A smaller but well-known aircraft company attempted to implement Lean Manufacturing for their machine shop and subassembly operations. The Kaizen Blitz was their primary approach. They employed consultants  who came in with the usual panoply of edicts and pronouncements:

• Inventory is evil and must be eliminated regardless of all other considerations.

• The primary measure of work-cell performance is throughput time.

• Machine utilization is of no consequence and should be ignored.

• Work-cells must have a straight-through flow for all products.

• Work-cells must have one-piece flow.

• Low-tech, manual machine tools are superior to high-tech NC equipment.

• Lot sizes must be cut drastically.

These edicts apply to many manufacturing situations including this particular manufacturer's subassembly cells. Indeed, the subassembly cells functioned quite well.

Things did not work so well in machining. Here, a very low-volume, high-variety product mix combined with the above beliefs brought the following results:

• One Piece Flow combined with a disregard for equipment utilization resulted in cells that were paced to the slowest operation on each part thus reducing effective capacity.

• Straight-through flow precluded many parts from a particular cell. These inconvenient parts were simply outsourced.

• Since Lean efforts were restricted to Kaizen Blitz' at the cells, no effort was made to provide purchasing the tools they needed to monitor inventories. With many more parts now being outsourced, inventories of purchased machinings mushroomed.

• Failure to adequately implement setup reduction brought even less capacity as lot sizes were reduced.

• Machining cells were initially tied to particular subassemblies rather than families of similar piece parts. This resulted in sub-optimum cells and limited the number of parts available to a workcell. Many cells were starved for work.

• Operations were taken off of NC equipment and replaced by a series of operations on manual machines. The multiple fixtures produced tolerance buildups and created severe quality problems for some items.

• Eventually, so many parts were outsourced and so little produced that the shop could not cover fixed cost. This did not seem readily apparent, however, because of the fixation on throughput time and WIP as the only significant metrics.

The overall result has been layoffs, higher inventories, an unprofitable cost structure, management changes, and severe pressure from the corporate masters.

Other Examples

Is The Kaizen Blitz Right For You?

Kaizen Blitz Overdose

Kaizen & One Piece Flow

Rationalized Workcell Design 

Workcell Design Seminary

Historical Note:

The guiding beliefs discussed here derive from Toyota's JIT starting in the early 1950's. Such beliefs were useful for Toyota and similar manufacturers. They do not apply to all situations. 

A low-volume, high-variety machine shop is one situation where these guiding beliefs do not apply directly.