adapt its geometry according to the need of filler detected by a sensor. Hence, the accuracy of NOGAP metering system is largely higher.
• Develop a multi-task automated seven-axis robot able to independently perform, detect and analyze gaps, apply specific amounts of sealant depending on the specific size of the gap, curing if necessary and verify surface finishing. The also incorporate software to be programed according to the surface finish tolerances demanded. Thus, NOGAP technology is flexible to fill any type of gap within standard or NLF tolerances.The combination of rapidity and accuracy will be the main constraints for NOGAP technology development.
• Develop a combination of computer vision and laser sensors in order to avoid illumination problems, the limitation to painted surfaces, define a virtual plane to control the height and the application of sealant at right angles, and to evaluate surface finish.
Project Results:
The main scientific and technical results achieved in each technical work package of the project are shown below:
WP1. Background study on filling techniques and devices
The purpose of this work package was to outline state of the arte technology for gap filling.
Background studies of commercial aerospace surface smoothing sealants were done with the aim of reporting and identifying all the potential design solutions for NLF aircraft wings manufacturing.
A range of sealant types was listed in order to fulfill the various applications, but polysulphide sealants are predominant. Polysulphides offer a balance of good application and cure characteristics from a manufacturing engineering perspective with good all-round performance in terms of physical properties and chemical resistance over a wide temperature range. However, they have limitations in performance terms which are their limited resistance to phosphate ester hydraulic fluid and their limited long-term oxidative stability. The most commonly used cure agents for polysulphides is manganese dioxide. However, epoxy agents for polythioether systems are also available .
Emerging drivers for the future development of surface smoothing aerospace sealant technologies, such as new polisulphide, and UV-cured sealants as well, are a key point for lower densities, lower shrinkage; improve surface finish helping to achieve Natural Laminar Flow aircraft wings surfaces and also to enable the surface smoothing process automation. Unfortunately, there is no further information reported due to the early stage of the developments.
Moreover, in order to help in the improvement of commercial sealants properties, it has been listed the most influent modifiers that allow a change in the sealants properties. These modifiers are adhesion additives, accelerators, fillers, solvents and adhesion promoters. Furthermore, it was explained the cure chemistry that sealants and the main chemical curing and adhesion mechanisms.
CT and FIDAMC have made a batch of test to determinate the properties of proposed sealant materials of 3 different suppliers (PPG, Chemetall and SIKA). Both commercial and innovative sealants are studied including current polysulphide sealant technology, toughened epoxy fillers and UV curable sealant.
In total 7 different products (different in properties or format) have been characterized, main characteristics are the following:
• Viscosity
• Degree of contraction from the fresh state to the cured state.
• Necessary force to apply in the pumping system.
Significant results
Result from this WP estimates the force necessary to the pumping system, which is useful to the next WP (WP2 “Benchtop prototype development”).
Also give some light about which sealant material will be better to use in the trials
WP2 BENCHTOP PROTOTYPE DEVELOPMENT
The goal of this work package is to design and manufacture a preliminary benchtop prototype in order to be able to test the individual components that will finally be part of the NOGAP gap filler device. This preliminary prototype had to be design to:
• Perform autonomously.
• Perform in a fully 3D-environment.
• Fill 30m length in less than 3 hours.
• Meet NLF surface finish requirements.
• Be suitable for further applications.
• Operate within an assembly line and also as a part of remote site maintenance.
The first part of this work package is related to the design of the preliminary benchtop prototype at both 2D and (technical drawings) and 3D (CAD files).
The main systems of the prototype are
- Clamping systems.
- Sealant supply.
- Guidance systems.
- Verification system.
- Curing system.
Once having received the filler materials that will supply for further tests a preliminary prototype was designed to simulate the translation along XYZ axes through flat plate coupons. This design included both hardware and software design.
Design was based in the target for the final coupon test and covers purchase, manufactures, system integration and programming tasks. Programming tasks provided feedback to design in order to adjust the final design to the requirements of the project.
Catia V5 software has been used to design the system. It includes integration of purchased parts making necessary modifications. Some video-simulations have been done to check design works correctly, at least theoretically.
In the design process a cinematic study has been done to define variable geometry nozzle requirements. Results from WP1 “Background study on filling techniques and devices” have been used to revise some parameters in the design, mainly in the pumping system.
Also design iterations based in the results from stress department have been made.
Finally has been closed the design to manufacture it. The result includes (2D drawings and 3D design). Subcontracted company has been informed in every moment of the design in order to have the provisions (material) and prevision (time) to get the product in time and quality.
The structure and the panels in which trials were done were designed as well.
CT manufactured a preliminary prototype according to the detailed design obtained. The aim of this device was to evaluate the performance of the individual systems and therefore, at this stage, the prototype was composed of basic technology.
Significant results
It has been developed a benchtop prototype with the following results:
• Integration of the vision system: Scanner and camera.
• Integration of a servo-motor with mechanical system and nozzle.
• Integration of every subsystem in the robot.
• Cinematic study of variable geometry nozzle.
• Designed panels and structure in which made the trials.
WP 3. PRIMARY BENCHTOP PROTOTYPE TRIALS
NOGAP project involves the development of a prototype able to perform filler supply, autonomous movement, gap analysis, post-application metrology and, if applicable depending on the filler features, curing. In order to size, to set-up the injection system and also to know some specific properties for each sealant to use in this project, it has been determined a tests set which is described in this report.
The main goal of this task is to correct the design errors and implement the improvements detected within the previous work package. Hence, technical objectives are the same as those for the primary design:
• Automated performance in a fully 3D-environment
• Capability to fill 30m length in less than 3h
• Surface quality within NLF tolerances
• Multiple operation
In addition to improve the individual performance, this task also included the reprogramming of software. The correct processing of data was crucial to ensure an accurate automated performance. Thus, the optimization also considered the communication between the software and the data collectors (computer vision, laser sensors and laser measurement system) and between the software and the actuators (nozzle, pump, guidance system and curing system, if applicable).
Flat coupons production has been achieved successfully due subcontractor was informed properly and includes variety to check different configurations.
Flat plate tests have been made after do some changes in the prototype according with the project´s target. Following three phases have been carried out:
• First one batch of tests with Gel instead of sealant.
• Second one batch of tests with sealant without catalyst.
• Third one batch of tests with sealant with catalyst.
Significant results
The main conclusions obtained in this work package are:
Nozzle is one of the most important elements to achieve the requirements. Fixed circular geometry nozzle is not the best solution. A fixed rectangular geometry nozzle could give a better sealant application in the gap, with less “mountain” if it is not used a variable geometry nozzle. Variable geometry nozzle could be the solution to improve the system and gets the target, but it requires more programming and integration systems and consequently is most expensive.
It is not known exactly the behavior of the sealants (fluid dynamics, viscosity,…). So it is difficult program the system because it is not repeatable neither result neither measures.
Sealant injection system provides both gel and sealant to the nozzle. When the fluid is gel there is a problem because the fluid is not controllable and still flowing when the system is stopped.
Similar problem exists with sealant material but unlike gel stops flowing after retardation elapsed time.
Vision system could be configured to read correctly the gap characteristics: direction, depth and width. Also could pass encoded information in real time either to the robot either to the PLC.
Robot is the strongest link in the chain, in the sense that it is controlled with high precision and could be programmed from the PLC or from the pendant.
Temperature and humidity could be an important factor that has not been taken in account or at least controlled. It could change the final results after curing time.
Apparently surface quality within NLF is not a requirement fulfilled in the current state of art (waiting results from Airbus UK). But it is feasible to achieve if stoppers (nozzle and sealant) are overtaken.
Time to fill 30m length in less than 3h is totally reachable based in the velocity used in the tests. Mainly velocities between 5 and 10 mm/sec involve perform the task in less than 2 hours in the worst case (1,7h). The system can be used both in 2D-environment and 3D-environment.
In brief, the main results of WP 3 are:
• Vision and camera system products are calibrated and software integration works correctly
• Fixed circle geometry nozzle it is not proper.
• Pumping system control is difficult due the delay between input signal and output sealant.
• All samples show a convex finish to the filler due the circle geometry nozzle
• All areas above the required ±100µm surface finish.
WP 4. PROTOTYPE OPTIMISATION AND DESIGN REFINEMENT
The main goal of this is to correct the design errors and implement the improvements detected within the previous work package. Hence, technical objectives are the same as those for the primary design: automated performance in a fully 3D-environment surface quality within NLF tolerances. The main systems of the prototype are:
• Clamping systems
o Test bench to 2D test
o Test bench to 3D test
• Sealant supply
o Sealant supply system for preliminary test
o Sealant supply system for final test
• Guidance systems
• Verification system
• Curing system (if applicable).
Optimization of the device design have required refinement of each individual system (Clamping, sealant supply, guidance system, verification system and curing system) as well as of the integrating software.
Improvements and corrections identified within WP3 and WP5 have been implemented in this final prototype to achieved requirements.
NOGAP filler device include basically four main systems:
• GAP filler device (Main system)
o Optimization: Has been made and test two options to test different configuration
- Fix nozzle
- Variable nozzle
• Sealant Supply System
o According to GAP filler device there are 2 options (Fix and variable)
• Guidance and verification system
o Basically this system remains as in benchtop prototype
o Some tools are necessary to assurance a correct installation
• Clamping system
o Clamping system used in the flat plate test
o Clamping system used in the double coupon test
Based in the results of flat plate trials and experience in the integration of system some systems such as pumping system or nozzle has been improved to approximate the product performance to the project’s requirements.
Following main changes:
• Two alternative nozzles includes modification in the support nozzle design, following the two alternatives:
o Fixed circular geometry output nozzle
o Adjustable geometry nozzle
• Pumping systems has 3 different chambers and sealant outputs due to following objectives:
o Check sealant supply system functionality
o Use sealant supply system with gel
o Use sealant supply system with sealant either with catalyst or without it.
Significant results
• Pumping system improved to reach enough pressing force.
• Programming improved to have best control over systems (pumpimg system, vision system, robot and nozzle). PLC is the brain of the system, as it controls the logical of the process. The programming has been done in TIA Portal of Siemens
WP 5. DOUBLE CURVED COUPON TESTS
The aim of this work package is to assess the performance of the benchtop prototype in real environments. Hence, WP5 comprises all the tests needed to validate NOGAP design before its final manufacture.
Doubled curved coupons were produced to simulate A320 NLF wing characteristics. NOGAP device was design to validate its capability to uninterruptedly fill.
After the flat plate performance validation, it was confirmed that the specifications were also met in real conditions (doubled curved panels). The results of the tests were carefully evaluated in order to identify design errors and potential improvements to be implemented. Special attention wasl paid to the nozzle performance.
FIDAMC was in charge of the physic-chemical tests of the filler material, whereas CT was responsible for tests related to the device technical performance.
In parallel to these tests, design corrections and improvement were implemented in order to optimize the device for real conditions (WP6).
Double curved coupons production has been achieved successfully due FIDAMC has provided the fiber carbon panels needed.
Double curved coupons tests have been made in the panels assembled properly in a metal tool. Following three phases have been carried out:
• First one batch of tests with Gel instead of sealant.
• Second one batch of tests with sealant without catalyst.
• Third one batch of tests with sealant with catalyst.
Significant results
• All samples show a convex finish to the filler and some areas with incomplete filling of the gap.
• All areas above the required ±100µm surface finish.
• It was suggested that this may shrink to within the required tolerance at low temperature. This reduction is lower than expected, and the filler remained well above tolerance.
• Variable geometry nozzle could be a solution.
WP 6. MANUFACTURE OF THE FINAL GAP FILLER PROTOTYPE
The aim of this work package is to finally manufacture NOGAP device including both, hardware and Software. Following the example of the previous element, manufacturing of the final prototype has been also subcontracted as it is not a core activity.
CT Ingenieros has looked after of following mechanical integrations:
• Nozzle assembly:
o Supply system and nozzle system.
o Vision system and nozzle system.
• Nozzle assembly and robot.
• PLC and auxiliary systems.
CT Ingenieros has looked after of following programming integrations:
• Vision system:
o Camera software and communication with robot.
o Scanner software and communication with PLC.
• Robot communication with PLC.
• Screen input/output in the PLC panel.
Final gap filler prototype includes few changes from the original of WP2 (Benchtop prototype development).
Finally both clamping systems were installed to can check the system in different configurations:
• Test bench for flat plate
• Test bench for double coupon
Significant results
Technical requirements for final compliance and marking to describe specific requirements to ensure correct functionality of the system:
1. Robot speed range. Limits: 0.1 mm/s to 50 mm/s (estimated).
2. Robot positioning related to benchtop:
a. The maximum height, width, etc that the robot arm can reach:
b. It can operate between two circumferences, max 1700mm forward/1400mm backward, min 314mm; at height level 505mm related to basement level (maximum operational range). Height range 2072mm / -991mm related to basement level.
3. Pumping system conditions:
a. The maximum volume of filler that can be dispensed: 862.6 mm3/s (current design).
b. Pumping system pressure range: up to 80 bars.
4. Sealant conditions: according to sealant manufacturer specifications.
5. Nozzle settings range: from 1.5 mm to 4 mm width.
6. Vision system conditions: natural or artificial direct light.
7. Other parameters:
a. Dimensions of electronic benches (three in total, maximum dimensions 1500mmx1000mmx1000mm).
b. Power supply conditions: DX100 controller: 3 phase, 240/480/575 VAC at 50/60 Hz, 2 KVA.
c. Size of the test cell/maximum size of demonstrator possible: the one matching between the two circumferences, length and width variables.
Potential Impact:
The industrial competition within the aeronautical sector is becoming ever fiercer from established, traditional rivals such as the US and even more so from new and strong challengers, notably Brazil, Canada, China, India and Russia. Regions such as the Middle East and Asia large have emerged as strong competitors for air services infrastructure. Authorities in these countries have understood the strategic nature of aviation and support their industries accordingly, enheancing competition at all levels. Due to the impossibility to complete on costs with these emerging economies, Europe has to go for technological development to remain competitive.
In this regard, Europe is entering a new age where it faces many challenges such as globalisation, a financial system in need of reform, climate change and increasing scarcity of resources. Consequently, as the communication of the European Commission “An Integrated Industrial Policy for the Globalisation Era Putting Competitiveness and Sustainability at Centre Stage” states, it is essential to increase productivity in manufacturing industry and associated services to underpin the recovery of growth and jobs, restore health and sustainability to the EU economy and help sustain our social model.
Generating € 220 billion and providing 4.5 million jobs, aerospace industry is a key driver of European competitiveness, cohesion and sustainability due to their high social and economic impact. Indeed according to the European Commission report “Flightpath 2050 Europe´s Vision”, every Euro invested in aeronautics R&D creates an equivalent additional value in the economy year thereafter.
Consequently, aeronautical technologies are catalysts for innovation and spill-over into other economic and technological sectors, thus contributing to the growth of the European economy as a whole.
In this context, the Advisory Council for Aeronautics Research in Europe defined within their Strategic Agenda the High Level Target Concepts (HTLC) to create pools of technology for deployment to whichever scenario actually develops. NOGAP project will contribute to meeting two of these ACARE HLTS and therefore Clean Sky objectives:
ULTRA GREEN AIR TRANSPORT SYSTEM
Environmental protection has been and remains a prime driver in the development of air vehicles and new transport infrastructure. HENCE SFWA Clean Sky activity will develop an all new, smart wing design with a robust “laminar performance” under typical flight conditions that will contribute to reduce emissions for the transport aircraft by reducing drag.
Natural-Laminar Flow is considered to be one of the key technologies to reduce overall drag. Where air flow over a significant portion of the wing is made smooth instead of turbulent, fuel is reduced and thus, performance is significantly improved. Drag reduction of civil transport aircraft directly concerns performance, but also indirectly, of course, cost and environment.
However, not only it is important to study wing design with different sweep and Krueger configurations, but also how to create and maintain the very high surface tolerances needed for laminar flow, including profile and finish.
Ensuring a good surface performance, and therefore the reduction of fuel burn, NOGAP contributes to meet Flight Path 2050 goals: 75% cut in CO2 emissions per passenger kilometre to support ATAG target (Carbon-neutral growth starting 2020 and a 50% overall CO2 emission reduction by 2050) and a 90% reduction in NOx emissions (These are relative to the capabilities of typical new aircraft in 2000). Indeed,, 5% of the total drag is due to roughness (E.g. joints, manufacturing) which is directly linked to fuel consumption and therefore to gas emissions.
HIGHLY COST EFFICENT AIR TRANSPORT SYSTEM
Fuel consumption represents about 22% of the direct operating costs (DOC) which is of utmost importance for the airlines, for a typical long range transport aircraft. Drag reduction directly impacts on the DOC: a drag reduction el 1% can lead to a DOC decrease of about 0.2% for a large transport aircraft. Other trade-offs corresponding to a 1% drag reduction are 1.6 tons on the operating empty weight or 10 passengers. Thus, considering the reduction of 5% of drag that is associated to roughness, NOGAP project has directly contributed to reduce 1% of transport costs.
Moreover, aircraft assembly has been a labour intensive, manual process. The results achieved under NOGAP project will enable to automatize gap filling processes to minimise the activities performed manually, and consequently, reduce the time to market while increasing accuracy. Indeed, according to the Strategic Research Agenda of Robotics European Platform, without the use of robotic technologies, cost-effective production, a pillar of European wealth, would not be possible in Europe because of relatively high labour costs. Furthermore, robot-based production increases product quality, improves work conditions and lead to an optimized use of resoruces.
NOGAP project has been therefore a step forward to achieve the Aeronautical Factory of the Future based on the concept of “Smart Factory”. The suitability of the NOGAP filler for non NFL aircrafts, which have less tight tolerance constraints, ensures the widespread impact of the aircraft manufacturing processes. The goals achieved by NOGAP project are fully consistent with those of the European Factories of the Future (EFFRA) which are defined in their multi-annual roadmap:
- Cost efficiency, with extensive adoption of standards in production machinery, equipment and controls.
- Short time to market (from the concept to new products on the market), enabled by ICT applications, which will increasingly be relevant in manufacturing industries.
- Adaptativility/re-configurability through a modular approach in production systems, in order to maximise autonomy and interaction capability of machinery and continuous re-use of existing infraestructures.
- Higher an more stable product quality through increased process robustness and accuracy according to NLF tolerances, while ensuring an easy process maintainability.
- Higher productivity under enhanced safety and ergonomics due to the reduction of works performed manually.
- Increased reusability of production systems towards global interoperable factories, which are able to provide services and develop products anytime and anywhere.
In light to these impacts, NOGAP project will contribute to the technological leadership European aeronautic industry. NOGAP break-through will be required to secure future competitive advantage, most notably in terms of air transport environmental performance and cost-efficient manufacturing.
The close cooperation with the Topic Manager, end-user of the final device, will ensure that the results of the project are from the outset oriented towards the needs of end-users, this is tailor made. Moreover, the need of automated tools is share by other manufacturing sectors such as automotive or shipbuilding. Even when accuracy and tolerances are not so strict, new technologies related to “smart factories” are being sought. Consequently NOGAP technology could be adapted to improve automation in these sectors.
DISSEMINATION AND EXPLOITAION OF NOGAP RESULTS
NOGAP is especially aware of the importance of the dissemination activities of the success of the project, since these activities facilitate widespread acceptance of the results while ensuring the protection of intellectual property rights. Rapid dis
The targeted stakeholders identified throughout the project are:
- European Technology Platforms Associations:
o Advisory Council for Aeronautics Research and Innovation in Europe (ACARE).
o Group of Aeronautical Research and Technology in Europe (GARTEUR).
o European Aerospace Cluster Partnership (EACP).
o Related national and regional Technology Platforms, associations and clusters.
- Scientific community: aeronautics, robotics and manufacturing research groups from public and private European Universities and other research institutions.
- Businesses: including aerospace companies as well as other sectors which could adapt the gap filler to their manufacturing processes such as shipbuilding industry or the automotive sector.
- The general public.
The overarching message communicated throughout the project is that NOGAP provides a new concept of aircraft manufacturing which closer to the total automation of the assembly lines, i.e. to the Factories of the Future concept, including NLF aircrafts manufacturing. EU support through Clean Sky has been acknowledged in all communications.
The key communication messages related to the project are:
- NOGAP partners have collaborated with the Topic Manager on identifying the most significant challenges in both, gap filling and sealants to develop a tailor-made device according to SFWA demonstrator specifications.
- The results of NOGAP approach have been pilot tested through flat plate and double curved coupon tests to ensure surface quality within NLF tolerances, rapid and automated filling of joints and suitable to further applications.
- Stakeholders have been invited to follow NOGAP progress through partner’s websites but also to attend the final strategic conference to learn about the results of the project, not only regarding NLF aircrafts, but also increasing the degree of automation, production rates and accuracy in non NLF crafts, ship building and motor manufacturing.
The main dissemination activities carried out, relating to the project are listed below:
• EVENTS ATTENDANCE, where different promotional activities through meetings with different customers/companies:
- ILA Berlin Air Show, organized by BLDI (German Aerospace Industries Association) on May 20th-25th, 2014. This exhibition is focused on civil aviation, space, defence and security, helicopters, equipment, engines and materials.
- Eurosatory, organized by GICAT, the French Land Defense and Security Industry Association, June 16th-26th 2014.
- Several promotional activities activities through meetings with different customers were carried out.
- Farnborough international show, organized by Norwest Aerospace Alliance. It is one of the world´s largest exhibitions and air displays first-class business opportunities for the global aerospace industry. July14th-20th 2014.
It is expected to attend some other exhibitions/ conferences in order to get the widest dissemination of the foreground generated in the project:
- Composite Days, organized by Airbus Group in October 28th-29th 2014 in Toulouse (France).
- International Paris Air Show Le Bourget in June 15th-21st 2015 in Paris (France).
• MEDIA AND PRINTING ACTIONS
- Article published on aerodefensa.com website on the 14/09/2012.
- Article published on clusteraerocv.es website on the 14/09/2012.
- Article published on aerotendencias.com website on the 13/09/2012.
- Article to be included in AEC (Asociación Española de la Calidad) quarterly publication on the 15/09/2014.
- Project poster and project leaflets have been printed.
Moreover, a patent is being released wihin NOGAP project:
DESCRIPTION PLACE NUMBER STATE
Method and system for fluid dossification SPAIN PCT/ES 2014/000008 On progress
List of Websites:
www.ctingenieros.es/nogap
Ruben Piornedo: rpiornedo@ctingenieros.es
José Gonzalez: jagonzalez@ctingenieros.es
Bernardo López: Bernardo.Lopez@fidamc.es
Miguel Ángel Torrijos: Miguel.Torrijos@fidamc.es