November 2004

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/. To subscribe or unsubscribe to the CTMA Connector, send a message to listserv@listserv.ncms.org with "subscribe CTMANewsletter" or "unsubscribe CTMANewsletter" in the subject line.

This proposal seeks for the development of a handheld Fault and Arc Location Tester (FALT) for aircraft (or other) wiring.  This hardware will be based on spread spectrum fault location methods developed and demonstrated in the Center of Excellence for Smart Sensors at the University of Utah.  While other methods for locating faults on wiring are limited to testing single wires with hard faults when the wires are unpowered, spread spectrum methods are ideal for testing live wires with live loads in their original branched configurations.  This system has been demonstrated for location of both hard faults (opens or shorts) and intermittent faults (both wet and dry arcs) on realistic aircraft wiring bundles with live loads, typically to within 3-6 inches.

Test equipment that can operate on live circuits is critical to the deployment of arc fault circuit protection designed to reduce system damage in the event of an arc fault.  While arc fault circuit breakers are designed to reduce damage due to system failure, they can make system maintenance more difficult than at present because arc faults will be nearly impossible to track down on the ground with current test equipment.  The FALT can be used on live systems to track down intermittent failures such as arc events.

While this development effort is focused on the Navy’s EA-6B aircraft, the test system proposed here has application to other aircraft as well.  This equipment will be designed to reduce maintenance time and effort, allowing the system maintainers to locate certain soft faults (intermittents) as well as the hard faults (open and short circuits) that can be found by currently available test equipment. 

In addition, the proposal includes a handheld wire-tracing probe that will provide the maintainer with a distance-to-fault indicator in their hand as they trace the wire to the fault.  This probe will guide the maintainer to faults indicated by the handheld spread spectrum wire tester, and will work on all types of aircraft, support equipment, etc.  This probe is currently not available on any known test system.  It is particularly valuable for use on the EA-6B and other aircraft due to the present difficulty in tracing faults in the wiring maze inherent in aircraft design.

In this proposal, we will

1. Design and build a handheld spread spectrum time domain reflectometry (SSTDR) wire diagnostic tool.  This will be done in communication with maintenance personnel to assure that the tool is effective, accurate, quick to set up, and easy to use.

2. Develop a user interface for single or branched wiring networks.

3. Develop a data acquisition system, to facilitate data collection for potential future prognostic applications.

4. Develop a handheld wire tracing probe that when used in conjunction with the handheld spread spectrum wire tester will allow the maintainer to follow all or part of the wire to locate the fault on the wire itself, rather than just giving a “distance” to a fault.

Interested participants should contact the NCMS project manager, Lee Patch, leep@ncms.org, 734-995-4972.

Project Participants Requested: Laser Cladding Process Monitoring Sensor (LCPMS) - “Closing the Loop on Laser Process Parameters”

The DoD community continues to extend the life of war-fighter equipment, legacy systems and their components beyond their initial lifecycle expectancy.  This brings a unique challenge to DoD Depots in their mission to service and repair, in order to provide the war-fighter with the greatest capabilities. Conventional methods of repairing metallic components are unacceptable for many applications due to part geometries and material property limitations.

Laser cladding is a new repair process used for the repair of conventionally unweldable alloys in applications that are susceptible to distortion or undesirable material properties due to heat input.  Process control of laser cladding is imperative for consistent and sound repairs, supporting confidence in new repair technologies.  The deployment of laser repair technology is currently impeded by the lack of sophisticated laser head tooling technology and the lack of closed-loop process control. The technology is in its infancy and the development of a robust closed-loop control laser head would greatly expand the number of laser repair applications as well as reduce equipment and deployment costs.

The benefits of using a high powered laser for this process is a two-thirds heat reduction into the substrate material, resulting in virtually no distortion, extremely low dilution and a very small heat affected zone (HAZ) giving superior metallurgical properties.

This proposed project will:

1. Design and manufacture a process monitoring system for laser cladding applications.  Changes in process parameters can result in inferior metallurgical properties in the cladded material or substrate interface and therefore should be monitored in order to control any changes in clad process.

2. Monitor the size and shape of the process melt pool result in different levels of radiation.  Changes in process parameters may be charted by the fluctuations of radiation intensity. The proposed monitoring system will detect differentiating process parameters which effect radiation output.  

3. Monitor the real-time process parameters that will allow for an opportunity during the cladding process to correct parameter inputs, and will ensure the uniformity of process parameters to provide the required metallurgical properties.  This will result in greater confidence in the applied clad and less rework due to inadequate process parameter control.

4. Identify critical process parameters to be monitored in a closed loop monitoring system including; variation in laser power, loss of filler material, change in filler powder composition, filler material flow and velocity, aim of filler material into the melt pool, melt pool size / shape and thermal parameters.

The project will strive to demonstrate the benefits of a closed loop control laser head which will greatly expand the number of laser repair applications and reduce equipment and deployment costs.

Interested participants should contact the NCMS project manager, Chuck Ryan, chuckr@ncms.org, 734-995-4905.

New Project Ideas (click on topics to see descriptions), if you are interested, contact the project manager listed.  We are going to start to gear up new project ideas for submittal in April or May of next year.  Many of these ideas will come from the 2004 CTMA Symposium.  Make sure you look at the Symposium results on the CTMA website (http://ctma.ncms.org) and let us know where you are interested.  We will only work on those projects with the highest level of interest.

We appreciate your feedback. Please contact Chuck Ryan with suggestions or input on other topics that would be of interest to you in this newsletter. The CTMA Program is sponsored by the Department of Defense; the content of this newsletter does not necessarily reflect the position or policy of the government; no official endorsement should be inferred.

Copyright 2004
National Center for Manufacturing Sciences