Chapter List

Overview

Part confusion in assembly is the primary cause of defects in manufacturing today, and the magnitude of this problem grows as manufacturers implement more and more mixed-flow assembly lines. Many low-technology solutions are available to prevent, make less likely, or quickly detect picking errors, but these techniques are not massively applied. There are also high-technology solutions developed for warehouse distribution applications that can be applied on assembly lines. Although they are far short of full automation, they are orders of magnitude cheaper.

Working our way backwards from the assembly station to the supplier, we examine means of preventing or reducing the likelihood of errors at each point where they may occur. The only way to make an assembly mistake impossible is to standardize product designs around as many common parts as possible and design each product so that only the right parts will fit in the right place. Most plant managers do not have the authority to do this and must live with product designs they have had no input to. They can, however, modify workholding and part presentation devices to make errors less likely, taking advantage of automatic identification (auto ID) technology based on bar codes, ID squares, or radio-frequency ID (RFID) chips.

At the assembly station, kits of parts for different products are more difficult to confuse than individual parts, particularly if the goes-into product ID is clearly marked both on the kit...