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Unformatted text preview: To demonstrate, let’s look at a simple case of a single-tool factory, with no downtime or rework. Product A requires 1 hour per wafer on the tool; Product B requires 2 hours per wafer. With a 50/50 mix and a total of 16 wafers per day, total required production time is (8)(1) + (8)(2) = 24 hours—so we have just enough capacity. But if product mix shifts to 25% Product A and 75% Product B, total required production time is (4)(1) + (12)(2) = 28 hours, and we have insufficient capacity, even though total production volume has remained unchanged. Expand this example to include a dozen or more constantly changing products and hundreds of tools, and we have the real world…and a threat to capacity that is immensely complicated to answer. This is a concern for Headway Technologies, a manufacturer of leading-edge read-write heads. A readwrite head is a tiny integrated circuit, about the size of a grain of pepper, that magnetically reads and writes data onto and off of a disk in a disk drive. Heads are manufactured in the form of wafers, each consisting of 15,000-20,000 identical heads, each containing many layers of microscopic c...
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- Spring '11