Assembly line

An assembly line is a manufacturing process (often called a progressive assembly) in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in sequence until the final assembly is produced. By mechanically moving the parts to the assembly work and moving the semi-finished assembly from work station to work station, a finished product can be assembled faster and with less labor than by having workers carry parts to a stationary piece for assembly. Assembly lines are common methods of assembling complex items such as automobiles and other transportation equipment, household appliances and electronic goods. Workers in charge of the works of assembly line are called assemblers. Assembly lines are designed for the sequential organization of workers, tools or machines, and parts. The motion of workers is minimized to the extent possible. All parts or assemblies are handled either by conveyors or motorized vehicles such as forklifts, or gravity, with no manual trucking. Heavy lifting is done by machines such as overhead cranes or forklifts. Each worker typically performs one simple operation unless job rotation strategies are applied. According to Henry Ford: The principles of assembly are these: (1) Place the tools and the men in the sequence of the operation so that each component part shall travel the least possible distance while in the process of finishing. (2) Use work slides or some other form of the carrier so that when a workman completes his operation, he drops the part always in the same place—which place must always be the most convenient place to his hand—and if possible have gravity carry the part to the next workman for his own. (3) Use sliding assembling lines by which the parts to be assembled are delivered at convenient distances. Designing assembly lines is a well-established mathematical challenge, referred to as an assembly line balancing problem.