The necessity of providing the Army with 10,000 muskets at the most competitive price possible ($13.40 each) was the inspiration for Eli Whitney to invent interchangeable mechanical parts in 1799. The use of interchageable parts conserved material and eliminated waste (the definition of “lean”) by enabling any one of a given type of lock, stock, and barrel in the assembly of any individual musket that was being crafted at a given time. Of course, one craftsman built only one musket at a time. This deficiency was not corrected until much later.

For the next 100 years manufacturers primarily concerned themselves with individual technologies, such as steel making or railroad construction. During this time, our system of engineering drawings and modern machine tools developed; and large scale processes became the center of attention for manufacturing. As products moved from one discrete process to the next through the logistics system and within factories, few people concerned themselves with:

• What happened between processes
  
  
• How multiple processes were arranged within the factory
  
  
• How the chain of processes functioned as a system. 
  
  
• How each worker went about a task

Henry Ford finally capitalized on Whitney’s material waste prevention (interchangeable parts) by getting “leaner” in eliminating waste of another extremely valuable manufacturing commodity - time. The process he invented was called “assembly line production”. By having the in-process assembly move from worker to worker automatically, the wasted time of workers moving from product at point A to the next product at point B was minimized. Hence, the assembly line, more waste prevention, and another step toward what we now call Lean Manufacturing (Figure 1-1), emerged. It was said that one could have any color of Model T you desired, as long as it was black, The next step in lean evolution addressed that shortcoming.

Toyota made the next big breakthrough in Lean Manufacturing some 50 years later. Realizing that one type of automobile (or musket) did not fit all applications, multiple models, each needing its own manufacturing line, were set-up in a competitive assembly process. The time wasted in setting up to build different models of the product was another opportunity for eliminating waste in a process that required more than one model of product to remain truly competitive. The Toyota Production System (TPS) resulted, and is often cited as the first true Lean Manufacturing system. The TPS brought with it the fundamental differences between high volume low mix (few set ups as for muskets or Model Ts), and variable volume, high mix (Toyota style) manufacturing.

In the electronics manufacturing service sector, lean manufacturing is a relatively recent advance. In a case study describing the production of electronic test equipment, this meant transforming from a traditional batch-and-queue circuit board assembly process to a continuous flow manufacturing process. The major problem solved by lean manufacturing methods was the reduction in work in process (WIP) inventory that was accumulating at a number of workstations along the manufacturing line, and too many pieces of WIP that required rework to correct defects from initial production. It was estimated that $1.9 million of WIP inventory was tied up in a manufacturing cycle time of eighteen (18) days. A value stream mapping of the original batch process determined that 88% of the entire process did not add any value to the product. One dramatic example of the waste uncovered in production line involved the process for kitting all of components for the 163 possible equipment variations. Many of the parts for a particular variation were only occasionally used, resulting in a scenario where only 102 of the 163 variations were actually built within a six month period. This led to incomplete kits remaining in the staging area, generating idle time, while the program manager waited for delivery of missing components. At one point nearly $800,000 worth of inventory sat in raw materials. Other times, the program manager released incomplete kits to the production floor, expecting a supplier to deliver as promised. Unfortunately the parts did not arrive on time and circuit card assemblies sat unfinished on the line, creating another choke point of accumulating inventory. This resulted in extra trips from the staging area to the line – all instances of wasted time and money. The initial mandate needed to stop this folly was the implementation of a simple rule that the program manager will release a build work-order only when the kits are complete and ready for staging. After this, additional equipment was acquired to convert the manufacturing line to a pull-based continuous flow process with a high sensitivity to overproduction. The initial deployment of the lean manufacturing model reduced WIP from $1.9 million to $0.38 million and cut the manufacturing cycle time from eighteen (18) days to three (3) days. Quality yields increased from 83.9% to 99.7%.

Retrieval of up-to-date product and process documentation can be a terrible waste of time and effort. The goal to eliminate waste (a.k.a. “lean manufacturing”) demands “paperless” manufacturing. A modern, lean manufacturing assembly line will be completely paperless, with computer terminals at each station of the assembly line displaying the most current product information, dimensions, test parameters, and history for each assembly. Even development prototypes for lean manufacturing systems do not use two-dimensional (2-D) paper drawings, but three-dimensional (3-D) electronic images that allow the fit of one part to another to be simulated without the fabrication of physical parts (a potential waste of materials) until their interactions and interfaces (with humans as well as other parts), interferences, and fit tolerances are known. How many sets of drawings are needed? The lean answer is “none.”

When applied to electronics manufacturing, these principles remain essentially the same as for mechanical systems. Interchangeable electronic parts, by the thousands, conveyorized assembly line production, JIT (Just In Time), TPS (Toyota Production System), TQM (Total Quality Management), and Supply Chain Management, are all critical lean manufacturing tools used in the EMPF and other modern electronics manufacturing plants. Superimposed on these tools are the basic tenets of Design for Manufacturing, Design for Assembly, and Design for Test, which augment the general principles of Lean Manufacturing and have become extremely sophisticated disciplines in the electronics manufacturing field. Manufacturing process development at the EMPF is centered on these lean manufacturing principles. The result has been the continued central role of the EMPF in Navy ManTech development.