Continuous Improvement Training Program
A Continuous Improvement Program
Featuring 8-Training Modules by Bill Gaw

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Lean Manufacturing Training Program
Lean Manufacturing Simulation Game 

Changing market conditions often influence the way we manufacture. At the same time, product life cycles can drive the transformation from one manufacturing style to another.

In examining the life cycle of products, one often finds newly introduced products are typically of a higher variety and lower volume until acceptance, or maturity. As products mature and demand increases, the variety may remain at the finished item level. But, there is usually a commonality among lower level sub-assemblies whose volume, but not varieties, will increase, creating the oppor­tunity to change the method of planning and producing these items.

Somewhere down this road we find ourselves facing situa­tions where we are attempting to manufacture in a mixed mode environment, combining batch and repetitive pro­duction, and attempting to fit our software to unfamiliar tasks. This evolution requires changes in planning, orga­nization, and systems. This presentation attempts to point out what may or may not be known to those companies facing this situation.

Recognizing the Change to Mixed Mode

There are many companies, through evolution, rather than revolution, who have changed over to mixed mode manu­facturing and planning strategies, and may not even be aware that this is what they are doing.

This unmanaged evolution can create the misunderstand­ing that when a customer order arrives at a company, we can pull all the BOM parts needed to satisfy the order (including raw material parts) without requiring any in­ventory "lying around" allowing this to happen. This would mean that we can satisfy our customer because we are so synchronized with our suppliers and various work centers that we can respond immediately to demands in lot sizes as small as 1, without anything in the pipeline.

In the real world, this cannot happen. The cumulative lead time required to manufacture most products is longer than a customer will accept for delivery time. With a completely demand driven, KANBAN, JIT system, time is still a factor. Even without setup time to contend with, the more opera­tions required, the longer the lead time will be. So, adopting KANBAN and JIT completely won't work unless there is work in the pipeline (buffer inventory) through all the operations until the final configuration has to be manufactured.

One way of accomplishingthis is to change the way we plan. We can change to a pull system building end products to a signal and backflushing labor and parts, while building subassemblies ahead to a forecast with the historical knowledge that the products will be required. In effect, what we have done is lower the level in the BOM for what they forecast, while configuring end products strictly to what the customer orders.

The Production and Inventory Management System

Fitting a production and inventory management system to meet the unique demands of a mixed mode production environment requires a reasonable understanding of soft­ware tools and implementation strategies. While a variety of standardized or modular manufacturing software appli­cations exist, integrating them to create a mixed mode solution poses a special challenge.

The Master Schedule

The Master Schedule is a plan of production to which a plant is committed at any given time. Inputs to the Master Schedule usually come from either forecasts or actual customer orders. In actual use, a dual function occurs, first as an order launching plan (the Master Schedule) and also as a reactive device (the Final Assembly Schedule).

Raw materials and sub-assemblies require a master sched­ule to allow for the variations in lead time required to purchase, fabricate, or assemble. In addition, capacity constraints require us to plan production based on real capabilities. Because of this, the master schedule or forecast will never disappear. Attempting to get your software to handle two levels of master scheduling has resulted in some firms taking the final assembly off line and reverting to a completely dis-attached system.

One method that will help is to use a "gross simulation" explosion of the forecast and customer orders to report on what lower level components are needed. These are then compared to pre-set reorder levels for the various work cells which produce end items. In this way we can build to plan and assemble to demand. Supply and demand are brought into synch within the manufacturing environment through the coordination of two ordinarily disconnected systems.

To be Continued