modernizing welding capability

Operated by Los Alamos National Security, LLC for the U.S. Department of Energy's NNSA

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Modernizing Welding Capability

Paul F. Moniz1, Stanley Pierce1, Jesse N. Martinez2, John L. Brown2, Edwin M. Serrano2, Alan Hoff2, Andrew Thronas2, and Benny Rose2

1Manufacturing Engineering and Technologies, Actinide Engineering and

Science and 2Nuclear Component Operations Heat Source Technologies

LA-UR-15-21288


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Purpose The Los Alamos Actinide Engineering and Science team uses automated Gas Tungsten Arc welding (GTAW) processes to encapsulate plutonium oxide into various container configurations and materials. Materials used in the encapsulation and packaging processes are alloys of Iridium, Platinum, Cobalt, Tantalum, and Stainless Steel.

Welding is a critical part of the manufacturing process, and robust control of the process is essential in providing a safety class container that can be handled outside a controlled environment, and meet stringent safety and performance requirements during launch and space operation.

Slide 2


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Current Welding System • The current welding system uses a DOS based computer to control

welding current and travel speed. Simplistic electro-pneumatic controls are used for weld torch coarse positioning. Fine adjustments of the torch are accomplished by the operator manually adjusting hand screws. These fine adjustment create system variability from operator to operator.

• The single most important variable created is “arc gap”. This is the gap between the electrode tip and the work piece or part to be welded. The operator variability can be as much as 0.004”.

• The current system can not compensate for changes in the arc gap caused by run out in the fixture/tooling which has been as much as 0.008”. This compounded by the operator variability can be extremely problematic in welding processes with arc gap sensitivities such as welding Iridium.

Slide 3


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Slide 4

Why Modernize – The current systems are obsolete and spare parts are

no longer available. – Current systems have limited control functionality. – Process improvements are needed.

• Square wave pulse control technology. • Apply additional engineering controls on the process mitigating

variability. • Computer controlled servo motion. • Engineering controls.

– Standardization • Training and Qualification. • Interchangeable spare part inventory.


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Slide 5

DoE 3

Magnetic oscillator3

DoE 14 DoE 6

Manual slides Gas operated slide

Control Pendent

Welding power supply


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Slide 6

DoE 18 DoE 18

DoE 3 DoE 15 Corrosive affects of PuO2


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Slide 7

This system is over 20 years old.


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Slide 8


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Slide 9


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Slide 10


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Slide 11

Process Improvements – Updated system controls.

• Linux based operating system with digital signal processing (DSP).

• Interchangeable motion control modules.

– Motion Control. • X and Z axis electromechanical computer controlled slides. • Choice from either arc voltage controls or software

functionality to mitigate arc gap changes caused by part run out.

– Spare parts are readily available.


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Slide 12

Capabilities – System controls

• Linux based operating system with digital signal processing (DSP).

• Servomotor motion controls (X,Z and Rotation). • Control of non servo actuated motion systems. • Interchangeable motion control modules.

– Fully integrated Miller welding power supply. • Pulsed or constant current.

- Maximum pulsing frequency of 500 Hz. • Magnetic oscillation.


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Slide 13

Capabilities Cont. – Applied engineering controls to variables.

• Software applets. - Linear welding motion control. - Rotational welding control. - Virtual position control. - Wire feed pulsing control. (dabbing)

• Data acquisition up to 10 Hz. • X and Z axis servo mechanical computer controlled slides.

- Programmable positioning. – Full positional control and offsets.

- Programmable torch touch retract. • Motion Controls

- Achievable motion controls in the X & Z directions to the 0.001”. With repeatability of +/- 0.0005”.


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Slide 14

R² = 0.7949

R² = 0.999

0.030

0.040

0.050

0.060

0.070

0.080

0.090

10.80 11.00 11.20 11.40 11.60 11.80 12.00 12.20 12.40

Bead

Width Inches

Average Amps

Affects of Arc Gap and Power changes on Bead Widths

.024 face width

.024 root width

.030 face width

.030 root width

.036 face width

.036 root width

Arc Gap


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Slide 15

Without Virtual Alignment

Part

Perfectly Centered

Electrode

Arc Gap


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Slide 16

With Virtual Alignment

Part

Perfectly Centered

Electrode

The ability to correct for run out is essential in controlling weld bead widths.

Arc Gap


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Slide 17

95 100

The packaging and sample welding systems are the most recent upgrades with the AMET XM technology.


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Slide 18

9516 Shipping Package Welding System.

This system is over 20 years old.


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Slide 19

Challenges in High Hazard Environment – Scheduling – Conduct of Engineering – Configuration Management – Performing work in a plutonium glove box

environment. • Ergonomics • Maintain containment of plutonium contamination. • Plan for success.

- Identify and pre-stage all tools needed to perform the work. - Identify hazards. i.e.; sharp edges, corners for components and

tools that might damage the glove box gloves. Mitigate as necessary.

- Identify the appropriate personnel to perform the work.


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Slide 20

modernizing welding capability

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