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Intelligent Manufacture from Powder by Advanced Laser Assimilation

Final Report Summary - IMPALA (Intelligent manufacture from powder by advanced laser assimilation)

IMPALA is a collaboration between European Union (EU) companies and research organisations with the objective of developing flexible and efficient rapid manufacturing processes of custom parts or small batches. The concept of intelligent manufacture from powder by advanced laser assimilation (IMPALA) is to develop a flexible and efficient rapid manufacturing process that is powder-based and uses laser technology to produce customised, small-to-medium volume parts, with features as small as 20 µm.

IMPALA's overall aims and objectives for the project duration were customisation, miniaturisation and cycle-time, in addition to demonstrating the viability of laser additive manufacturing process (LAMP) to achieve significant benefits over conventional manufacturing methods across a number of industry sectors within Europe and the wider economic area.

Customisation was achieved through the Wisildent dental bridge application, this allowed patient CT data to be used to produce individual customised parts. Multiple (up to 10) individual implants can be produced in one build using powder bed lamp processing.

Work to achieve the miniaturisation objective was carried out for both the blown powder technology and powder bed techniques. It was noted through the project that 20 µm feature size would be very challenging to achieve. For the blown powder, technology miniature nozzles were designed and manufactured by IWS and several demonstrator components were built. A cube 0.5 x 0.5 x 0.5mm in size was built with a single track deposit of below 100 µm. A miniature pyramid was also produced using the nozzle, shows the pyramid, which measured 0.5 x 0.5 x 1.0 mm. For the powder bed technology the WP 6 'fallback demonstrator' showed that consistent miniature feature size for the equipment was 0.1 mm.

There were three clear demonstrators of where the objective of cycle time has been achieved in the IMPALA project. The first example is for the OSVAT valve seat cladding. When compared to the conventional plasma arc deposition it was found that the laser deposition process was much improved and offered a cycle time of approximately 25 seconds and a near net shape deposit, minimising post processing efforts, this correlates to approximate 20 % saving in cost per part.

The second example was the Wisildent dental bridge where currently the components are handmade and finished taking up to two days and very labour intensive. However, using laser powder bed technology the cycle time can be reduced to 30 minutes per part. A final finishing step is still required to achieve the surface finish requirements.

The final example was the IMPALA demonstrator component; the metal leading edge (MLE), the component when produced using laser processing and final milling can significantly reduce cycle time, material waste and up to a 50 % cost reduction.

The project had two demonstrations of complete IMPALA systems producing the chosen project demonstrators. One system focused on the blown powder technology and was based at GE in Turkey and the other focused on the powder bed technology and was based at TWI in the United Kingdom (UK).

These systems demonstrated all the developments delivered by the project including the digital interface, the toolpath generator, simulation interface results and monitoring system. The impact on the production of the demonstrators compared with conventional manufacture was assessed. A project video was produced by the consortium and can be viewed on the IMPALA website (please see http://www.impala-project.eu.com onsite).

Within the project all the end users have been exposed to new innovative technologies and the project has focused on applying the advancements of these technologies to industrial applications that the end users would directly benefit from.

Project context and objectives:

The concept of IMPALA was to develop a flexible and efficient rapid manufacturing process that was powder-based and applied laser technology to produce customised and small-to-medium volume parts, aiming to produce features as small as 20 µm.

IMPALA's overall aims and objectives for the project duration were customisation, miniaturisation and cycle-time, in addition to demonstrating the viability of LAMP to achieve significant benefits over conventional manufacturing methods across a number of industrial sectors within Europe and the wider economic area.

There are many different additive manufacturing/prototyping techniques available; however the IMPALA project focused on the two techniques of laser powder bed and laser blown powder deposition. These two techniques show the most potential for LAMP, allowing more complex geometries or advanced product functionality, or allowing entirely new product designs, currently not possible to manufacture using conventional processes, such as casting and machining.

The laser powder deposition using a nozzle concept uses a blown-powder approach to deposit in-process. The powder, transported into the laser beam via an inert gas carrier, is focused into a small area in the vicinity of the laser beam focus using a specially designed nozzle, and melted above or on the material substrate.

The laser powder bed technique operates by scanning a focused laser beam across a bed of powder, locally fusing the powder in a pre-determined pattern. Upon completion of the first scan, a new layer of powder is applied on top of it and the process is repeated. These steps are repeated, building up the part layer-by-layer.

The project had two demonstration activities of complete IMPALA systems producing the chosen project demonstrators. One system focused on the blown powder technology and was based at GE in Turkey and the other focused on the powder bed technology and was based at TWI in the UK.

The intention of the IMPALA systems was to integrate the developed LAMP technologies from the project into two existing laser additive manufacturing (LAM) systems within the consortium to demonstrate improved capability and to produce the selected IMPALA demonstrators. These systems demonstrated all the developments that had taken place across the project including the digital interface, the toolpath generator, simulation interface results and monitoring system. The impact on the production of the demonstrators compared with conventional manufacture was assessed.

The aim of the developments within the project was to focus on end user applications and their needs to take steps towards adopting such advanced manufacturing technologies. Each end-user within the consortium put forward potential applications for using LAMP. Each of these applications became the focus of the process development throughout the project with two demonstrators being selected to show or illustrate the developments of the IMPALA project by means of a component manufactured using IMPALA technology.

The two components selected to be the IMPALA demonstrators were a chassis for a Cochlear hearing implant for cochlear, using powder bed laser technology, and the metal leading edge (MLE) for GE Aviation, using blown powder laser technology.

The implant chassis from Cochlear was chosen as a demonstrator, because it integrated miniaturisation, customisation (in the product development phase) and manufacturing cycle-time reduction.

There were also crossover benefits by selecting this application, because there were some developments needed to take place for this demonstrator to be produced successfully which were also required for other end user applications therefore benefitting other partners within the consortium. The high dimensional precision (Micronorma), the material (Wisildent) and the reliability of the process (General Electric) are some examples.

An economic assessment was carried out to assess the validity in producing the chassis with powder bed laser technology. The conclusion of the economic study was that powder bed technology is a cost effective process that can reduce the cost per part by 42 % compare to the currently used manufacturing process of milling. Considering a volume of 30 000 parts produced part per year, EUR 741 000 could be saved annually. Other positive conclusions can be considered like the reduced lead time and the flexibility on the design modification of the parts.

Regarding the blown powder process, the MLE from General Electric was selected because of its design complexity, miniaturisation of the wall thickness and cycle-time / cost reduction. The material saving in this application has also been considered (Ti-6Al-4V).

The economic assessment was focussed on comparison with milling (the current conventional method of manufacture) and the use of blown powder laser technology with a fine milling finishing process. It was concluded that there is a strong economic argument for creating the MLE using blown powder deposition as it was predicted that an overall saving of approximately EUR 296 million (USD 380 million) could be achieved. Additional advantages of using LMAP technology for the MLE production include:
- reduction in the cycle-time;
- avoidance of vacuum furnace brazing;
- reduction in the part counts; and
- reduction in material waste.

Project results:

The technical approach of the project was to divide the project into eight work packages (WPs). The project started with a detailed specification of the products / applications that the IMPALA end users wished to produce with the developed IMPALA technologies - WP 1. These industrial requirements were then translated into technological developments on four distinct levels:
- powder manufacture - WP 2;
- software development - WP 3;
- powder bed and powder deposition equipment - WP 4; and
- process development - WP5.

In the final stages of the project, the developed technologies were integrated in order to demonstrate their capability and delivery of the three main objectives, customisation, miniaturisation and reduced cycle-time (WP 6). The final two work packages comprised of project management (WP 7) and exploitation and dissemination of the created foreground (WP 8).

An evaluation of the IMPALA project results as a whole was carried out by the consortium assessing each result in terms of meeting the IMPALA objectives, generating IP and the benefits to partners within the project. The IMPALA project results are listed below:
1. Aluminium alloy: Development and processing
2. Production of fine titanium powders
3. Ceramic and glass powder: Development and processing
4. Monitoring system for powder bed process
5. Monitoring system for blown powder deposition
6. Nozzle improvements
7. SLM powder feeder
8. Microcladding system
9. Digital interface
10. LAMP library
11. ToolPath generator
12. DLMD for engine valves
13. Ball on plate application
14. Dental bridge manufacture
15. Combustor component
16. Mining disk manufacture
17. Forming press manufacture
18. Metal leading edge
19. Chassis.

The results were direct outputs from the technical work packages, WP 2 - WP 6. A summary of the work carried out in each WP and details regarding the results are presented in the following sections.

WP 1 - IMPALA specification

Within WP 1, tasks 1.1 and 1.2 consisted mainly of paper-based studies and discussion with the end users. The aim was to establish the industrial requirements of the end users, define the methodology for the development of the IMPALA technologies and to outline an exploitation strategy for the project results. Within the first six months of the project the end-users provided product specifications for each of the products / demonstrators they would like to benefit from the research within the IMPALA project. The following objectives of the work package were:
- to finalise the specification of the IMPALA technologies to be developed;
- to finalise the methodology to be followed for the development of the IMPALA technologies;
- to define the consortium strategy regarding exploitation of the project results.

At the sixth month, meeting of the project and following a technical meeting between the research and technological development (RTD) partners and service providers earlier in the project, the consortium reviewed provided product specifications from the point of view of process developments. 16 applications were put forward for consideration within the project, some products / applications were viewed as straightforward (and could be done with current equipment at one or more of the partners), whereas others would require some process development work, with a selection of them requiring substantial improvements of the technology. Four of the applications suggested by the end users were considered not suitable for LAM, from the point of view of technical and/or economical viability.

The end result of the sixth month meeting was a product summary table, reviewing each of the products from the viewpoint of the LAM process, and the requirements for process development. This table formed the basis of the research strategy and specification for the project, more detail and the table itself can be found in IMPALA deliverable report D1.1.

Whilst predominately the applications table and the developments were to take place in WP 5, the implementation of each application required developments within the remaining work packages for successful completion of the project.

WP 2 - Powder development and characterisation

WP 2 focused on powder development and characterisation for LAM processes. This WP had three objectives:
- to develop metallic powders suitable for LAMP processes at micro-scale;
- to identify suppliers for ceramic and polymer powders;
- to characterise the materials selected for laser absorption.

All deliverables in this WP were completed by the relevant partners and submitted to the European Commission (EC) deliverable D2.2 along with a report on the development of ceramic feedstock powder.

Within WP2 three IMPALA project results were produced:
1. Aluminium alloy: Development and processing
2. Production of fine titanium powders
3. Ceramic and glass powder: Development and processing.

For each project result, an assessment of the novelty of the results, progress beyond the state of the art, benefits to partners and how it assisted with the objectives of the project was performed.

Aluminium alloy development

Alloy powders based on aluminium, nickel and titanium were produced and their physical and chemical characteristics measured. Sample powder materials were supplied by CERAM and TLS for laser trials at the RTO'S TWI, ILT and SME Polyshape.

Work carried out on the aluminium alloys investigated the build-up characteristics of four identified alloys with the aim to focus on one (most suitable for the technology) alloy towards the end of the project. The alloy composition was: Al, 12.07 wt% Si, 0.25wt% Fe, which was found to be best suited for laser processing than other compositions trialled.

Fine (sub-20µm) Ti powder

The production and separation of fine Ti powder with a d50 of 10 µm was successfully carried out and provides the basis for a commercial process. The main equipment used for finer powder production was an EIGA atomiser was used.

Optimisation of the gas nozzle for the atomisation process was investigated, this was to attempt to increase the yield of fine powder. The gas atomisation process for titanium powder is based on a free fall atomisation. That means the melt stream has no contact with any guide system which could regulate the melt flow to the gas nozzle. Therefore the melt flow rate in combination with the gas nozzle arrangement was investigated. A new gas nozzle with optimised gas flow was installed in the atomiser. After the start-up of the new equipment the following improvement was achieved.

The powder yield < 45 µm was significant higher. Whereas the other powder characteristics like flowability and apparent density were worse. This is an indication of the higher fine powder fraction in the raw powder when the new nozzle arrangement is used.

To improve the powder porosity further work is necessary to achieve the target particle size distribution. The selected way of atomising into a pressure reduced spray chamber is possible (in principle) and opens further options to improve the quality of the gas-atomised powder.

A fine Ti-6Al-4V powder was produced with a d50 of 6.4 µm and d90 of 12.0 µm and was tested on equipment at TWI, issues with the handling of flow-ability of such powder made this very difficult to process. Numerous steps within WP 3 were taken to develop a powder feeder for the delivery of fine powder on an SLM machine.

Ceramic powder development

Candidate ceramic powders were identified and trials were carried out on the ceramic powders and laser absorption characteristics have been measured for a number of materials. The study of ceramic powders investigated the interaction between a laser beam source and a range of alumina powders (treated and non-treated, with binders and with no binders) to establish the suitability of the laser technology for production of ceramic three-dimensional (3D) parts starting from a powder system providing a new way to rapidly manufacture precision products from ceramics. A layer-by-layer powder bed approach was used to build-up 3D parts, widening the range of materials that can be used in additive manufacturing.

A method of granulation of fine ceramic powders is needed to provide alumina powders with acceptable flow properties for additive manufacturing. Freeze granulation with a binder addition is a workable solution. From the laser trials samples produced from freeze granulated alumina powder containing silica binder gave the best results as:
- crack-free samples were produced;
- flowability of powder improved and this facilitated setup of the ceramic powder layer;
- if compared with the freeze granulated powders containing the organic binders PVA and PVG, no thermal degradation occurred in the processed sample.

Trials on pure alumina samples indicate that preheating is needed to promote fusion under laser processing.

Laser processing of ceramic powders to produce tailored 3D parts is believed to be an attractive area for industry. Further development work in this area is highly recommended as it is likely to introduce an alternative novel manufacturing technology to make ceramic parts.

Additive manufacturing techniques offer the potential to introduce flexibility to the production of ceramic items by eliminating the need for tooling. The work was directed towards exploitation into industrial sectors including, medical, where this research could potentially offer new ways to manufacture dental and orthopaedic products. Although alumina has been chosen for the initial study, the technique is expected to be equally applicable to a range of other technical ceramics, providing a new way to rapidly manufacture precision products from ceramics.

WP 3 - Process equipment development

The aim of WP 3 was to carry out the development of the process equipment in order for the IMPALA objectives to be achieved. The specific WP objectives were:
- development of laser and optical systems to minimise laser spot and optimise the energy distribution of the laser beam;
- the development of a powder handling system for small dimension powders;
- the development of a real time online monitoring and control system.

All deliverables in this WP were completed by the relevant partners and submitted to the EC with deliverable D3.3 being completed in this final period. Within WP 3 the following IMPALA results were produced:
1. assessment of monitoring system for powder bed process;
2. monitoring system for blown powder deposition;
3. nozzle improvements;
4. SLM powder feeder;
5. microcladding system.

For each project result an assessment of the novelty of the results, progress beyond the state of the art, benefits to partners and how it assisted with the objectives of the project was made. Further detail regarding the results can be found below.

SLM powder feeder

Micronorma and TWI worked on the development of a new powder feeder for the powder bed process. The aim was to enable the successful deposition of finer Ti powders produced in WP2 through the SLM system at TWI.

The powder feeder was tested with standard about 45 µm powder and was found to flow well, however when tested with finer powder the powder feeder became clogged up and the powder would not flow from the hopper. Next steps to improve this included an assessment of vibratory motion to help to agitate the powder and the improved design of the stirring mechanism with the powder feeder.

Finally, investigations were made into the use of a de-ionizer for the powder prior to being fed into the SLM powder feeder.

The conclusions drawn from the results of the experiment were:

- the powder particles have increased flowability when an ioniser is used;
- the interaction between the powder and the dispenser walls is better after deionization of powder;
- the final dispenser has better performance in comparison to the PETG one in terms of dropped powder into the hole. This can be explained by the introduction of the eccentric shafts in the aluminum dispenser. This can be also verified when the ioniser is integrated;
- with the ioniser introduction the flow time was reduced because the ionized air flow forced the powder to drop faster into the bottom of the dispenser.

Monitoring system for blown powder deposition

The development of MOC system is based on the coaxial process control (CPC) system developed at the Fraunhofer ILT/LLT. The CPC system consists of a high speed camera, modular imaging optics and a process computer for image analysis. The system can be used to integrate and investigate various sensors and monitoring and lighting concepts. An important advantage for laser processes is the coaxial layout relative to the laser beam guidance that does not create an additional source of interference.

The monitoring system has been adapted and applied to the powder-fusion process. After defining the requirements for the monitoring system, several sensors, monitoring- and illumination-strategies have been compared in a fundamental research. As a result, the monitoring system described below has been setup. This system has the task to measure the geometry of the melt pool. During the tests, process parameters have been varied to achieve different processing results, representing acceptable and unacceptable deposits, with the camera images analysed for each. The primary goal of this development is to distinguish between acceptable and unacceptable powder fusion conditions, in order to identify imperfections and poor quality of the produced part.

The high-power-LED's illuminate the melt pool at a wavelength of 523 nm. To put the monitoring concept into effect a lot of illumination power is necessary. Therefore the light of the LED's is focused by special designed aspheric lenses to be bright enough for outshining the emission of the process by this specific wavelength. A second action for this aim is the setup of a system for pulsing the LED's.

Thus more illumination power can be used for exposing the camera. By synchronisation the LED's are cooling down while the read-out-time of the camera. The usage of a filter that is just transmissive for the illumination wavelength allows the camera to get a view to the surface of the melt pool and the work piece without disturbances of the process emissions. In the recorded video sequences the boundary between the liquid and the solid phase is visible. To measure the position of this boundary is the task of the image processing algorithms.

Being able to measure this boundary means to measure the geometry of the melt pool. To reach this aim one of the key algorithms is the block-matching-algorithm. The block-matching-algorithm calculates the direction of the motion and the velocity for defined areas of an image in an images sequence.

After a phase of fundamental research for monitoring the blown powder deposition a demonstrator system has been demonstrated at Fraunhofer ILT at the month 36 meeting. In a next step, the monitoring system has been adapted to the demonstrator system at GE in Turkey and monitored the welding of the metal leading edge at the month 42 meeting. The combination of the illumination strategy and the developed algorithms leads to a robust measuring procedure of the melt pool geometry. The algorithms are independent of intensity and thresholds, which is a significant advantage for the comparison of monitored signals. The melt pool geometry is a significant process parameter for the heat dissipation in the work piece. An accuracy of 100 µm and a strong correlation between the monitored signals and the processing results has been demonstrated.

Nozzle improvements

IWS have been mainly focusing their effort on developing the equipment for the powder delivery. This has included looking into the nozzle and assessing new system components in order to enable advanced structures to be produced using laser deposition. Therefore, tasks such as the development of new powder nozzle components and powder delivery, testing of new constructions and characterisation of it have to be undertaken. TWI has been assisting with the nozzle modelling for the powder flow and delivery system and initial results are showing promise. IWS have been working on a new improved coaxial nozzle design achieving a powder focus down to 700 µm.

Compared with conventional powder nozzle the key characteristics of the improved nozzle are:
- turbulence chamber 166 % higher and 46 % thinner;
- width of ring slit reduced by 80 %;
- 15 mm increased length of nozzle tip;
- working distance: 7.5 mm;
- powder inlets are aligned by tubes;
- exact centring of inner and outer nozzle tip.

Trials have been carried out at IWS with the nozzle being fitted onto a cladding system which included brilliant laser source and modified powder feeder. It was found that a cube of 0.5 x 0.5 x 0.5 mm could be produced with a single track of below 100 µm and a pyramid of 0.5 x 0.5 x 1 mm.

This work demonstrates MS5 has been achieved within the project.

TWI carried out work on improving nozzle design with the application of computational fluid dynamics (CFD) for the blown powder processing. Three-dimensional (3D) CFD simulations were completed and it was found that the powder focus diameters was twice as large as axisymmetric two-dimensional (2D)-model, the powder focus standoff distance was smaller than axisymmetric 2D-model and titanium 50 micron diameter spherical particles were used.

In order to validate the CFD simulation, three nozzles with 0.5 0.75 and 1.0 mm annulus gap were manufactured. Powder size of 15 to 45 microns was used with a variety of processing parameters for the experimental trials.

The results showed that powder focus from a coaxial nozzle is largely influenced by (in order of importance):
- nozzle angle;
- the powder diameter and surface area;
- nozzle annulus gap size;
- ratio between carrier and nozzle gas mass flow rate;
- nozzle surface roughness;
- powder mass flow rate.

An increase in the standoff distance is achieved with an increase in the central nozzle gas flow rate, but at the expense of powder focus. A smaller annulus gap and a higher carrier gas flow rate results in turbulent flow conditions which affects the focusing capability. For a smaller powder focus diameter, turbulence in the gas stream must be minimised and spherical, smaller diameter particles must be used.

WP 4 - Software development and integration

The aim of WP 4 was to carry out software development and integration for the IMPALA project with specific objectives looking at the following developments:
- to develop the digital interface that will allow effective communication and exchange of information between the individual IMPALA components;
- to develop a generic tool-path generator, describing the movement of the process head, in NC code, based on a 3D product computer-aided design (CAD) model;
- to develop a digitisation approach, allowing fast and accurate 3D scanning of existing component;
- to integrate the developed technologies in the IMPALA hardware.

All deliverables from WP 4 were completed within the project timescales. The following IMPALA results were generated from WP4:
1. digital interface;
2. LAMP library;
3. ToolPath generator.

For each project result, an assessment of the novelty of the results, progress beyond the state of the art, benefits to partners and how it assisted with the objectives of the project was made. Further detail regarding the results can be found below.

Digital interface

The digital interface (DI) of IMPALA realises the cooperation / integration of the IMPALA related developments to build the IMPALA system and achieve the project objectives. Simply speaking, the task of the DI is to provide the single process steps with the information they need to carry out the predefined tasks. Information in this case may be CAD models used as input for the NC path generation system as well as process parameters such as temperature or speed for the LAMP processing of specific materials. It is also worth noting that the DI needs to take into consideration that the equipment used in the project are based at different facilities within Europe.

BCT will act as an administrator for the DI and the partners will have access to the information. Partners have populated the DI with information such as processing parameters, CAD and other necessary data. The DI is complete and was demonstrated at the month 36 meeting and as an integrated part of the IMPALA SLM system at the month 48 meeting at TWI.

The LMAP library took the results and developments from WP 5 and incorporated them into the DI for the IMPALA consortium to use.

Toolpath generator

Work for the toolpath generator has been carried out in two parts, one looking into five axis NC path programming for multi-axis robots and the other looking into NC laser path adaptation. NC laser toolpath generation is based on CAD data and scanning data, and could be used for new part manufacture or to repair existing components using the IMPALA technologies. The work on NC path generation has been carried out by Norcam. They have focused on the development of five-axis NC path programming of multi-axis robots and this has involved the import and slicing of STL-representation of part geometry, designing and creating an advanced user interface for easier operation and then linked to the five-axis tool path simulation. Within this reporting period NORCAM have completed the toolpath generator and have developed it for a Motorman robot which GE have at their facility and will be used for the IMPALA system 2.

Full details of the toolpath generator can be found in deliverable report D4.2 on the IMPALA website and has been submitted to the EC.

WP 5 - Process development, integration and testing

The overall aim of WP5 was to carry out process development and testing for the IMPALA technologies and systems. The main objectives of the WP were to:
- test, evaluate and compare build-up strategies in terms of productivity, material use efficiency, dimensional accuracy, surface finish, defects and materials properties, and to develop new build-up strategies whenever existing approaches are insufficient;
- to optimise build-up strategies for individual parts, in order to achieve the best dimensional accuracy, surface finish and material properties, compatible with user requirements.

All deliverables for WP 5 were completed and submitted to the EC, the main focus of this work package was the development of end user applications (D5.4) for the consortium partners. However, reports were also produced for the round tobin experiments (D5.3) the LAMP database (D5.1) and the effects of laser re-melting (D5.2). The following IMPALA results were generated:
1. laser blown powder deposition for engine valves
2. ball on plate application
3. dental bridge manufacture
4. combustor component
5. mining disk manufacture
6. forming press manufacture.

For each project result, an assessment of the novelty of the results, progress beyond the state of the art, benefits to partners and how it assisted with the objectives of the project was made.

OSVAT valve

For DLMD for engine valves the end-user was OSVAT working with TWI work was carried out to apply laser deposition techniques to engine valve cladding focussing on the IMPALA objectives of increased cycle time by applying near-net shape deposition into a pre-machined valve groove. The work carried out included the use of high power diffractive optics to tailor the laser beam energy distribution for optimum deposition of the valve.

As a result of this work, TWI has advanced its expertise in the use of high power diffractive optics for laser materials processing and OSVAT has gained experience and test results regarding the capability of laser deposition as an alternative to plasma arc deposition onto engine valves.

Cochlear ball on plate

The SLM process has been used to produce the ball on plate assembly for a Cochlear implant. The ball on plate assembly was an ideal candidate for SLM, because the conventional way to produce the component is a three step manufacturing process however using SLM this could be reduced into one. The benefits of using this technology include reduction in time and cost, ability to implement new designs quickly and the demonstration of additive manufacturing techniques for the production of high value components.

Wisildent dental bridge

Wisildent put forward a dental bridge application for development within WP 5; the aim was to use powder bed-based technology to produce customised individual dental implants. The goal was to reduce time of manufacture to 30 minutes whilst achieving dimensional tolerances and mechanical properties of the material. The material used was biocompatible titanium grade 2 powder. Two powder bed systems were utilised; a Trumaform DLF 250 system and a Realizer 100 SLM system, powder developments for titanium grade 2 to ensure high quality material has been obtained. The results showed that the cycle time could be reduced from 2 days to 30 minutes / part using a more automated production technique without any detriment to the material quality.

GE combustor component

GE Aviation wanted to assess the feasibility of using laser additive manufacturing as a potential production route for a combustor component as shown in Figure 27. The component has complex geometry and internal channels. The material for this part was Inconel 625, optimised parameters were developed for the component, a final finishing was required in order to achieve the required surface finish.

Wolframcarb mining disk

Wolframcarb put forward the application for the production of wear protective coatings (tungsten carbides) on mining components on plane substrates. Trials have been carried out with different ratios of binder material (Deloro 22) and tungsten carbides, investigation has taken place in order to assess the right tool path for a suitable final contour, first trials on test specimen (mining disc) and a mining disc (50 % WC) were returned to Wolframcarb for analysis and testing.

The results of the work showed that hard faced mining discs were tested by rolling test and offered a high resistance in case of high WC contents. Process parameters for the laser cladding process were optimised and, hence, crack free coatings with high WC content could be reached.

Micronorma press

Micronorma put forward applications investigating the use of laser additive technology for forming press manufacture and repair. The geometry of tools and dies has become more complex in recent times. The manufacturing of tools and dies is time consuming and often difficult. Application of laser-based additive manufacturing processes with blown powder has potential to build-up details and small geometries precisely in a short cycle-time, reducing time to market. The process can also be used for customised tools and dies.

IWS applied a blown powder laser technique with continuous coaxial powder supply with the processing head being integrated in a 5-axis-CNC- milling machine with a positioning accuracy of 0.01 mm. The machine is equipped with a 1.5 kW diode laser. Optimised strategies were developed to build-up near net shape customised tools with low surface roughness and minimal distortion. Sample geometries including well-chosen problems encountered in real parts were successfully manufactured with the laser-based blown powder process.

WP 6 - Technology demonstration

WP 6 focused on the demonstration of the technologies developed in the other work packages, the main objective was to produce demonstrators for two industry sectors (medical, aerospace and / or micro-mechanics) and assess the technical and economic advantages of using LAMP processes.

All deliverables were completed and submitted to the EC and the following IMPALA results were generated from this WP:
1. GE MLE;
2. CTC Chassis.

For each project result, an assessment of the novelty of the results, progress beyond the state of the art, benefits to partners and how it assisted with the objectives of the project was made. Further detail regarding the results can be found below.

The demonstrators selected for the project were the Cochlear Chassis and the GE MLE. Working alongside the activity on the demonstrators was the plan to integrate the IMPALA systems and link together the production of the demonstrators with the developments of the system. One system focused on the blown powder technology and was based at GE in Turkey and the other focused on the powder bed technology and was based at TWI in the UK.

The intention of the IMPALA systems was to integrate the developed LAMP technologies from the project into two existing LAM systems within the consortium to demonstrate improved capability and to produce the selected IMPALA demonstrators. These systems demonstrated all the developments that had taken place across the project including the DI, the toolpath generator, simulation interface results and monitoring system. The impact on the production of the demonstrators compared with conventional manufacture was assessed.

The IMPALA systems were demonstrated at the month 42 and month 48 meetings, with the additional production of the IMPALA video to explain the concept and achievements of the IMPALA project. The video can be found on the IMPALA website and the EC dissemination webpage (please see http://www.impala-project.eu.com online) and each partner has a copy for dissemination activities.

Achievements of project objectives

The IMPALA project focused on three key objectives for the development of LAM processes for industrial applications. The objectives outlined at the start of the project were, customisation, miniaturisation and cycle time. The project achieved these objectives with the following technological achievements.

1. Customisation - IMPALA aimed to demonstrate that the developed technologies will be used for the low-volume, high cost manufacture of both macro-size and micro-sized components with the flexibility and complexity that are demanded by the industries within the project.

This objective was achieved through the Wisildent dental bridge application, this allowed patient CT data to be used to produce individual customised parts. Multiple (up to 10) individual implants can be produce in one build using powder bed lamp processing.

2. Miniaturisation - IMPALA laser technology, delivery, and powder manufacture will be developed to build features as small as 20 µm.

Work to achieve the objective miniaturisation was carried out for both the blown powder technology and powder bed techniques. It was noted through the project that 20 µm feature size would be very difficult to achieve. For the blown powder technology miniature nozzles were designed and manufactured by IWS and several examples were built.

A miniature pyramid was also produced using the nozzle.

Finally, a complex miniature geometry was achieved, a double helix with a height of 5.5 mm and a single track 100 µm with a torsion of 140 degrees.

For the powder bed technology the WP 6 'fallback demonstrator' showed that consistent miniature feature size for the equipment was 0.1 mm.

3. Cycle-time - To achieve a similar productivity (and thus cost-efficiency) for one-off or small-to-medium volume products when compared to conventional manufacturing, significant development is required in terms of the rate of powder deposition, process information management and tool path generation.

There are three clear examples of where the objective of cycle time has been achieved in the IMPALA project. The first example is for the OSVAT valve seat cladding. When compared to the conventional plasma arc deposition it was found that the laser deposition process was much improved and offered a cycle time of approximately 25 seconds and a near net shape deposit, minimising post processing efforts.

The second example is the Wisildent dental bridge where currently the components are handmade and finished taking up to two days and very labour intensive. However, using laser powder bed technology the cycle time can be reduced to 30 minutes per part. A final finishing process is still required to achieve the surface finish requirements.

The final example is the IMPALA demonstrator component the metal leading edge, the component when produced using laser processing and final milling can significantly reduce cycle time, material waste and cost.

Potential impact:

The IMPALA project has demonstrated that LAMP also recently known as additive manufacturing technologies can offer distinct advantages and solutions for the manufacturing of products that often require customisation and miniaturisation along with reduction of cycle time as a standard requirement. The application markets include automotive, aerospace and medical. The results of this project will contribute to the emerging industrial applications of AM in Europe. The IMPALA end users have confirmed their interest and have already started the designs of new products utilising the IMPALA results.

The LAMP are used almost exclusively on complex geometries, durable and high-valued components e.g. for aero engines and medical applications. This involves meeting high safety standards and fulfilling very high quality and documentation requirements. Manufacturing companies have a possibility to integrate and propose new solutions to their customers which in turn will help to create new jobs.

At the final review meeting, the consortium made an assessment of the technical highlights from the project. This was to assess the overall achievements of the project, these will attribute to the impact of the project to both the consortium members and the wider public:
- miniaturisation aspects of dental bridge;
- reduced cycle time for the dental bridge;
- greater potential for further miniaturisation;
- potential to work on large components;
- customisation combined with miniaturisation work;
- CAD to part achievements;
- demonstration of process stabilisation on large parts;
- reduced cycle time for MLE production;
- versatility of the process in general;
- monitoring and control system for blown powder;
- CAD to part and quality control;
- digital interface;
- smooth data flow;
- operator support;
- advancements and availability of fine powders.

The project results have helped to widen the range of materials that can be used in additive manufacturing by developing novel aluminium alloys and ceramic powders bringing the potential to market new alloys and their processing or develop new processes for companies.

These innovations will both facilitate new customisation and increase the freedom of design by broadening the choice of materials.

The developed technologies have enabled the manufacturer to interrupt defective processes in time to initiate corrective processing strategies, and fulfilling the relevant quality assurance documentation requirements (DIN ISO 9000 ff., VDA 6.1) e. g. for safety-relevant components. Furthermore, the technologies speed up the process development for the variety of geometries and materials and provide a significant reduction of time to market. This improves EU competitiveness by providing a step change in the quality of manufacturing for components for many industrial sectors from aerospace to health care, and by minimising time between concept and product.

The use of robots has a wide socio-economic impact in Europe. When competing with non-EU countries that offer cheaper labour costs, the use of robots can prevent the dislocation of whole plants by lowering the production costs and hence increasing productivity. Also, the replacement of simple human resources by specialised persons, capable of programming robots, will benefit overall productivity.

The following is a resume of the partner benefits as stated by them on that they have felt the IMPALA project has achieved.

Beneficiary 1 TWI

- TWI has benefitted from the development of new processing parameters for Laser AM techniques and new materials, including aluminium, ceramic and finer titanium powder. Development of TWI technology capability for industrial applications including the MLE, dental implants, cochlear implants and valve seat cladding for the proof of concept and potential adoption of IMPALA technology.
- Other benefits include technology developments for finer powder feeding for both powder bed and blown powder technology, in addition to the use of DOE for valve seat cladding. These developments within the project will allow TWI to continue with LAMP developments and assist member companies in adopting the technology.

Beneficiary 2 BCT:
- working on new technologies with big market potential;
- international collaboration between SMEs, researches and industry;
- gaining deeper knowledge of AM processes.

Beneficiary 3 GOM:
- use of fast acquisition scanning of AM components and comparison to CAD data;
- development of contacts using AM.

Beneficiary 4 NedClad:
- withdrew from the project at month 18.

Beneficiary 5 TLS:
- first company on the market who offers spherical Ti powder with a d50 of 10 µm;
- fine titanium powder already sold.

Beneficiary 6 NORCAM:
In order to increase the amount of robots in EU's industry, the tool path generation must be simplified and teach and learn programming should be replaced, since it does not allow off line programming and optimization is difficult. The algorithms developed during the Impala project are versatile and can be used not only for laser deposition, but for machining or cutting, as well. Norcam gained a lot of experience in controlling and handling robots and was able to implement several robotic cells, meanwhile.

- Development of algorithm to post process regular tool paths obtained with existing CAM packages for six axis robots.
- Software pack availability expected until the end of 2013.
- Sales 2013 expected six units.
- Product recommended price tag circa 20 k.
- Experience in handling and supporting off line CAM based robot programming.

Beneficiary 7 MIC:
- alternative usage of additive manufacturing is now a reality for Micronormas' products. It's use is still rather short due to the need of high end parts which are not always the day to day production, since we manufacture all kind of tool parts for machines.
- widening of the R&D and B2B network;
- consolidation of product development procedures and creative tools;
- increasing capabilities in the fields of additive manufacturing, micro-manufacturing and electronics.

Beneficiary 8 WIS:
- increased our know-how on laser sintering system and CAD-CAM system;
- new products to be taken to the dental market offering new products.

With the knowledge and experience developed in IMPALA, AM technologies can be used in various fields of applications. New part manufacturing will be supported as well as repair tasks or the production of individual implants. Wisildent has great interest in taking new products based on new technologies to the market. The IMPALA project gave Wisildent the opportunity to increase both the type and the number of prosthesis already being produced by the company.

Now, it will be possible to differentiate the offer through different clients also for all the metal prosthesis we already did in the past ('old and new' method). This will give Wisildent the possibility to create a corporate advertising that, hopefully, will bring to us high visibility on our clients or possible clients. Directly connected to this Wisildent will increase the number of employments dedicated to this application.

Beneficiary 9 OSVAT:
- knowledge on alternative technology to weld stellite on the seat of the valve;
- saving powder during the deposition;
- results have shown saving welding and machining time.

Beneficiary 10 WOL:
- possibility to coating steel holder with hard metal like Tungsten carbide obtaining strong connections and similar hardness as hardened tool steel.

Beneficiary 11 Polyshape:
Polyshape is now prospecting in new markets. During the project, new materials have been developed and tested. The medical market is a high potential market for customised implant. Our company is now producing parts since 2010. This market is growing of 20 % per year. One new employee is in the company for this project and will stay after the end of the project. Some partners are now customers or suppliers for the company.

- Development of the powder bed technology, optimising the quality and the productivity.
- Use new materials and new powders.
- Increase our expertise on the medical (customised parts) and aerospace (complex geometries) market.
- Produced very complex parts, with innovative designs and functionalities.
- One new employee hired during the project to remain with the company.

Beneficiary 12 Cochlear:
The project results revealed that LAM is not a suitable manufacturing process for building high-precision mechanical assembly parts for active implantable devices. Although the technology has high potential in terms of production lead times, cost and customization, it is difficult to meet all tolerances.

- Cochlear gained knowledge about state-of-the-art laser additive manufacturing techniques and related equipment and tools. The established network will allow Cochlear to get easier access to the most appropriate partners for process engineering and material supply.

Beneficiary 13 GE:

IMPALA project provides a change in the speed of manufacturing processes for many industrial sectors from aerospace by decreasing time between concept and product typically from weeks to hours. By conventional methods, it takes approximately two weeks to finish the metal leading edge part however, by this new manufacturing process it takes only nine hours and this is achieved by eliminating the moulding and machining phase of the conventional process. From the economical point of view, the effect of this new technology on the manufacturing process for turbine blades may result in an annual cost saving of approximately EUR 300 000 (GE).

- Involvement in the IMPALA project enhanced a good team to develop this new technology. It was also a great benefit to experience the similar technological studies, developments in the European partners.
- The good collaboration between the partners resulted in a high productive, efficient four-year period and also forward planning.
- Costs savings applied to MLE type products, techno-economic study.
- USD 27 million costs savings per year in raw material and processing; only 1/6 of the original raw material is needed using Impala process.
- 10 year market outlook proposes gains in costs savings up to USD 42 million per year due to enhancement and increased efficiency of the LAM processes, if they were to take into production.

Beneficiary 15 CERAM:
- the project will benefit the company in taking forward and offering further assistance in the development of materials and materials characterisation.
- It has also helped CERAM understand the market for services in additive manufacture better.

Beneficiary 18 IST:
- Further development of LAM technologies for ILT.
- Development of microcladding system to be exploited further by the university.
- Development of European network of SMEs, companies and research organisations.

Beneficiary 19a ILT:
With the gained experience and knowledge of the Impala process, particularly in build-up of miniaturised structures and complex geometries, Fraunhofer will support other manufacturers using the blown powder process to build-up customised parts in high quality with low costs, in short processing time with a minimum of material input.

- The developed technologies will strengthen the activities of ILT in the field of LAMP. The technical expertise can be adapted to other areas in laser material processing.
- Another benefit is the European network of SMEs, companies and research organisations.

Beneficiary 19b IWS:
- Due to the IMPALA project an improved powder nozzle was designed and manufactured by Fraunhofer IWS. Based on these results the high precision micro cladding will be further improved and qualified for industrial applications.
- Many experiences were gained at generating and building-up of precise and complex parts, which help to be successful in further research projects for industrial applications.

List of websites:

Since the start of the project, IMPALA has had a dedicated website, http://www.impala-project.eu.com. This has been and will be in the future crucial to the dissemination objectives of the project. Internet is today the sole most efficient media of communication and thus it is our single most important dedicated disseminating tool.

The site features two main goals: it functions as a source of information for the broader community of users and also as a vault of specific project information available only for the project partners.

It is used not only to explain and promote the technology, either using general information or more detailed case studies information, but also to link the project to the partner's community and other interesting sites and projects.

Towards the end of the project a video showing the accomplishments of the project was produced and can also be viewed on the project website.

The project website is maintained by TWI the project coordinator and can be accessed through the details on the front of this report.

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