Volume 03, Issue 7
|Letters to the Editor|
-Tom Walton, Everett, Wash.
-Michael Monaghan, Auburn, Wash.
What's up with Boeing? Why aren't we the people building the first commercial spaceliners?
I know it's a small market, but I think we're missing on a huge prestige item here. We let Airbus move ahead of us in airliners, are we now going to let Mojave Aerospace Ventures [which funded the development of SpaceShipOne] best us in the spaceliner launch? Would Bill Boeing have let an upstart company beat us? I think not. I think it's time Boeing grabbed a few headlines by showing people Bill Boeing's company is still out there.
-Richard Bamberg, Huntsville, Ala.
It concerns me that our own Boeing Store uses Federal Express for merchandise delivery. Although Federal Express is a great company, we should ask how many planes have they bought from Boeing in the past 10 years. Could our packages be flying on an Airbus jet? Or when our fellow teammates take business trips: Are they on a Boeing airplane or an Airbus jet? The same applies to intracompany correspondence: Are we using companies that fly Boeing or Airbus?
The employees, retirees, vendors and families of this great company have a lot of muscle and financial clout. We should use that clout to contribute to the success of those who support us.
How long would it take for the word to get out that a half million, or even a million, Boeing employees, retirees and suppliers refuse to fly or send their parcels on anything but one of our magnificent planes? After all, one only has to ask themselves this: If you built Ford cars, would you drive a Chevrolet? I think not. My challenge to Harry Stonecipher and the people of Boeing is this: We generate enough travel throughout our corporation to support a fairly large airline. Let's take care of those that take care of us.
-Donald Edgerton, McAlester, Okla.
-Steve Evans, Foothill Ranch, Calif.
I am wondering if FSW passed all the required stress and fatigue tests. If we in Wichita, Kan., choose to use this process, do we need to have additional FAA certification? Has the pending certification of the Eclipse business jet airframe made it an easy passage for all aircraft to switch from riveting to FSW?
-Joan Holup Wichita, Kan.
Raj Talwar, Boeing manager of Metallic Processes in Phantom Works, replies:
Even though FSW is a simple process and requires only a few variables such as tool-rotational and travel speed, we have been working for the last several years in advancing the design of the FSW tool. Every time you change the tool design or change the aluminum alloy or the type of joint or the joint thickness, the weld properties change. So we have been working on a point design for a specific application, alloy, tool and thickness. Bottom line: We have both static and fatigue properties of commonly used aerospace alloys. It is sometimes difficult to compare welded joint properties with riveted joints, so we have been comparing welded joint properties with the base material properties.
Wichita has decided to implement friction-stir welding on the 747 cargo barrier beams and asked FAA to approve the process for use on this application. Wichita has a machine in-house and this machine will start fabrication of the production hardware soon.
The use of friction-stir welding on Eclipse aircraft does make it easier for Boeing to implement the process on Boeing products. Eclipse aircraft have lower stresses and lower fatigue life requirements. Implementing this process on the primary structure of Boeing aircraft will still require Boeing to demonstrate joint properties, process robustness and corrosion properties, and validate non-destructive testing techniques.
In addition, John Schlaerth of El Segundo, Calif., asked several questions. Following are his questions, along with Talwar's answers.
Q. What is the thinnest and thickest base metal considered acceptable for joining?
A. Thin material is around 0.020 inch and thick is around 3 to 4 inches.
Q. What is the minimum width of material required on either side of the 5/8-inch weld-head joint?
A. Around 1/8 inch on either side. Total width is likely to be around 1 inch.
Q. Compared to the base material, what is the weld strength in percent?
A. It varies for various alloys and weld-joint thicknesses. In general, the loss of strength is around 20 percent (compared to the base material).
Q. Is this process scalable? That is, how small could the friction-stir tool effectively be made?
A. Yes. We have made a fairly small tool to weld a 0.020-inch thick satellite panel. We commonly use a weld tool with a 0.44-inch-diameter shoulder and a 0.18-inch-diameter pin.
Q. What compressive force must be applied to the weld-tool shoulder?
A. Again, the compressive force required is a function of the material, alloy, joint type, thickness and weld-tool design. For welding through 0.125-inch top skin (lap joint) the force required is around 1,100 to 1,500 pounds. For welding a 1-inch-thick butt joint, the force required is around 5,000 to 8,000 pounds.
Q. Are there any surface-finish requirements for the metals to be joined?
A. Not really. We can weld a joint in load control or in position control. If the surface is rough, then welding with constant vertical forging load helps. But if the surface is rough, then you will get more flash (upset material).
Q. At what RPM range does the welding tool operate?
A. Larger tools operate at 200 to 400 rpm. Smaller tools operate at 800 to 1,400 rpm. When the tool diameter goes down, we need to spin the tool faster to generate heat. In addition to rotating the tool slower or faster, we can also decrease or increase the weld (travel) speed. We don't want to make a cold or hot weld.
Cold welds result in weld defects, and hot welds result in blistering and may create lower properties. Typically the process window is quite large, which makes this process a robust process.
-John Clayborn, Mesa, Ariz.
|Contact Us | Site Map| Site Terms | Privacy | Copyright|
|Copyright© Boeing. All rights reserved.|