Applications

for Aerospace, Aeronautical, Aircraft,
Medical and Power Generation Systems

GTC was drawn into FSW technology by our involvement in a project for the Lawrence Livermore National Laboratory National Ignition Facility. We needed a high-integrity, low distortion technique of joining 5/8” aluminum plate and extrusions to replace a casting. In order to do this task on time and within budget, we developed a panel-welding machine specifically for this application. This novel approach reduced the project costs by approximately a million dollars after sharing the savings with the customer. The welding machine was based on the simplest and most straightforward design that would perform the job, and was even built from “scrap” material from another project.

General Tool leveraged that experience to win a competitive bid for the contract to build the Universal Barrel Tools and process development/trainer tool for Lockheed-Martin Michoud/NASA. This machine design represents the other end of the complexity spectrum from the in-house panel machine. These tools weld barrels up to 20’ long (plus a 20” test panel in line with the barrel). The integral clamping system develops 162,000 lbs. and the process loads approach 20,000 lbs. The control was required to maintain an accuracy of +/- .001” under load for the retractable pin tool. This accuracy was achieved by a combination of careful detail design, “Force Balance” offloading of the machine structure/ coordinate system of the clamp and process thrust load, and mapping of the anvil deflections under the nominal clamp and weld process loads. In addition, GTC proposed and developed an innovative system to measure the length of the RPT pin, independent of the process force compression and the thermal expansion of pin as process heat wicks up the length. (Both the RPT measurement system and the force balance system are US patent pending) This project has been so well received by the customer that a “NASA Program Star” has been awarded to the General Tool Technical Leader of the project. The specification accuracy has been achieved, at least to the ability of the checkout team’s ability to measure it. Both the shoulder and RPT pin are controlled by either a force or displacement plunge strategy, which employs a complex set of adaptive relationships and hard limits.

Barrel Tool Friction Stir Weld Machine

Four-Axis Gantry FSW Machine

In parallel with the development of the LMC/NASA machine, GTC designed and built a general-purpose gantry style FSW R&D machine for Murray Mahoney at Rockwell Scientific. This machine features a manually adjustable inclination angle, and a C axis to orient the plane of the inclination angle parallel with the local general path in the X-Y plane. Since delivery of this machine, GTC has worked with Rockwell Scientific, 2,000 miles away, to significantly modify the machine by quadrupling the horsepower and adding a 3:1 reduction ratio to the spindle drive, and increasing the Z (plunge) force by a factor of two. We have also implemented a water-cooling system to support high temperature welding in hard metals. These modifications allow Rockwell Scientific to extend the application of this machine by developing friction stir processing in a wide range of materials and penetrations. When the machine was initially specified, Rockwell Scientific had generally worked in aluminum with thickness well under 0.25”.

Recently, General Tool Company designed and built a small FSW machine with the intent to demonstrate the process at various industry trade shows. We have gotten a great deal of positive response to this versatile little machine, as many people have not had the opportunity to view the process. After the word is out, we will then be able to put the machine to work in our shop in either a build or repair capacity.

GTC has just completed the design, build, and installation of a FSW machine for the Edison Weld Institute (EWI) in Columbus, Ohio. The new machine is the largest gantry type machine available in North America, with a working envelope of 10 feet by 10 feet by 16 feet. The length can be increased as customer needs require. The machine has a five-axis capability, which will allow the machine to join components with complex curvature. In addition to the FSW features, the machine also features a high speed machining capability to prepare the components for welding and perform post weld finishing operations. The new unit provides EWI with a multi-functional technology platform, and has been installed in a factory setting to develop, demonstrate and transition advanced joining processes for a variety of applications.

Five –Axis Gantry Friction Stir Weld Machine

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