Final Report Summary - ASPIRATE (Increase of productivity, safety, greenness and cleanliness in the machining of carbon fibre-reinforced composites)
Executive summary:
The aerospace industry has been the key market for pushing this big leap towards industrial production of fibre reinforced composite components. Nowadays, the development of the production techniques and the reduction on production costs have allow wider applications in emerging markets, such as, wind energy, deep water oil platforms and transportation, as well as in more traditional scenarios like construction and civil structures or sporting goods sector.
Nevertheless, some phases of the composite products production chain present several hazards for the operator's health as well as the environment impact.
The ASPIRATE project, funded by the 'Research for the benefit of SMEs' programme, aims to give and answer to the aforementioned drawbacks, eliminating the dust and chips completely from the working area, without affecting the operator, contributing to the cleanliness of the workpiece and maintaining the maximum flexibility of the process, as no external or peripherals.
The technology resultant from this project is based on the machining with internal chip and dust evacuation, through a hollow tool connected to a standard HSK tool-holder, a modified spindle and a suction pump attached at its rear.
The preliminary tests made on carbon and glass fibre-reinforced plastics (CFRP and GFRP), opened exciting application possibilities. ASPIRATE consortium involves several small and medium-sized enterprises (SMEs) from these sectors, as well as, research and technological development (RTD) actors with the experience and skills for ramping up these developments to real industrial applications.
The industrial consortium is formed by 4 SMEs from 3 European countries. All these SMEs are also intensive in research and development (R&D), as it is the case of INVENT GMBH (Braunschweig, Germany) in the design and development of aerospace components and structural applications in CFRP and GFRP, the company RHO-BEST (Innsbruck, Austria) in the development of advanced coating materials and processes, ORTZA S. Coop. (Huarte, Spain), a machine tool producer SME, with a clear target on the design and building of specialised machines for machining composite materials and finally, ZUBIOLA S. Coop. (Azkoitia, Spain), as manufacturer of special and customised cutting tools.
It is worth to mention that the beneficiary company ORTZA S. Coop. decided to leave the project on February 2011 due to the hard financial conditions this company was suffering due to the economic crisis.
After a validation process made jointly with the REA officers, it was agreed to replace ORTZA S. Coop. company by the Spanish SME company EGURKO S. Coop, which is also focusing its activity on the production of machine tools for the wood sector with high interest on the evolution of its machines to the design and production of machines for the composite industry.
The final entrance of EGURKO S. Coop. to the consortium was effective on 15 February 2011 and it was also stated on the 1st amendment to the contract finally signed by the REA director on May 2011.
The coordinator of the project is IDEKO-IK4, a Spanish research centre specialised on machine tools, production equipment and manufacturing processes, with a comprehensive trajectory on Framework Programme (FP) research activities. The other RTD is the Fraunhofer IST, with large experience also on the participation of European Union (EU)-funded projects.
ASPIRATE project did start on 1 June 2009 and ended on 30 May 2011, so it has lasted a total of 24 months. In this period some key achievements have been obtained, such as the development of a complete system for the machining of CFRP materials extracting the chips and dust through the tool-holder-spindle-pump system, the design, production and testing of hollow cutting tools with brazed diamond coated inserts, as well as the corresponding validation of the system, tools and process parameters over real industrial test cases.
In the first period (month 0 to month 12) the consortium completed the design and implementation of the machine tool, which was ready to accomplish the machining tests. ORT.
Project context and objectives:
The main objective of ASPIRATE is to develop an innovative technology for machining CFRP and GFRP parts based on the internal extraction of the produced chip and dust particles through the whole machining system (cutting tool, tool holder, spindle), avoiding all the external devices and suction pumps used nowadays, which reduce the flexibility and leave an unclean part (they do not achieve a complete chip / dust extraction), with the consequent risk for the operator's health and machine components. The basic idea of the project has been conceived by the Spanish machine tool manufacturer ORTZA (this company has left the project in month 21 and it has been replaced by the Spanish SME company EGURKO S. Coop.) to equip their machines with a new technology to solve the problematic machining of fibre-reinforced composites. The three critical components for the success of this development are the hollow cutting tools (to be developed by the SME ZUBIOLA), the diamond coatings for machining abrasive composite materials (to be developed by SME RHO-BEST) and the design of the chip extraction system, which will be developed by RTDs Fraunhofer IST and IDEKO. The SME company INVENT GMBH, as an aerospace end user, will assess and validate the developed technologies in each of the target potential applications and will provide a technology transfer by the end of the project. Spain, Germany and Austria will be represented in the consortium, providing a higher impact of the breakthrough in Europe.
The new chip and dust extraction system is rated to become a breakthrough and a reference for machining companies in search of highly productive and human safe technologies in producing reinforced composite components. The technological advances achieved by the end of this project will lead European countries to the head of world composites machining industry, with a qualitative jump for at least 3 years.
The specific objectives of the project will be the following:
(1) The increase of the machining rates from those currently been used in industry by 25 % due to two main reasons: the air flow through the cutting tool will cool the cutting process (current processes are not cooled) and the application of customised surface coatings to delay cutting edge wear and reduce friction.
(2) Elimination of the 100 % of the dust produced during the machining of CFRP and GFRP from the working area and the shop floor facilities, improving operator's working conditions, prolonging the life of the moving components and thus lowering the production costs.
(3) Development of innovative cutting tools for the machining of composite materials with internal chip extraction possibly creating a new patent.
(4) Development of particular cutting geometry for cutting tools to enhance the application of diamond coatings to enlarge the life of the cutting tools on a 15 % and reduce the generation of heat in the cutting process.
(5) Development of inside coating applications for the hollow system (cutting tool, spindle) based on low-friction and anti-adhesive coatings.
(6) Development of a demonstrator to validate the new internal chip extraction machining technology.
(7) Validation of the achieved results under the industrial requirements and applications set by the end users.
CFRP and GFRP are considered difficult to cut materials due to the same characteristics that grant them with good mechanical properties: not homogeneous, anisotropic, and very abrasive reinforcement fibres. Currently the main problems of the machining of composite materials are the damage of the part (delamination), cracks, bad surface finish, the extreme wear of the cutting tool and the collection / extraction of the small particles of material produced during machining. All these features make composite materials far different from the machining of metals, which both the traditional EU SME machine-tool builders, component manufacturers and end users are used to work with.
The approach of the project is to minimise these problems increasing the machining rates and offering a technological solution based on new developments.
There will be three main research areas for such a goal: first the innovative development of a machine capable of extracting chips and dust particles through the tool and the spindle, second the development of a new generation of hollow cutting tools and third the development of anti-adhesive and wear-resistant coating systems for the tool including diamond coatings with SiC interlayer. Positive results on the proposed research fields, tested on the pre-industrial demonstrator, will help to solve all the problems highlighted above and report a knowledge-based technology to the consortium partners, which will result on a technological advance to those companies from low wage countries.
Project results:
The main objective of ASPIRATE was to develop an innovative technology for machining CFRP and GFRP parts based on the internal extraction of the produced chip and dust particles through the whole machining system (cutting tool, tool holder, spindle), avoiding all the external devices and suction pumps used nowadays, which reduce the flexibility and leave an unclean part (they do not achieve a complete chip/dust extraction), with the consequent risk for the operator's health and machine's components.
The internal chip extraction technology is based on 3 main components:
(1) hollow cutting tools suitable for machining CRFC;
(2) diamond coatings with high abrasion wear resistance;
(3) chip extraction system operating on the machine tool.
The new chip and dust extraction system is rated to become a breakthrough and a reference for machining companies in search of highly productive and human safe technologies in composite parts production. The technological advances achieved by the end of this project will lead European countries to the head of world composites machining industry, with a qualitative jump for at least 3 years.
The specific objectives of the project, as they appeared on the description of work for the activity performed in each of the work packages (WPs), are listed below:
WP1: System identification and working procedure
(1) detailed definition of the requirements of the pilot cases to test using the internal chip extraction technology, different applications and materials;
(2) real-working conditions in terms of productivity, cost effectiveness, quality and accuracy from the end user point of view;
(3) definition of the main features and characteristics of the system, according to the requirements of the end users and targeted materials;
(4) detailed definition of the development and testing procedure to be applied in the different phases of the project, from the preliminary flow analysis to the final implementation of the system in the machine tool;
(5) definition of the environmental and safety aspects to be introduced into the pilot system.
These first activities were accomplished during the first 6 months of the project (from 1 June 2009 to 1 December 2009). During the development of this first group of definition activities, the involvement of the SMEs was crucial, as the system to be developed must fulfil the expectations of the participating SMEs and also should give a cost effective and quality response to the requirements established by the market.
As an example of the activity performed in this WP, the next tables show the process parameter data for different cutting processes defined by AIRBUS for the production of composite components. This information was provided by beneficiary company INVENT GMBH along with the tentative industrial parts to be used for the validation of this innovative cutting process.
WP2: Pilot system development
The objectives defined for this WP were oriented to develop the core elements that will make up the internal chip extraction technology, making it feasible to be applied on industrial scenarios:
- A new electro-spindle able to integrate the internal chip extraction technology. As well as the technological breakthrough for chip extraction, power, stability, rotational speed and accuracy will be key factors for the success of the new spindle.
- The selection and testing of different suction systems will be run in this WP. The variables will be determined and the design of the whole machine system will be realised to maximise the efficiency of the suction system.
- A control system to monitor the chip extraction process preventing chip jam and possible damages in workpiece and tool. This control system must response to any disturbance with an appropriate action.
Once the development of the single elements is made, all of them would be integrated in the pilot system for the final validation of the whole system.
The characteristics of the spindle are summarised next:
(1) Tool holding is by an elastic ER32 collet.
(2) Machining refrigeration: no refrigeration is foreseen as most aerospace companies do not permit cooling in the machining of fibre-reinforced composites.
(3) Power and speed have been established in order to be able to reach the values of cutting parameters, according to cutting speed, feed rate, cutting sections, part material specific cutting forces etc.
(4) Internal spindle bore: An internal bore, diameter 10 mm goes through the spindle. Internal bore has been designed without any direction or section changes in order to facilitate internal air+chip+dust flow.
(5) Stiffness requirements: Elements and materials, alloyed steel with Ni Cr and Mo as main alloy elements, has been selected to stand cutting forces, torque and power, despite the loss of material section due to the internal bore.
(6) Rear end of spindle has been modified, including a 10-degree conical end slope, to better connect it to suction pump by means of a rotary joint.
In order to achieve a cost effective system, by means of low equipment cost, good maintainability, reliability and availability, prototypes based on commercial vacuum pumps have been selected in this WP.
The initially selected vacuum pumps were chosen with the main goal of incorporating the most suitable equipment for the internal chip aspiration process. The main characteristics of prototypes were:
(1) high or lower under pressure values of 0.42 - 0.84 bar;
(2) compact system design or high volume and footprint dimensions of 175 - 80 cm.
In the new control system, aspiration pump is connected to the programmable logic controller (PLC)'s digital input / output module and to computer numerical control (CNC). The CNC can command the aspiration pump as well as the machine tool itself , indeed CNC is always aware of the state of the aspiration pump.
Operator is now able to control the aspiration system in two ways:
(1) Manual mode machine: Operator directly switches on / off the vacuum pump by means of a push located in the machine tool panel control.
(2) Automatic mode: Aspiration system can be activated or deactivated in machining programmes by an auxiliary function M59, for switching on and M60 for switching off.
The task on WP2 finalised with the integration of the complete system: spindle, tool holder, vacuum pump and control system.
After the initial system validation tests, the final pilot system has been used in all machining tests for the ASPIRATE project.
WP3: Cutting tool development
Being the cutting tool one of the most critical technologies to be developed regarding the internal chip aspiration process, the research and development activities in this WP were focused on the following issues:
(a) development of hollow cutting tools for internal chip extraction during machining;
(b) a new cutting tool geometry to enhance the performance of the abrasion protection coatings of the cutting edges. The cutting geometry and the coating should be adapted to the type of fibre of the material and its orientation;
(c) development of anti-adhesive coating for the internal surface of the hollow shaft of the tool based on Ni and Cr layers with PTFE microcapsules.
Several approaches were defined on the design and fabrication of these hollow cutting tools:
(a) adapting and improving steel tube polycrystalline diamond (PCD) teeth internal aspiration tools to reinforced composite materials;
(b) developing a new concept for internal aspiration tools. Solid carbide suitable for internal aspiration machining of composites.
Different tool prototypes have been proved to find the best characteristics for both types of aspiration tools. Finally the optimised prototypes of hollow cutting tools have been designed, produced and tested.
The WP3 has performed also an extensive activity in the research and development of optimum coating materials and technologies to be applied both to the cutting edges, for improving tool life and resistance to wear, as well as for coating the internal bore of the spindle tube, in order to avoid any chips and dust jamming, which could endanger the safety of the process.
Diamond coatings of 8 µm thickness have been deposited onto cemented carbide tools with 0.5 µm SiC interlayer made with silane and methane precursors and with different deposition parameters. Closed diamond films were observed.
WP4: Cutting strategy
The main objective and activities within WP4 were oriented to the development of HSC cutting technology with internal chip evacuation for machining FRP composites. This includes the definition of process parameters matching internal chip removal and dry technology, based on the elaboration of necessary basic knowledge about chip formation, tribological conditions and safety aspects. In that sense, it has been researched how the cutting parameters, cutting tool geometry and cutting strategy affect the quality of the machined part and the wear of the cutting tool.
Further on, the development of advanced machining strategies, e.g. circular milling processes, contouring and five-axis machining, with regard to technological, ecological and cost effectiveness (material removal rate, processing time and cutting tool consumption) has been also core activity of this WP.
WP5: Technology transfer and industrial validation
The objective of this task was the application, at the maximum possible level, of the developed machining system on industrial scenarios.
The validation has been performed on the pilot system set up in IDEKO facilities, but working under the industrial conditions stated by INVENT as the end user. ZUBIOLA did provide the necessary cutting tools for the different industrial applications tests.
The results of this WP has permitted to evaluate the developed technology against the traditional processes under the productive terms (cutting speed, cutting feed, tool life, MRR, accuracy) quantified previously in WP1 by INVENT.
It has been also analysed the operator's health hazards due to the evacuated chips, as well as safety issues regarding machine, part, fixture, cutting tool and process with the new technology.
Potential impact:
Besides the activities on presenting the project results made by the project partners in their own facilities, by means of posters and presentations to customers, the consortium has made several actions for disseminating the project outcomes:
- JEC Fair 2011: During 29 - 31 March 2011, the results obtained on the ASPIRATE project were presented at a Boot on the prestigious JEC Composites fair in Paris. The JEC fair is the most important event related with composites manufacturing held in Europe.
During this fair, many companies interested in our aspiration machining technology came to the boot for requesting information.
- International Innovation Journal: In April 2011 an interview and a description of the main project results were published in a 3 pages report within the April issue of the International Innovation journal. This journal is being distributed to more than 30 000 readers in Europe, the United States of America (USA) and in Japan. Many industrial, European Commission (EC) officers, scientists and academic people receive this journal regularly.
- CFK Stade Valley Convention: ASPIRATE consortium decided to present also the results of the project on the CFK Stade Convention, which was held on 6 - 8 June 2011 at the Stade Convention, a composites centred event celebrated in the city of Stade (Germany).
Regarding the exploitation issues, the consortium has prepared the Plan for Using and Disseminating the Foreground (PUDF) report. In this document they have been identified several potential industrially exploitable results, the markets where these results will be presented, the targeted industrial sectors and the time to market.
Contact details
IDEKO S. COOP.
Coordinator: Joseba Perez Bilbatua
Tel. +34-943-748000
Email: jperez@ideko.es
Researcher: Imanol Ferreres
Tel. +34-943-748000
Email: iferreres@ideko.es
EGURKO S. COOP.
Researcher: Alfonso Casanova
Tel: +34-943-860100
Email: acasanova@egurko.com
ZUBIOLA S. COOP.
Researcher: Rafael Encina
Tel: +34 943 157056
Email: rencina@zubiola.es
Rho-BeSt GmbH
Researcher: Patrick Schrittwieser
Tel. +43-512-28355922
Email: p.schrittwieser@rhobest.com
INVENT GmbH
Researcher: Maik Wonneberger
Tel: + 49-531-2446610
Email: maik.wonneberger@invent-gmbh.de
FRAUNHOFER IST
Researcher: Jan Gäbler
Tel: +49-531-2155625
Email: jan.gaebler@ist.fraunhofer.de
List of websites: http://www.aspirate.eu(se abrirá en una nueva ventana)
The aerospace industry has been the key market for pushing this big leap towards industrial production of fibre reinforced composite components. Nowadays, the development of the production techniques and the reduction on production costs have allow wider applications in emerging markets, such as, wind energy, deep water oil platforms and transportation, as well as in more traditional scenarios like construction and civil structures or sporting goods sector.
Nevertheless, some phases of the composite products production chain present several hazards for the operator's health as well as the environment impact.
The ASPIRATE project, funded by the 'Research for the benefit of SMEs' programme, aims to give and answer to the aforementioned drawbacks, eliminating the dust and chips completely from the working area, without affecting the operator, contributing to the cleanliness of the workpiece and maintaining the maximum flexibility of the process, as no external or peripherals.
The technology resultant from this project is based on the machining with internal chip and dust evacuation, through a hollow tool connected to a standard HSK tool-holder, a modified spindle and a suction pump attached at its rear.
The preliminary tests made on carbon and glass fibre-reinforced plastics (CFRP and GFRP), opened exciting application possibilities. ASPIRATE consortium involves several small and medium-sized enterprises (SMEs) from these sectors, as well as, research and technological development (RTD) actors with the experience and skills for ramping up these developments to real industrial applications.
The industrial consortium is formed by 4 SMEs from 3 European countries. All these SMEs are also intensive in research and development (R&D), as it is the case of INVENT GMBH (Braunschweig, Germany) in the design and development of aerospace components and structural applications in CFRP and GFRP, the company RHO-BEST (Innsbruck, Austria) in the development of advanced coating materials and processes, ORTZA S. Coop. (Huarte, Spain), a machine tool producer SME, with a clear target on the design and building of specialised machines for machining composite materials and finally, ZUBIOLA S. Coop. (Azkoitia, Spain), as manufacturer of special and customised cutting tools.
It is worth to mention that the beneficiary company ORTZA S. Coop. decided to leave the project on February 2011 due to the hard financial conditions this company was suffering due to the economic crisis.
After a validation process made jointly with the REA officers, it was agreed to replace ORTZA S. Coop. company by the Spanish SME company EGURKO S. Coop, which is also focusing its activity on the production of machine tools for the wood sector with high interest on the evolution of its machines to the design and production of machines for the composite industry.
The final entrance of EGURKO S. Coop. to the consortium was effective on 15 February 2011 and it was also stated on the 1st amendment to the contract finally signed by the REA director on May 2011.
The coordinator of the project is IDEKO-IK4, a Spanish research centre specialised on machine tools, production equipment and manufacturing processes, with a comprehensive trajectory on Framework Programme (FP) research activities. The other RTD is the Fraunhofer IST, with large experience also on the participation of European Union (EU)-funded projects.
ASPIRATE project did start on 1 June 2009 and ended on 30 May 2011, so it has lasted a total of 24 months. In this period some key achievements have been obtained, such as the development of a complete system for the machining of CFRP materials extracting the chips and dust through the tool-holder-spindle-pump system, the design, production and testing of hollow cutting tools with brazed diamond coated inserts, as well as the corresponding validation of the system, tools and process parameters over real industrial test cases.
In the first period (month 0 to month 12) the consortium completed the design and implementation of the machine tool, which was ready to accomplish the machining tests. ORT.
Project context and objectives:
The main objective of ASPIRATE is to develop an innovative technology for machining CFRP and GFRP parts based on the internal extraction of the produced chip and dust particles through the whole machining system (cutting tool, tool holder, spindle), avoiding all the external devices and suction pumps used nowadays, which reduce the flexibility and leave an unclean part (they do not achieve a complete chip / dust extraction), with the consequent risk for the operator's health and machine components. The basic idea of the project has been conceived by the Spanish machine tool manufacturer ORTZA (this company has left the project in month 21 and it has been replaced by the Spanish SME company EGURKO S. Coop.) to equip their machines with a new technology to solve the problematic machining of fibre-reinforced composites. The three critical components for the success of this development are the hollow cutting tools (to be developed by the SME ZUBIOLA), the diamond coatings for machining abrasive composite materials (to be developed by SME RHO-BEST) and the design of the chip extraction system, which will be developed by RTDs Fraunhofer IST and IDEKO. The SME company INVENT GMBH, as an aerospace end user, will assess and validate the developed technologies in each of the target potential applications and will provide a technology transfer by the end of the project. Spain, Germany and Austria will be represented in the consortium, providing a higher impact of the breakthrough in Europe.
The new chip and dust extraction system is rated to become a breakthrough and a reference for machining companies in search of highly productive and human safe technologies in producing reinforced composite components. The technological advances achieved by the end of this project will lead European countries to the head of world composites machining industry, with a qualitative jump for at least 3 years.
The specific objectives of the project will be the following:
(1) The increase of the machining rates from those currently been used in industry by 25 % due to two main reasons: the air flow through the cutting tool will cool the cutting process (current processes are not cooled) and the application of customised surface coatings to delay cutting edge wear and reduce friction.
(2) Elimination of the 100 % of the dust produced during the machining of CFRP and GFRP from the working area and the shop floor facilities, improving operator's working conditions, prolonging the life of the moving components and thus lowering the production costs.
(3) Development of innovative cutting tools for the machining of composite materials with internal chip extraction possibly creating a new patent.
(4) Development of particular cutting geometry for cutting tools to enhance the application of diamond coatings to enlarge the life of the cutting tools on a 15 % and reduce the generation of heat in the cutting process.
(5) Development of inside coating applications for the hollow system (cutting tool, spindle) based on low-friction and anti-adhesive coatings.
(6) Development of a demonstrator to validate the new internal chip extraction machining technology.
(7) Validation of the achieved results under the industrial requirements and applications set by the end users.
CFRP and GFRP are considered difficult to cut materials due to the same characteristics that grant them with good mechanical properties: not homogeneous, anisotropic, and very abrasive reinforcement fibres. Currently the main problems of the machining of composite materials are the damage of the part (delamination), cracks, bad surface finish, the extreme wear of the cutting tool and the collection / extraction of the small particles of material produced during machining. All these features make composite materials far different from the machining of metals, which both the traditional EU SME machine-tool builders, component manufacturers and end users are used to work with.
The approach of the project is to minimise these problems increasing the machining rates and offering a technological solution based on new developments.
There will be three main research areas for such a goal: first the innovative development of a machine capable of extracting chips and dust particles through the tool and the spindle, second the development of a new generation of hollow cutting tools and third the development of anti-adhesive and wear-resistant coating systems for the tool including diamond coatings with SiC interlayer. Positive results on the proposed research fields, tested on the pre-industrial demonstrator, will help to solve all the problems highlighted above and report a knowledge-based technology to the consortium partners, which will result on a technological advance to those companies from low wage countries.
Project results:
The main objective of ASPIRATE was to develop an innovative technology for machining CFRP and GFRP parts based on the internal extraction of the produced chip and dust particles through the whole machining system (cutting tool, tool holder, spindle), avoiding all the external devices and suction pumps used nowadays, which reduce the flexibility and leave an unclean part (they do not achieve a complete chip/dust extraction), with the consequent risk for the operator's health and machine's components.
The internal chip extraction technology is based on 3 main components:
(1) hollow cutting tools suitable for machining CRFC;
(2) diamond coatings with high abrasion wear resistance;
(3) chip extraction system operating on the machine tool.
The new chip and dust extraction system is rated to become a breakthrough and a reference for machining companies in search of highly productive and human safe technologies in composite parts production. The technological advances achieved by the end of this project will lead European countries to the head of world composites machining industry, with a qualitative jump for at least 3 years.
The specific objectives of the project, as they appeared on the description of work for the activity performed in each of the work packages (WPs), are listed below:
WP1: System identification and working procedure
(1) detailed definition of the requirements of the pilot cases to test using the internal chip extraction technology, different applications and materials;
(2) real-working conditions in terms of productivity, cost effectiveness, quality and accuracy from the end user point of view;
(3) definition of the main features and characteristics of the system, according to the requirements of the end users and targeted materials;
(4) detailed definition of the development and testing procedure to be applied in the different phases of the project, from the preliminary flow analysis to the final implementation of the system in the machine tool;
(5) definition of the environmental and safety aspects to be introduced into the pilot system.
These first activities were accomplished during the first 6 months of the project (from 1 June 2009 to 1 December 2009). During the development of this first group of definition activities, the involvement of the SMEs was crucial, as the system to be developed must fulfil the expectations of the participating SMEs and also should give a cost effective and quality response to the requirements established by the market.
As an example of the activity performed in this WP, the next tables show the process parameter data for different cutting processes defined by AIRBUS for the production of composite components. This information was provided by beneficiary company INVENT GMBH along with the tentative industrial parts to be used for the validation of this innovative cutting process.
WP2: Pilot system development
The objectives defined for this WP were oriented to develop the core elements that will make up the internal chip extraction technology, making it feasible to be applied on industrial scenarios:
- A new electro-spindle able to integrate the internal chip extraction technology. As well as the technological breakthrough for chip extraction, power, stability, rotational speed and accuracy will be key factors for the success of the new spindle.
- The selection and testing of different suction systems will be run in this WP. The variables will be determined and the design of the whole machine system will be realised to maximise the efficiency of the suction system.
- A control system to monitor the chip extraction process preventing chip jam and possible damages in workpiece and tool. This control system must response to any disturbance with an appropriate action.
Once the development of the single elements is made, all of them would be integrated in the pilot system for the final validation of the whole system.
The characteristics of the spindle are summarised next:
(1) Tool holding is by an elastic ER32 collet.
(2) Machining refrigeration: no refrigeration is foreseen as most aerospace companies do not permit cooling in the machining of fibre-reinforced composites.
(3) Power and speed have been established in order to be able to reach the values of cutting parameters, according to cutting speed, feed rate, cutting sections, part material specific cutting forces etc.
(4) Internal spindle bore: An internal bore, diameter 10 mm goes through the spindle. Internal bore has been designed without any direction or section changes in order to facilitate internal air+chip+dust flow.
(5) Stiffness requirements: Elements and materials, alloyed steel with Ni Cr and Mo as main alloy elements, has been selected to stand cutting forces, torque and power, despite the loss of material section due to the internal bore.
(6) Rear end of spindle has been modified, including a 10-degree conical end slope, to better connect it to suction pump by means of a rotary joint.
In order to achieve a cost effective system, by means of low equipment cost, good maintainability, reliability and availability, prototypes based on commercial vacuum pumps have been selected in this WP.
The initially selected vacuum pumps were chosen with the main goal of incorporating the most suitable equipment for the internal chip aspiration process. The main characteristics of prototypes were:
(1) high or lower under pressure values of 0.42 - 0.84 bar;
(2) compact system design or high volume and footprint dimensions of 175 - 80 cm.
In the new control system, aspiration pump is connected to the programmable logic controller (PLC)'s digital input / output module and to computer numerical control (CNC). The CNC can command the aspiration pump as well as the machine tool itself , indeed CNC is always aware of the state of the aspiration pump.
Operator is now able to control the aspiration system in two ways:
(1) Manual mode machine: Operator directly switches on / off the vacuum pump by means of a push located in the machine tool panel control.
(2) Automatic mode: Aspiration system can be activated or deactivated in machining programmes by an auxiliary function M59, for switching on and M60 for switching off.
The task on WP2 finalised with the integration of the complete system: spindle, tool holder, vacuum pump and control system.
After the initial system validation tests, the final pilot system has been used in all machining tests for the ASPIRATE project.
WP3: Cutting tool development
Being the cutting tool one of the most critical technologies to be developed regarding the internal chip aspiration process, the research and development activities in this WP were focused on the following issues:
(a) development of hollow cutting tools for internal chip extraction during machining;
(b) a new cutting tool geometry to enhance the performance of the abrasion protection coatings of the cutting edges. The cutting geometry and the coating should be adapted to the type of fibre of the material and its orientation;
(c) development of anti-adhesive coating for the internal surface of the hollow shaft of the tool based on Ni and Cr layers with PTFE microcapsules.
Several approaches were defined on the design and fabrication of these hollow cutting tools:
(a) adapting and improving steel tube polycrystalline diamond (PCD) teeth internal aspiration tools to reinforced composite materials;
(b) developing a new concept for internal aspiration tools. Solid carbide suitable for internal aspiration machining of composites.
Different tool prototypes have been proved to find the best characteristics for both types of aspiration tools. Finally the optimised prototypes of hollow cutting tools have been designed, produced and tested.
The WP3 has performed also an extensive activity in the research and development of optimum coating materials and technologies to be applied both to the cutting edges, for improving tool life and resistance to wear, as well as for coating the internal bore of the spindle tube, in order to avoid any chips and dust jamming, which could endanger the safety of the process.
Diamond coatings of 8 µm thickness have been deposited onto cemented carbide tools with 0.5 µm SiC interlayer made with silane and methane precursors and with different deposition parameters. Closed diamond films were observed.
WP4: Cutting strategy
The main objective and activities within WP4 were oriented to the development of HSC cutting technology with internal chip evacuation for machining FRP composites. This includes the definition of process parameters matching internal chip removal and dry technology, based on the elaboration of necessary basic knowledge about chip formation, tribological conditions and safety aspects. In that sense, it has been researched how the cutting parameters, cutting tool geometry and cutting strategy affect the quality of the machined part and the wear of the cutting tool.
Further on, the development of advanced machining strategies, e.g. circular milling processes, contouring and five-axis machining, with regard to technological, ecological and cost effectiveness (material removal rate, processing time and cutting tool consumption) has been also core activity of this WP.
WP5: Technology transfer and industrial validation
The objective of this task was the application, at the maximum possible level, of the developed machining system on industrial scenarios.
The validation has been performed on the pilot system set up in IDEKO facilities, but working under the industrial conditions stated by INVENT as the end user. ZUBIOLA did provide the necessary cutting tools for the different industrial applications tests.
The results of this WP has permitted to evaluate the developed technology against the traditional processes under the productive terms (cutting speed, cutting feed, tool life, MRR, accuracy) quantified previously in WP1 by INVENT.
It has been also analysed the operator's health hazards due to the evacuated chips, as well as safety issues regarding machine, part, fixture, cutting tool and process with the new technology.
Potential impact:
Besides the activities on presenting the project results made by the project partners in their own facilities, by means of posters and presentations to customers, the consortium has made several actions for disseminating the project outcomes:
- JEC Fair 2011: During 29 - 31 March 2011, the results obtained on the ASPIRATE project were presented at a Boot on the prestigious JEC Composites fair in Paris. The JEC fair is the most important event related with composites manufacturing held in Europe.
During this fair, many companies interested in our aspiration machining technology came to the boot for requesting information.
- International Innovation Journal: In April 2011 an interview and a description of the main project results were published in a 3 pages report within the April issue of the International Innovation journal. This journal is being distributed to more than 30 000 readers in Europe, the United States of America (USA) and in Japan. Many industrial, European Commission (EC) officers, scientists and academic people receive this journal regularly.
- CFK Stade Valley Convention: ASPIRATE consortium decided to present also the results of the project on the CFK Stade Convention, which was held on 6 - 8 June 2011 at the Stade Convention, a composites centred event celebrated in the city of Stade (Germany).
Regarding the exploitation issues, the consortium has prepared the Plan for Using and Disseminating the Foreground (PUDF) report. In this document they have been identified several potential industrially exploitable results, the markets where these results will be presented, the targeted industrial sectors and the time to market.
Contact details
IDEKO S. COOP.
Coordinator: Joseba Perez Bilbatua
Tel. +34-943-748000
Email: jperez@ideko.es
Researcher: Imanol Ferreres
Tel. +34-943-748000
Email: iferreres@ideko.es
EGURKO S. COOP.
Researcher: Alfonso Casanova
Tel: +34-943-860100
Email: acasanova@egurko.com
ZUBIOLA S. COOP.
Researcher: Rafael Encina
Tel: +34 943 157056
Email: rencina@zubiola.es
Rho-BeSt GmbH
Researcher: Patrick Schrittwieser
Tel. +43-512-28355922
Email: p.schrittwieser@rhobest.com
INVENT GmbH
Researcher: Maik Wonneberger
Tel: + 49-531-2446610
Email: maik.wonneberger@invent-gmbh.de
FRAUNHOFER IST
Researcher: Jan Gäbler
Tel: +49-531-2155625
Email: jan.gaebler@ist.fraunhofer.de
List of websites: http://www.aspirate.eu(se abrirá en una nueva ventana)
