IL THE PRINCIPLES OF MASS PRODUCTION As to shop detail, the keyword to mass production is simplicity. Three plain principles underlie it : (a) the planned orderly and continuous progression of the commodity through the shop; (b) the delivery of work instead of leaving it to the workman's initia tive to find it ; (c) an analysis of operations into their constituent parts. These are distinct but not separate steps; all are involved in the first one. To plan the progress of material from the initial manufacturing operation until its emergence as a finished product involves shop planning on a large scale and the manufacture and delivery of material, tools and parts at various points along the line. To do this successfully with a progressing piece of work means a careful breaking up of the work into the sequence of its "operations." All three fundamentals are involved in the original act of planning a moving line of production.
This system is practised, not only on the final assembly line, but throughout the various arts and trades involved in the com pleted product. The motor car final assembly line offers an im pressive spectacle of hundreds of parts being quickly put together into a going vehicle, but flowing into that are other assembly lines on which each of the hundreds of parts have been fashioned. It may be far down the final assembly line that the springs, for example, appear, and they may seem to be a negligible part of the whole operation. Formerly one artisan would cut, harden, bend and build a spring. In 1939 the making of one leaf of a spring was an operation of apparent complexity, yet was really the ultimate reduction to simplicity of operation.
second workman takes the pieces from belt conveyor and places them on conveyor which passes through the furnace (in which temperature is automatically controlled) ; thence they are deposited at a certain temperature by this conveyor at the unload ing end of the furnace. (3) The heated piece is lifted with tongs by a third operator and placed in a bending machine which gives the leaf its proper curve and plunges it in oil, the temperature of which is maintained at a definite degree by apparatus beyond the operator's control. (4) As the bending machine emerges from the oil bath, the same operator removes it to a conveyor that delivers it to an annealing furnace. (5) A fourth operator places the leaf on a conveyor that passes through the annealing furnace. (6) The same workman sends it by conveyor through a water-cooling bath, thence to the spring assembly line.
As a set of springs on the Ford car requires on an average 14 leaves, and 25,00o springs are a normal day's output, this operation must be visualized as employing a great battery of lines similar to the one briefly described.
As all the leaves in a spring are of different length and curve, from the bottom or master leaf to the top leaf, this operation must be visualized as one of many carried on simultaneously by differ ent batteries of machines, each battery working on its own special size. All of these lines, with their various machines and opera tions, are converging on the point where the leaves are assembled into springs. The leaf whose progress has been described is the simplest one.
The operation proceeds as follows: (7) A fifth workman removes the leaf from the conveyor on its arrival at assembly line. (8) A sixth workman sprays the arriving leaves with a lubricant. (9) A seventh workman inserts a bolt through leaves assembled as a spring. ( o) An eighth workman puts a nut on the bolt and tightens it. (11) A ninth workman puts in the clip bolts and tightens them. (12) A tenth workman inspects the completed spring. (13) He hangs spring on conveyor. (14) Conveyor carries it to loading dock where the eleventh workman removes it.