National Center for Manufacturing Sciences News and Views from the World of Manufacturing
August 2012 Welcome to The CTMA Connector, a monthly newsletter designed to provide news and ideas about the Commercial Technologies for Maintenance Activities (CTMA) program. The CTMA program is a joint Department of Defense/National Center for Manufacturing Sciences (DoD/NCMS) effort promoting collaborative technology development between industry and the DoD maintenance and repair facilities. This newsletter highlights ongoing projects, serves as a forum for promoting new project ideas, and provides other news of interest to the program. Our goal is to stimulate your participation and solicit your input.
Feel free to submit items for the newsletter as well as any suggestions to make it more useful. More information about the program can be found at http://ctma.ncms.org/.
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SAVE THE DATE:2013 CTMA Symposium – Fast Track Collaboration
8-10 April, 2013 in the Washington, DC area. Plan to participate.
Come Visit NCMS/CTMA at the 2012 Defense Maintenance Symposium, 13-16 November in beautiful Grand Rapids, Michigan. Vote us best booth again where we will be showcasing five of our member companies and their capabilities including:
Curtiss Wright Corporation
New CTMA Project: Joint Test Protocol for Gas Turbine Engine Materials
A bench level joint test protocol to accurately recreate hot section wear, plugging, glazing, and Calcium-Magnesium-Alumino-Silicate (CMAS) formation on turbine engine components does not exist.
This project will design a CMAS-forming sand and dust fine media which will ultimately be used to aggressively screen low performing components/protective systems and replicate degradation similar to the most problematic dusts on ingestion into an operating gas turbine engine in the SWA theater of operations. Assorted synthetic and natural sands and dusts used in typical erosion tests do not produce the effects observed in engines and components returned from the field.
Requirements of the test sand includes:
The particle sizes of the dust will need to be small enough to bypass the particle separators, and collect in eddy spots.
The dust composition will also need to react chemically and thermally on heating to produce CMAS deposition that chemically attacks standard thermal barrier coatings, thereby exposing base metal to high temperatures and negatively affecting blade aerodynamics.
The material must be Continental United States (CONUS) sourced in amounts that are useful for DoD bench level and original equipment manufacturer (OEM) full-scale engine test purposes.
CTMA Project Completion: Inspection and Repair Preparation Cell (IRPC)
IRPC represents a direct response to reducing sustainment cost by increasing the availability and reliability of critical composite structures through replacement of artisan dependent inspection and repair operations with computer-based technology. The current manual practice includes tap testing as the detection method, manual scarfing to remove the defect, and manual patch preparation. These activities all contribute elements of inaccuracy and waste.
Five NCMS industry partners teamed with eight Department of Defense (DoD) and federal organizations to identify and demonstrate a suite of integrated technologies to achieve the goal of streamlining the repair process as well as introduce elements of consistency and high quality.
The baseline artifact selected for evaluation of the technologies was the C-130 Radome although the technique can be applied to new aircraft program materials to identify manufacturing defects as well as structures being refurbished. Defects include delamination, physical damage, and presence of moisture. Computer numerically controlled (CNC) motion techniques coupled with optical scanning are used to establish a geometric data base tied to a reference coordinate system for the specific structure being evaluated. Shearography, being a global non-destructive inspection (NDI) technology, is then used to identify suspect areas within the structure for further evaluation. Using the reference coordinate system as a guide, the suspect areas are further inspected using more probing terahertz NDI technology to establish defect types, boundaries, and depth of the defects. The two step evaluation technique results in high definition defect data in an acceptable elapsed time. The data is overlaid onto the Radome surface using a laser projection system for visual identification of defect areas.
The IRPC when fully integrated will use CNC technology to automatically scarf defect areas, cut appropriately shaped repair patch materials, and guide the repair technician in the repair process. Benefits are in the form of consistency of repair, cost reduction, lead time reduction, and retention of structure historical data. While the fully integrated IRPC will maximize the benefits obtained, the individual technologies will provide immediate benefits. Downscaled versions of the IRPC can be implemented in a building block fashion and is presented as an alternative transition path.
The primary objective of the IRPC Phase I project was to evaluate and demonstrate the enabling technologies required to achieve the vision of an automated inspection and repair cell for composite structures (Figure 1). The C-130 Radome was selected to serve as the basis for the evaluation.
The project concluded with a successful demonstration of applicable technologies resulting in the machine tool based removal of composite material at controlled depths to the single ply level of accuracy. This demonstration led to the development of a concept for the fully implemented IRPC (Figure 2).
NDI techniques were evaluated for the identification of defects in Radome type structures. Evaluation has shown that the most appropriate implementation of the IRPC concept will use three levels of technology. The sequential use of various technologies
Figure 1. Enabling Technologies
Figure 2. Fully Integrated System
will provide the best characterization of defects in the least possible time:
Scan to provide geometric data in an electronic file.
Scan to identify areas of interest where there is a high likelihood of surface and/or sub-surface defects.
Detail scan areas of interest to finalize characterization of defects.
Multiple technologies were evaluated at each level. Downselection led to the identification of the most appropriate technology for each level. The Level 1 digitizing technology was identified as the T-Scan laser scanning technique from Steinbichler. The Level 2 technology for global defect area identification was identified as shearography from Steinbichler. The Level 3 technology for local defect characterization was identified as terahertz scanning from Picometrix.
The need for a standard test panel with known defects to properly evaluate and downselect from the technologies for finite defect recognition was identified. Both single layer and dual layer standard test panels were designed for this purpose and manufactured for use within the project.
A technology and associated hardware from Moister Register for identification of moisture in the composite structure that could be seamlessly integrated into the IRPC was identified and demonstrated (Figure 3).
The IRPC concept includes operator intervention for tasks where automation is either impractical or simply more effectively performed manually. Laser projection was identified as a technology that could be integrated into the IRPC to display results to operators on the Radome surface and serve to control and validate the manual operations. LASERGUIDE from Assembly Guidance Systems was selected as this technology. Due to its immediate application potential a LASERGUIDE unit was demonstrated. Basic training in use of the unit has been provided to Warner Robins ALC with the goal to implement the system into existing operations.
Exposure to the IRPC concept has been broadened to include both commercial and military potential users. Many of these new potential users have participated regularly in the weekly teleconferences. Active participation in the form of identification of broader requirements to meet industry repair needs has been provided by these new participants making the IRPC concept more universally applicable. The IRPC project through this process has spawned an ongoing activity in composite repair, the Consortium for Improving/Integrating Advanced Composites Processes (CIACP) led by the GFM organization.
Critical to achieving the vision of the IRPC was the ability for the various technologies to work in an integrated fashion. While much software development will be required to achieve
Figure 3. Identifying Moisture
integration in an automated sense, the final demonstration made by GFM showed that functionally the separate technologies could work in harmony. Further, the notion of a machine tool based coordinate system enables the individual technologies to work sequentially in a seamless fashion on a once-tooled pallet platform.
The benefits realized by the implementation of the IRPC are many. Several of these benefits relate to the overall impact of supply chain issues. Regarding Radomes in general among the most prominent qualitative benefits are:
Improved repair consistency and precision. The IRPC being a mechanized versus manual repair will perform the repair process against well defined defects in the same way each time.
The Radomes have a typical long service life and are serialized assets within the defense supply chain system. The IRPC captures contour and historical repair data in digital form. This historical data can be easily stored and accessed for future reference.
The historical data can be used to plan and guide future repairs as well as expanding the data base functionality to include records of field repairs.
Precision defect definition and removal provides accurate data for patch preparation increasing material utilization.
Application of LASERGUIDE system provides technicians with instructions for accurately placing patches and proper sequence for repair.