DoD maintenance facilities possess a wide variety of metalworking capabilities with multiple welding techniques. Many of these welding processes, and the associated inspections and training, are applicable to numerous weapons platforms and have many commercial industrial applications.
Some of the welding technologies used by DoD include:
- Gas metal arc welding-pulse (GMAW-P) – a technique that uses a pulse current which reduces the required heat input, giving welders better control of heat when welding on hard materials;
- Electron beam welding – precision welding that uses extremely high energy density to minimize the impact of the heat by producing a small heat-affected zone;
- Heads-up-display (HUD) welding – a real-time analysis of the welding process that provides instant feedback in the operators’ helmet, reducing costly repairs and rework of welds;
- Laser welding – a high-speed welding capability for carbon steel, stainless steel, aluminum, titanium, and dissimilar metals.
This forum will discuss some of the welding techniques/technologies being employed in DoD maintenance depots to reduce costs and increase weld reliability, and also describe the associated inspection processes and training programs. Please join us and participate in the exchange of information and ideas.
Event: On 30 August, 2016, the Joint Technology Exchange Group (JTEG), in coordination with the National Center for Manufacturing Sciences (NCMS), hosted a virtual forum on “Welding Training, Inspection & Operations”.
Purpose: The purpose of the forum was to discuss ongoing DoD efforts towards DoD welding training, inspection capabilities, and welding techniques/technologies being employed in DoD maintenance depots to reduce costs and increase weld reliability.
Welcome: Greg Kilchenstein (JTEG Co-Chair), welcomed everyone to the forum, thanked the presenters and all the listeners for their attendance, briefly described the purpose of the JTEG technology forums, and highlighted the importance of welding operations, inspection and training in the DoD maintenance community.
Administrative: This was an open forum. The presentations, along with questions and answers, were conducted through Adobe Connect. A separate audio line was used. Approximately 35 participants from across DoD and industry joined in the forum.
Naval Aviation Fleet Training – Mark Sapp (NAVAIR) described the NAVAIR welding training program, beginning with the requirements flow, schools, and student learning objectives. He also compared the program with USAF welding training, and concluded with a description of some of the welding equipment used.
Induction Thermography and its ability to find near-surface cracks in metals – Patrice Lockhart (NUWC NWPT) defined Induction Infrared Thermography (IIRT) as a Non-Destructive Testing and Evaluation (NDT&E) technology that can rapidly detect flaws (cracks, debonds, voids) in electrically conductive materials (metals) without the need for hazardous materials or post inspection cleaning steps. He compared IIRT to other technology to include dye penetrants, pointing out that IIRT can reduce maintenance costs by noninvasively detecting serviceable defects as a potential replacement for PT and MT on metals that is also faster with no hazardous materials or post-inspection cleaning steps.
THz Imaging’s ability to locate weld seams through VA-Class hull – Patrice Lockhart (NUWC NWPT) described THz Imaging as using electromagnetic wave technology, similar to the TSA airport passenger scanners, to detects bubbles, delamination, corrosion, pitting, layered surfaces, and material non-uniformities (including water intrusion). THz works well with ceramics, epoxies, urethanes, and some rubbers, and can reduce maintenance costs by noninvasively detecting serviceable defects.
Deformation Resistant Welding – Jim Richter (GraviKor) discussed “Bringing NASCAR Spaceframe Technology to Military Vehicles”. Spaceframes can provide military ground vehicles with: weight reduction, upgrade abilities, improved safety and survivability, rollover & blast protection, reduced total ownership costs, and reduced maintenance costs. However, cost and quality have been major impediments to spaceframe adoption. Deformation resistance welding (DRW) dramatically reduces the cost to manufacture lightweight spaceframes.
Closing Comments: Greg Kilchenstein thanked the presenters for their contributions and the audience for their participation. He commented on the quality of the presentations and the great variety of capabilities discussed by the presenters.
Action Items:
1) Obtain “public Release” versions of the presentations and post to the JTEG website. These meeting minutes, the Q&A, and those briefing slides approved for public release, will be posted on the JTEG website at https://jteg.ncms.org/ . (All presenters, LMI, NCMS)
Next JTEG Meeting: The next JTEG virtual forum is 27 September, 1:00 – 3:00 pm EST. The topic is “Asset Visibility; What, Where, and Condition”.
POC this action is Ray Langlais, rlanglais@lmi.org , (571) 633-8019
Naval Aviation Fleet Training
Mark Sapp (NAVAIR)
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Q1. Are our welding instructions based solely on AWS specs or are there other SDOs i.e. EWI that we leverage for our instructions?
A1. Yes, we use all that is possible. Requirements are placed to show and state that we need industry standards. More details are used from owner manuals and additional information delivered by the manufacturers.
Q2. Who manages the tri-service welding manual? Is there an active tri-service welding WG?
A2. There is not a formal work group. Most of the collaboration is from informal phone conversations. There is no funding to support travel.
Q3. Do each of the military services have their own training program? …or do they generally leverage NAVAIR’s?
A3. The USAF sends their airmen to technical school after basic where they learn machining and welding. While at the unit they become a journeyman and after 18 months of OJT they become certified.
Q4. Does NAVAIR use any virtual or simulation based training tools to assist in training welders?
A4. North Island is trying to get that capability for MIG welding. It is very expensive, about $200K. Virtual is only realistic for mig welding due to the value received from OJT in other welding.
Q5. Can you discuss the process that you use to certify the weld repairs that are performed on aircraft?
A5. Yes, we weld repair based on the OEM permissions in the technical manuals.
Q6. RK: Slide 4 – The Marine Corps is looking to have O level Titanium welding capability for cracks. Is there a known capability? Is this feasible? What are the requirements for titanium welding?
A6. NAVAIR used to have titanium, magnesium, and cobalt, but not currently. However, we are looking. Titanium requires extra cleanliness. We teach civilians the difference between “glovebox” and open atmosphere and how to accomplish the gas shielding process. (Mark then described the cooling process and equipment.)
Q7. Akin to the V-22 welding initiative, is there any F-35 applications that require further development and training?
A7. At the depot and OEM level
Induction Thermography
Patric Lockhart (NUWC NWPT)
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Q1. How big of an area can be covered and how fast?
A1. We are actively working in that area. Unfortunately, the number will change each time it is asked due to the many variables. The type of material is also a major factor.
Q2. What are the detection limits (crack size) of this technology? Can it be performed robotically?
A2. We are still working that. It is difficult for us to get crack samples. We often have to make our own, and haven’t run across any crack that we haven’t been able to see. We believe it should be possible to do robotically and are working toward that capability.
Q3. Can this process see thru organic and inorganic coatings?
A3. It is very sensitive. I didn’t expect it to, but we haven’t performed that study yet.
Q4. Is Induction Infrared Thermography (IIRT) much faster and more accurate than traditional dye penetrant inspection?
A4. Faster, yes. See slide 5. We can do 10 inches of weld in 6 seconds. The more accurate question is more difficult to answer. The defect size matters a great deal.
Q5. Does the system software help the inspector find the cracks or is it dependent on the “calibrated eyeball”?
A5. We use COTS software and it does not do that. I think we can do it though.
THz Imaging
Patric Lockhart (NUWC NWPT)
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Q1. Does this technique supplement or supplant Phased Array Ultrasonic inspection?
A1. You can use this on different material. Phased Array can be used on metals, THz cannot. THz can do acoustic sampling. Phased Array cannot. There is also an overlap where one works better and it is material specific.
Q2. Are there any operational health concerns using THz Inspection?
A2. No. It is commonplace to cut the beam with your hand. The technology is actually used for crowd control in a much higher power version. The energy levels are in microwatts, which is much too low to cause health concerns.
Deformation Resistance Welding
Jim Richter (GraviKor)
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Q1. Has whole body vibration been reduced with the use of this technology?
A1. Yes. It is a much more rigid platform. Racing has that same issue.
Q2. What is the status of the effort with the USMC truck cab redesign?
A2. We are delivering the 1st prototype to them right now. You can see it at MCB Quantico from Sep 27-29 during the “Modern Day Marine” Military exposition.