Assembly Cells
An excerpt is available in .pdf format from Lean Assembly by Michel Baudin, dealing with the issues of assembly cells and assembly lines, plus the book''s full table of contents, bibliography, and index. Click here to read the excerpt.
To obtain Adobe Acrobat Reader, click on the link below.
Assembly Automation
Automation is discussed in the book, but not as an independent subject. The discussions of automation are woven through the other topics. The key points are as follows:
1. Assembly line work is unpopular with operators. It can be made safer, more secure, and less tedious, but not into what children dream of doing as adults. Over decades, these jobs will be automated, and the challenge is to manage this gradual process in a way that assemblers can support, that is incremental enough to work by attrition, and that provides assemblers with opportunities for professional growth.
2. The ultimate goal is not to completely remove people from factories but to restrict their interventions to tasks that require their special abilities, such as programming equipment controllers, maintaining the equipment, and planning/scheduling production.
3. Any change that reduces the need for human intervention in production qualifies as automation, regardless of the technology employed. Conversely, if the implementation of a high technology approach results in using more people rather than fewer, then it does not qualify as automation.
4. The lean approach to assembly automation is incremental and focused first on jobs that are dangerous, dirty, unpleasant, or error-prone. Many semi-automatic devices are used, including powered hand tools on balancers, "nagara" fixtures that follow a moving assembly line through an operation and provide fixed relative positions for tools with respect to the workpiece, "nagara" switches that integrate the control of equipment start with the planned movement of the operator between stations.
5. There are many different concepts in use, depending on circumstances, including the following:
- Chaku-Chaku lines. Click here to view .pdf presentation. The concept applies to both machining and assembly.
- T. Fujimoto uses the term "in-line mechanical automation" to describe the approach Toyota implemented in the 1990s (See bibliography in the attachment).
- In mass customization environments, such as desktop computer assembly at Dell, the focus of automation is on the picking, transportation and delivery of kits to manual assembly stations (See Industry Week''s Best Plants of 2001).
- Auto ID technology, including bar codes, ID squares, and RFID tags, plays a key role in the prevention of picking errors, which is the dominant cause of quality problems in assembly.
6. In a mixed flow assembly line, using a higher level of automation for the more complex products is one of the strategies used to ensure that all products have matching assembly times at each station.
7. Single piece presentation is a strategy in which one and only one unit of each item is presented to the assembler with its smallest dimension facing out, in such a way that, once it is picked, the next one falls into place automatically and replenishment takes place from behind the line. This strategy simplifies assembly automation because the parts are always presented at the same location in the same orientation.