Despite the high level of automation in this factory, many of the workers I saw were performing one operation. They fed the pullers for a different kind of zipper into a device connected to another vibrapot containing sliders, while the device put the sliders and pullers together. Of course, I asked, “Why do some zippers have fully automated assembly processes, whereas others are semiautomatic?”
The answer, it turns out, is very subtle, and it boils down to shape.
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That tiny tab allowed gravity to cause all the pullers to hang in the same direction as they fell into a rail toward the left. The semiautomated zipper design doesn’t have this tab; as a result, the design is too symmetric for a vibrapot to align the puller. I asked the factory owner if adding the tiny tab would save this labor, and he said absolutely. At this point, it seemed blindingly obvious to me that all zippers should have this tiny tab, but the zipper’s designer wouldn’t have it. Even though such a tab is very small, consumers can feel the subtle bumps, and some perceive it as a defect in the design. As a result, the designer insisted upon a perfectly smooth tab, which accordingly had no feature to easily and reliably allow for automatic orientation.
I’d like to imagine that most people, after watching a person join pullers to sliders for a couple of minutes, would be quite content to suffer a tiny bump on the tip of their zipper to save another human the fate of manually aligning pullers into sliders for eight hours a day. Alternatively, I suppose an engineer could spend countless hours trying to design a more complex method for aligning the pullers and sliders, but there are two problems with that:
- The zipper’s customer probably wouldn’t pay for that effort.
- It’s probably net cheaper to pay unskilled labor to manually perform the sorting.
This zipper factory owner had already automated everything else in the facility, so I figure they’ve thought long and hard about this problem, too. My guess is that robots are expensive to build and maintain; people are self­replicating and largely self­maintaining. Remember that third input to the factory—rice? Any robot’s spare parts have to be cheaper than rice for the robot to earn a place on this factory’s floor. In reality, however, it’s too much effort to explain this concept to end customers; and in fact, quite the opposite happens in the market. Putting the smooth zippers together involves extra labor, so the zippers cost more; therefore, they tend to end up in high­end products. This further enforces the notion that really smooth zippers with no tiny tab on them must be the result of quality control and attention to detail.
My world is full of small frustrations like this.

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