ABSTRACT
A manufacturing cell is a collection of machines and robots that performs a specific function, such as manufacturing a family of parts, and is the basic structure for a cellular manufacturing system (Black, 1983; Black, 1988; DeGarmo et al., 1988). Recently, there has been a great emphasis on how to design and control a manufacturing cell, but safety considerations have often been overlooked. The safety guarding in such a system can be classified into two levels-the individual machine level and the system level. At the individual machine level, safeguarding devices are used to prevent contact with dangerously moving parts (OSHA, 1982), to prevent human errors and to protect humans from ejected objects. At the system level, consideration is given to the interactions between the machines and the manufacturing process performed in the cell. Robots are relatively new machines designed for automating a manufacturing process, serving as a material-handling device or as a process-assisted (e.g. painting, welding, and drilling) device. It may be questioned if a robot can be treated as traditional machinery, but a review shows that most of the guarding principles for traditional machines are still applicable to industrial robots (Liou et al., 1989). For robot guarding, there are many
guidelines and standards available in the literature (JISHA, 1983; Bonney and Yong, 1985; National Safety Council, 1985; RIA, 1987; Verein Deutscher Ingenieure, 1987). Table 8.1 shows the definitions, descriptions and application examples of various guarding techniques (NIOSH, 1975; MTTA, 1982; OSHA, 1982; Strubhar, 1984; Robinson, 1985; Etherton, 1988).
