One of the unique and valued tenets of the Toyota Production System (TPS) is the ability to manufacture products on a just in time (JIT) basis. Why do this? In addition to being able to respond to customer’s requirements more quickly, using JIT enabled Toyota Industrial Equipment Manufacturing (TIEM) to improve quality by responding quickly to any problems (opportunities), minimize inventory and space usage, respond to any engineering changes, and eliminate waste..
When trying to figure out how your organization can build a sequential JIT flow, perhaps some of the concepts we used in this illustration might be helpful. Keep in mind that we present these drawings and discussions not as “how to guides” but simply as “ideas” to help start you thinking process.
JIT enabled TIEM to improve quality by responding quickly to any problems (opportunities), minimize inventory and space usage, respond to any engineering changes, and eliminate waste. During the early days of TIEM this was accomplished not by “batch” manufacturing and “batch” parts sourcing, but rather “sequential” manufacturing and “sequential” sourcing of parts from its’ sub-assemblies or suppliers as shown in the attached graphic entitled “In Process Inventory Chart”. These sequentially resourced parts were each scheduled for either machining, painting, sub-assembly, or sequential staging according to the main assembly line scheduled model configuration (Mfg. Instruction) and sequence needs. Such a scheduling through the main assembly line from the low to the high number (left to right on the attached diagram), you can see how we built or sourced material in the scheduled sequence to enter the assembly at various appropriate points during sub-assembly or assembly.
Inevitably, a scheduled sequence might require change due to a missing component, a customer need change, a processing difficulty, etc. In such a case, we used the rescheduling approach described on the attached page entitled “Revise In-Process Inventory Procedure” to discuss at the Group Lead (GL) & Team Lead (TL) levels exactly what scheduling changes needed to be made, followed by issuing a revised in-process inventory chart.
Yes, they are approximately 29-year-old drawings, but the approach worked then, and the concept works much the same today regardless of the product being manufactured/processed. Today, at TIEM, the process and feeder processes have become increasingly more complex as new models and required sub-assemblies have been developed! Regardless, the process approach will remain the same or very similar. If you are hesitant to move away from “batch processing and assembly”, perhaps start with a small process line with sub-assemblies and build from there as your confidence grows. Remember, “learn by doing”! If your effort is not perfect, improve on it by learning!