Likewise, a machining line of say 15 sequential machining opera- tions, such as drilling, tapping, etc., that are connected by a transfer line between each operation would be shown with only one process box on the door-to-door map, even if some inventory accumulates between machines. (If a detailed process-level map is later made for the machining area alone, then you would draw one box for every indi- vidual machining step.) But if there are distinctly separate machining processes in the plant, with inventory between them stagnating and transferred in batches, then each gets its own process box.
Material flow is drawn from left to right on the bottom half of the map in the order of processing steps; not according to the physical layout of the plant. At Acme Stamping we find six processes in the steering bracket material flow, which occur in the following order:
• Stamping
• Spot-Welding Workstation 1
• Spot-Welding Workstation 2
• Assembly Workstation 1
• Assembly Workstation 2
• Shipping