Final Summary ReportEuropea Microfusioni Aerospaziali, S.p.A.BeneficiaryEUROPEA MICROFUSIONI AEROSPAZIALI, S.p.A.

R&D project start date: January 1, 2015

R&D project end date: June 30, 2018

Project Partners

REIM

FLAME SPRAY

MOSAICO

OFFICINE DI MATTEO

ECOR

Program Technical Manager: First Name, Last Name, Position, Educational Qualification

Dr. Michele Di Foggia, R&D Manager at EMA, Ph.D. in Physics, Master’s degree in Materials Science

Number of employees working on the development and research projects

The total number of employees—comprising researchers, technicians, and support staff—was 85, of whom 35 worked for the RI and 50 for the SS.

1. Project Objectives

The objectives set forth in the approved development plan are listed below, along with the titles of the ORs and the related activities.

OR1. Research and development of innovative manufacturing strategies for the processing, inspection, and assembly of wax component clusters for investment casting (RI+SS)

For this reason, the project includes:

Activity 1.1. Development of innovative methods for assembling wax clusters with minimal manual labor through the design and production of new multi-cavity molds and the reduction of molding cycles.

Activity 1.2. Research, development, and refinement of innovative automation processes for the inspection and assembly of wax palettes.

OR2. Research, development, and refinement of innovative technologies for melting furnaces

Activity 2.1. Design and development of an innovative DSX large-chill cluster structure to improve metallurgical performance in terms of grain structure (grain boundaries), specifically designed for the use of complex radiative baffles, with a smaller cross-sectional area and therefore capable of increasing thermal gradients during the extraction phase.

Activity 2.2. Study and development of a more efficient temperature monitoring system for MANSIGN melting furnaces, in both the small-bore and supersmall-bore configurations, capable of ensuring more efficient and robust temperature control

OR3: Research, development, and optimization of new precast, cast, and post-cast technological solutions to achieve improved surface and subsurface conditions for superalloy turbine blades

Activity 3.1. (RI and SS Activities) Study of the interaction mechanisms between the superalloy and the ceramic shell to develop new and optimized process formulations for the manufacture of the shells and for the casting of the superalloy

Activity 3.2 (RI+SS activities) Study on the influence of casting processes on major surface and subsurface defects.

Activity 3.4 (SS activities) Development of best manufacturing practices to reduce rework and costs.

Activity 3.5 (SS activities) Development of the most suitable technological/engineering solutions to ensure consistent quality and standardization of post-cast removal processes.

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

• Officine Di Matteo (OR3, Section 3.3), concerning the study and development of the knock-out process for ceramic shells;
• ECOR (OR4), concerning the welding of plates used to seal holes in multi-chamber stators using an automated laser system;
• Flame Spray (OR5), regarding coatings on turbine blades (particularly the aluminized portion);
• Mosaico (OR1), concerning the introduction of augmented reality techniques to benefit production and maintenance workers in factories

2. Final Results of the Project

The project’s overall objectives were met.

Overall, the project contributed to the development of technological solutions capable of delivering benefits in the following ways:

• reduction in cycle times for the wax area through the introduction of multi-cavity molds, automation of the wall thickness measurement process, and modifications to post-cast operating cycles, resulting in lower final costs;
• improved performance, such as through the redesign of the clusters and their baffles, as well as all improvement measures achieved through minor modifications to the casting process for equiaxial and directionally structured products, thereby reducing defect rates and resulting in lower final costs;
• optimizing workstations to make them more ergonomic

With regard to the wax area, multi-cavity molds were designed and manufactured for the support parts of the assemblies, resulting in significant cost savings; however, for the blades, it was not cost-effective to proceed in this direction following the verifications conducted after the studies were completed. The issue of automation was addressed by inserting platinum pins through the development of a dedicated automated work cell, which was successfully qualified during the first SAL. In the automation sector, the development of the automatic wall thickness measurement system was successfully completed using a work cell that employs ultrasonic probes. In the mold area, activities primarily involved experiments to modify mold recipes in order to reduce surface defects and understand the interactions between the ceramic mold material and the superalloy during casting—interactions that are often the source of many problems in the cast metal. With regard to the casting area, casting and filling profiles—including innovative ones such as “bottom pouring” and “melting profiles”—were studied, along with technological solutions such as variations in dwell times, casting recipes, etc., to investigate their contribution to resolving various defect issues, using different case studies for this purpose, as specified in the project’s technical specifications. As a result of these activities, both isotropic components and components with a directional and/or single-crystal structure have benefited from increased yield due to a reduction in initial defects. In this context, the ability to design new cluster configurations for DS and SX blade assemblies, combined with the use of numerical modeling, has demonstrated that the proposed solution improves dendrite structure and has the potential to reduce scrap rates during grain inspection. Therefore, this technique will be further investigated with a view to its potential industrialization. The findings from the studies conducted to control the casting process were also significant, leading to the patenting of the method studied (Italian Patent No. 102016000057262), which is available at https://patents.google.com/patent/WO2017208275A1/en.

In the finishing area, improvement measures were developed and more functional workbenches were implemented; efforts were also made to enhance ergonomics and work quality, with the goal of optimizing workstations through gradual improvements. The targeted design for work areas in need of improvement also focused on noise reduction, achieving significant results through passive methods (sound-absorbing panels), the redesign of machinery geometries, and the introduction of headphones for active noise control.

3. Features and Performance of the Developed System

OR1

Production of a multi-cavity mold for the Large Chill assembly configuration: benefit achieved = reduction in:

• 48 minutes for a single bunch;
• 90 minutes for 10 bunches

compared to the same configuration obtained using traditional molds.

Development of a multi-cavity mold for the Small Bore assembly configuration: benefit achieved = reduction in the time required for:

• 21 minutes for a single bunch;
• 29 minutes for 10 bunches
• 104 minutes for minor work at the workbenches

compared to the same configuration obtained using traditional molds. The photo below shows one of the molds produced.

Fig. 1 One of the molds created as part of the project

Development of an automated cell for inserting Pt pins, which resulted in the benefits listed in the table below:

 

Fig. 2 Benefits achieved through the automation of Pt-pin insertion and a detailed view of the machine developed as part of the project

Development of an automated cell for measuring sheet wall thickness using ultrasonic technology. The development of the robotic cell for thickness measurement using ultrasound has eliminated variables associated with operator error. The measurement times achieved with the robotic cell are in line with expectations. A photo of the automated measurement system developed is provided below.

 

Fig. 3: On the left, an automated system for measuring the wall thickness of turbine blades, developed as part of the project. On the right, the conventional measurement method and the measurement sensor developed for the robot.

OR2

The results achieved with this Implementation Objective were as follows:

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 allowed for smaller interdendritic spacing compared to the standard case and, therefore, a lower probability of secondary grain formation, since the dendrites are compacted more effectively. Therefore, this represents an improvement aimed at increasing the yield of single-crystal products through a substantial modification of the casting cluster design and its associated baffles. Below are some photos illustrating the results achieved.

 

Fig. 4 Newly developed baffle (left) designed to allow the newly designed cluster (right) to flow, developed as part of the project

A new method for verifying the correct setup and calibration of the optical pyrometer, which can be used during the production cycle. The new method involves automatically inserting the temperature probe directly into the furnace’s hot chamber, at the specific location relevant to the casting process, rather than through the pouring channel—thus under actual process conditions (during the operating cycle). As a result, temperature control becomes more reliable and efficient, with an overall reduction in machine downtime. The ability to monitor at a higher frequency allows, even in the event of temperature issues, the problem to be isolated to a very small number of ingots compared to the initial situation. In addition, a “predictive” system has been implemented that alerts the operator to an incorrect temperature reading, enabling immediate intervention by calibration technicians.

OR3

The main results achieved through the R&D activities of this Implementation Objective were as follows:

Based on numerous experimental test campaigns conducted on the shells and the manufacturing process, it was determined that the interface is indeed critical for the occurrence of surface and subsurface defects. In particular, the study focused on the issues of “plus metal” and “dross” defects.

1. “Excess metal” issue: Testing with a new cubic filler in the manufacturing formulation for ceramic shells led to improvements in the surface conditions of the stator blades. However, it was not possible to modify the composition for all part numbers of potential interest, as this would have required a significant amount of time and incurred additional requalification costs.

2. The issue of dross (hafnium oxide), which affects various components—both directional and equiaxed—was addressed through an extensive experimental campaign involving tests on the various process steps, resulting in a solution that blocks the dross, confining it outside the blade. The solution consisted of introducing a ceramic filter positioned between the blade and the chill plate, as shown in the photo.

Fig. 5 The dross problem was drastically reduced by using the inserted filter, the solution for which was developed as part of the project

This led to the development of measures to mitigate the problem, while the cause of the problem itself can be attributed to the interaction of the hafnium in the superalloy with oxygen present in the ceramic material (e.g., the primary layer of the shell) or elsewhere (such as the oxide on the chill plate). Tests were conducted to coat the chill plate with silicon nitride (the green-fuchsia portion of the photo below), but they will need to be repeated since the results obtained were not conclusive.

Fig. 6 Silicon nitride coating on the chill plate for dross reduction tests; the solution for these tests was developed as part of the project

3. Optimization of processes for two types of alloys to improve casting yield for products with DS and EQX structures, based on the experimental campaigns conducted.

Development of new strategies and methodological solutions for planning machining and rework operations for post-cast corrections and NDT inspections, which are designed to optimize the sequence of operational cycles, thereby allowing:

– NDT inspections to be performed earlier than in standard work cycles, thereby allowing for product rejection before its value increases further—with clear economic benefits;

– shorter cycle times by reducing the impact of specific treatment phases required for NDT preparation during correction cycles, by performing only local corrections based on a maximum number of defects.

Design and construction of an ergonomic workbench through the introduction of a specialized manipulator to optimize the workstation, as shown in the figures below.

Fig. 7 Innovative solution for finishing operations: an ergonomic manipulator developed as part of the project

The noise mitigation solutions proposed following simulations conducted using appropriate software and sound level measurements in the work areas would, overall, result in a reduction in the SPL value of approximately 20 dB in common areas and approximately 15 dB at the operator’s workstation.

Fig. 8 Noise Level Measurements in Production Areas

Further improvements in noise mitigation are achieved through the use of ANC headphones for active noise cancellation, which is particularly effective at mid-to-low frequencies, where the proposed passive mitigation solutions are less effective.

Fig. 9 Different levels of noise reduction achieved with the solutions identified in the production departments

The proposed solutions to address the problem are:

• Use of Sound-Absorbing Panels in the Ward
• Redesign of a workbench using sound-absorbing elements
• Equipment Redesign
• Introduction to ANC headphones (and try them out by purchasing a pair of ANC headphones) for active noise cancellation, as shown in the image below.

4. Eligible and Reported Expenses5. Publications

A “Handbook of Metrology in Industrial Production” is currently being published; Chapter 1.5 discusses industrial automation solutions, including the one developed in collaboration with the WZL laboratories at Aachen University (http://www.wzl.rwth-aachen.de).

6. Effects of the program

The project, carried out in collaboration with partners from the POEMA Network, has yielded tangible improvements resulting from the study and the research and experimental activities undertaken. The study was systematic and encompassed the entire manufacturing process, thoroughly investigating the various issues typical of lost-wax casting—from ceramic components to wax components, and from assembly techniques to removal, finishing, and inspection procedures. In summary, therefore, the project’s results were in line with the technical specifications, generating expertise that places EMA at the cutting edge of technology in its sector. The results discussed in the previous sections have all been transferred to production, while others (the noise mitigation measure) have not yet been implemented due to budget constraints. Still others (such as “bottom pouring”) are more difficult to implement due to technical challenges and a lack of effective support from qualified suppliers. The impact of the research project is significant in that it consolidates industrial development know-how that is unique in Italy—namely, lost-wax microcasting—where the combination of the partners’ industrial and technological expertise leads to greater profitability, defined as an increase in added value, lower costs, and reduced time in the development and production of the “turbine blade.” The R&D project enabled the partners in the POEMA network to optimize their products and manufacturing processes thanks to the innovations introduced, allowing them to implement improvements capable of generating economic benefits (primarily attributable to lower costs resulting from reduced scrap) and employment opportunities. It also benefited from the geographical proximity of the partners in managing and resolving scientific and technological issues, as well as purely industrial problems related to manufacturing cycles. Thanks to the project, a virtuous cycle of research commercialization has been set in motion, capable of generating an exponential multiplication of results once fully operational.