CDS_PAC_14 - PoEMA R&D project

Final Resume

Europea Microfusioni Aerospaziali SpA

Beneficiary and total period

EUROPEA MICROFUSIONI AEROSPAZIALI SPA

Start date 01/01/2015

End date 30/06/2018

Project Partner

REIM

FLAME SPRAY

MOSAICO

OFFICINE DI MATTEO

ECOR

Technical manager of the program: Name, Surname, Qualification

Dr. Michele Di Foggia, EMA R&D Manager, graduated in Physics, Master in Material Science

Number of employees in the R&D project

The total number of employees, divided between researchers, technicians and auxiliaries was 85 units, of which 35 for the Industrial Research and 50 for the Development.

1. Items of the project

The items of the project are listed below.

WP1. Study and development of innovative manufacturing strategies for processing, checking and setting up of the wax assemblies

For this reason, the project includes:

Task 1.1. Development of innovative methodologies for setting up of the wax assemblies and with a reduced number of manual processes through the design and manufacture of new multi-cavities dies, and reduction of molding cycles.

Task 1.2. Study, development and fine-tuning of innovative automation processes for the control and assembly of the wax blades.

WP2. Study, development and fine-tuning of innovative technologies for melting furnaces

Task 2.1. Study and development of an innovative DSX large chill assembly structure for the improvement of the metallurgical performance in terms of grain boundaries, specifically designed for the use of complex radiative screens (baffles), with a smaller areal aperture and therefore able to increase the thermal gradients during the withdrawal phase.

Task 2.2. Study and development of a more efficient temperature monitoring system inside the MANSIGN melting furnaces, in the two configurations (small bore and super-small bore), capable of ensuring more efficient and robust temperature control

WP3: Study, development and fine-tuning of new pre-cast, cast and post-cast technological solutions to obtain better surface and sub-surface conditions of the superalloy turbine blades

Task 3.1. Study of the interaction mechanisms between superalloy and ceramic shell to develop new and optimized process recipes for shell manufacturing and superalloy pouring.

Task 3.2 Study on the influence of casting processes on the main surface and sub-surface defects.

Task 3.4 Development of the best manufacturing techniques to reduce rework and costs.

Task 3.5 Development of the most suitable technological / engineering solutions for a fixed quality and standardization of post-cast removal processes.

In addition to the identified WPs, EMA participated in the R&D activities of:

  • Officine Di Matteo (WP3, task 3.3), concerning the study and development of the knockout of ceramic shells;
  • ECOR (WP4), concerning the welding of the plates to close the holes in the multi-vanes components, by means of an automatic laser system;
  • Flame Spray (WP5), concerning the coatings on the turbine blades (especially on the aluminization part);
  • Mosaico (WP1), concerning the introduction of augmented reality techniques for the benefit of production / maintenance operators in the factory

2. Final results of the project

The general objectives of the project have been respected.

Taken as a whole, the project contributed to the development of technological solutions capable of bringing benefits in the following way:

  • reduction of cycle times for the wax area with the introduction of multi-cavity dies, with automation in the measuring process of the "wall thickness", modification of post-cast operating cycles, with a consequent reduction in final costs;
  • improvement in yield, as in the case of the new design of the assemblies and of the related baffle and all the improvement actions obtained with small changes in the casting process for EQX and DSX products, reducing their defects, with a consequent reduction in the final costs;
  • optimization of workstations to make them more ergonomic

In the wax area, a multi-cavity dies have been designed and manufactured for the support parts of the assemblies (feeders, continuators, etc..), allowing significant savings. The topic of automation was addressed with the insertion of platinum pins through the development of a special automatic work cell, successfully qualified in the first SAL. In the automation field, the development process of the automatic wall thickness acquisition system was successfully completed, using a work cell that uses ultrasound as a probe. In the shells area, the activities mainly concerned experiments to modify the shell recipes in order to reduce surface defects and understand the interactions between the ceramic shell material and the superalloy during casting, often the source of many problems on the metal melt. In the casting area, casting and filling profiles have been studied, like the "bottom pouring" and the "melting profile". Also, other technological solutions have been proposed, such as the variations in the soak times, the casting recipe, etc…, to investigate their contribution to the defect reduction, using for this purpose, different case studies, as required by the project. From these activities, both equiaxed components and components with a directional and / or monocrystalline structure have obtained benefits, increasing the yield thanks to the reduction of the defect numbers. The results of the studies adopted for the control of the melting process were also important, so that the method studied was also patented (Italian patent No. 102016000057262) and available onhttps://patents.google.com/patent/WO2017208275A1/en.

In the finishing area, improvement solutions were studied and more functional work benches were adopted and we worked on the ergonomic aspect (of the benches), to optimize the workstations with gradual interventions. We studied the noise in some critical shop floor area, and designed a proper solution in order to mitigate it by using “passive methods” (sound-absorbing panels), design of different geometries of the machinery and through the introduction of headphones for the active noise control (ANC).

3. Characteristics and performances developed with the project

WP1

Multi-cavity dies realization for the Large Chill assembly configuration: benefit = reduction of production times by:

  • 48’ per each assembly (cluster of blades);
  • 90’ per 10 clusters

compared to the same configuration obtained using traditional molds.

Realization of multi-cavity die for the Small Bore assembly configuration: benefit = reduction of production times by:

  • 21’ per each assembly (cluster of blades);
  • 29’ per 10 assemblies
  • 104’ during the work on the benches

compared to the same configuration obtained using traditional dies. In the photo below, one of the dies designed and manufactured.

Fig. 1 Uno degli stampi realizzati con il progetto

Creation of an automatic cell for the insertion of Pt-pins, which led to the advantages expressed in the table below:

 

Fig. 2 Advantages achieved with the automation of the insertion of Pt-pins and detail of the machine developed with the project

Realization of an automatic cell for measuring the thickness of the airfoils using ultrasound technique. With this robotic cell it is possible to eliminate the variables related to the operator. The measurement times obtained with the robotic cell are in line with what was expected. The photo of the developed automatic measuring system is given below.

 

Fig. 3 On the left, Automated system for measuring the thickness of the aifoils of the turbine blades, developed with the project. On the right, the classic measurement methodology and the measurement sensor developed for the robot

WP2

The results achieved with this work package have been the following:

For the filling system (EQX case), there are no substantial differences between the BOTTOM POURING system and the standard TILTING system.

The use of new "closed" baffles together with a different feeding system has made it possible to have smaller interdendritic spacings than in the standard case and therefore less probability of the occurrence of secondary grains, since the dendrites are compacted more effectively. Therefore, this is an improving condition, which goes in the direction of increasing the yield of products with a monocrystalline structure by means of a substantial modification of the design of the casting assembly and of the related baffle. Here are some explanatory photos of what has been achieved.

 

Fig. 4 On the left, New baffle developed to pour the new assembly (on the right), developed in the project

New method of checking the correct setting and calibration of the optical pyrometer, which can be used during the production cycle. The new method provides for the automatic insertion of the temperature probe directly inside the hot chamber of the furnace, in the position of interest for the casting process, and no longer from the pouring channel, therefore in process conditions (during operation) . Thus, temperature control becomes more robust and efficient, with an overall reduction in downtime. The possibility of working with a higher monitoring frequency allows, even in the case of temperature problems, to isolate the problem on a very small number of assemblies, compared to the initial situation. In addition, a "predictive" system has been created, which warns the operator of an incorrect temperature value, and permits an immediate intervention of the calibration technicians.

WP3

The main results obtained from this work package have been the following:

From the numerous experimental test campaigns conducted on the shells and the manufacturing process, it was estimated that the interface is actually critical for the onset of surface and subsurface defects. In particular, the study focused on the issues of plus metal and dross defects.

1. “Plus metal” problem: The experimentation with new cubic stucco in the manufacturing recipe of the ceramic shells has allowed obtaining improvements in the surface conditions of the multi-vanes. However, it was not possible to change the composition for all part numbers of potential interest as this would have required a lot of time and additional requalification costs.

2. The problem of dross (Hafnium oxide) affecting various components, both with a directional and equiaxed structure, was studied with a massive experimental campaign with which tests were conducted on the various process steps and a solution was found (which stops the dross, confining it out of the blade). The solution consisted in the introduction of a filter, in contact with the chill plate, as in the photo.

Fig. 5 Dross problem drastically reduced using a filter in contact with the chill plate

The cause of the presence of haphnia is attributable to the interaction of the hafnium in the superalloy with the oxygen in the ceramic material (i.e. primary shell layer) or elsewhere (oxide in the chill plate, for example). Tests using a coating of the chill plate with Si3N4 (see the photo below) have been made to realize a not-oxide shield, but we have had not clear results.

Fig. 6 Coating of the chill plate with silicon nitride for dross reduction tests

3 Development of the process for two types of alloy to improve the performance of the products with DS and EQX structure, through the experimental campaigns carried out.

Development of new strategies / methodological solutions to optimize the succession of operating cycles allowing:

- the anticipation of NDT checks with respect to standard work cycles;

- shorter cycle times, by making only local corrections.

Design and construction of an ergonomic workbench by introducing a special manipulator to optimize the workstation, as shown in the figures below.

Fig. 7 Innovative solution for finishing processes: ergonomic manipulator developed in the project

The noise mitigation solutions proposed following simulations conducted with appropriate software and sound level measurements in the shop floor (finishing area), would overall lead to a reduction in the SPL value of about 20 dB in the common areas and about 15 dB in correspondence with the operator.

Fig. 8 Noise level measurements in the finishing area

Further increases in the mitigation action are obtained with the adoption of ANC headphones for active noise reduction, particularly effective for medium-low frequencies, where the passive mitigation solutions proposed are less effective.

Fig. 9 Different levels of noise reduction with the solutions identified in the finishing area

The solutions proposed to overcome the problem are:

  • Use of sound absorbing panels in the finishing area
  • Work bench redesign, using sound absorbing elements
  • Equipment redesign
  • Introduction of ANC headphones (and experimented with the purchase of a pair of ANC headphones) for active noise reduction

4. Admitted and final expenditures

5. Publications

A "Handbook Metrology in Industrial Production" is being published, where in chapter 1.5 the industrial automation solutions are discussed, including the one developed in collaboration with the WZL laboratories of the Aachen University(http://www.wzl.rwth-aachen.de).

6. Final considerations

The project concluded in collaboration with the partners of the POEMA Network has produced tangible improvements resulting from the study and research and experimental activities carried out. The study was systemic and embraced the entire manufacturing process, thoroughly investigating the various issues, typical of investment casting, from ceramic to wax components, from assembly items to finishing and inspection techniques. In summary, therefore, the results of the project were in line with those of the technical specifications, generating a knowledge that places EMA at the state of the art in the technologies of its sector. The results discussed in the previous sections have been transferred in the production, while others (i.e. the noise mitigation intervention) have not been implemented yet. The impact of the research project is important because the know-how in the investment casting has been consolidated. The merging of the industrial and technological skills of the partners leads to greater profitability, increase of the added value, lower costs and time in the development and production of the “turbine blade” product. The R&D project has allowed the partners of the network POEMA to develop their own products and manufacturing processes in the best possible way, thanks to the innovations introduced.