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It's only 15 in. in diameter and 12 in. tall, but it weighs 280 lb.
It's a cap made of heavy armor steel. It sits atop the gun turret of an Army tank to protect the infrared imaging equipment inside.
Even more substantial than its physical weight is the significantly better way of designing products that the cap embodies.
Specifically, the "armor cap" is a high-quality, innovative piece of equipment that will be produced at lower cost, with more functions, faster -- because it was created using concurrent engineering and the right technology.
Texas Instruments Inc.'s (TI) Defense Systems & Electronics Group, Dallas, had to meet some challenging functional requirements for this product. Along with providing ballistic protection, the cap rotates 360 degrees so that the tank can shoot on the move. Consequently, it had to be well-balanced.
Normally this equipment is all fixed, says Dick Gall, engineering manager. Balancing this rotating cap ensures that it stays aligned with the gun even in the pandemonium of battle.
A computer-aided engineering tool known as 3-D solid modeling was indispensible in meeting those requirements, says Bob Coburn, the mechanical engineer who was assigned to the project.
"The center of gravity of the cap had to be within 75 one-thousandths of its axis," he says. "That's a very tight requirement" (a little more than a 16th of an inch).
The opening in the cap, which allows the infrared equipment to see out, put the center of gravity off the axis by about half an inch, says Mr. Coburn.
Adjusting that was no problem. By using Parametric Technology's Pro/ENGINEER solid modeler, Mr. Coburn created a 3-D computer model, experimented with counterweights on the cap, and balanced it even better than required.
Running between 20 and 30 variations of counterweights took only...