lean manufacturing

Genchi Genbutsu
The Toyota practice of thoroughly understanding a condition by confirming information or data through personal observation at the source of the condition. For example, a decision maker investigating a problem will go to the shop floor to observe the process being investigated and interact with workers to confirm data and understand the situation, rather than relying solely on computer data or information from others. The practice applies to executives as well as managers. In Japanese, genchi genbutsu essentially means “go and see” but translates directly as “actual place and actual thing.”
See: Gemba.

The Gemba
The Japanese term for “actual place,” often used for the shop floor or any place where value-creating work actually occurs; also spelled genba. The term often is used to stress that real improvement requires a shop-floor focus based on direct observation of current conditions where work is done. For example, standardized work for a machine operator cannot be written at a desk in the engineering office, but must be defined and revised on the gemba .

A Fulfillment Stream
A supply chain that embodies the principles of lean and therefore flows collaboratively and smoothly like a stream rather than operating as a group of connected links. The lean fulfillment stream relentlessly focuses on lead-time reduction by eliminating all nonvalue-creating activities (waste) among suppliers and producers that collaboratively create a product. This is accomplished through rigorous process discipline, inventory reduction, and first-time quality. The lean fulfillment stream flows to the demand of the customer; all supply stream activities are triggered by pull. The goal of the lean fulfillment stream is to deliver the highest value to the customer at the lowest total cost to stakeholders. (Adapted from Martichenko and Von Grabe 2008.)

The Four Ms
The variables that a production system manipulates to produce value for customers. The first three are resources; the fourth is the way the resources are used. In a lean system, the Four Ms mean:
1. Material—no defects or shortages.
2. Machine—no breakdowns, defects, or unplanned stoppages.
3. Man—good work habits, necessary skills, punctuality, and no unscheduled absenteeism.
4. Method—standardized processes, maintenance, and management.

Five Whys
The practice of asking why repeatedly whenever a problem is encountered in order to get beyond the obvious symptoms to discover the root cause. For instance, Taiichi Ohno gives this example about a machine that stopped working (Ohno 1988, p. 17):
1. Why did the machine stop? There was an overload and the fuse blew.
2. Why was there an overload? The bearing was not sufficiently lubricated.
3. Why was it not lubricated? The lubrication pump was not pumping sufficiently.
4. Why was it not pumping sufficiently? The shaft of the pump was worn and rattling.
5. Why was the shaft worn out? There was no strainer attached and metal scraps got in. Without repeatedly asking why, managers would simply replace the fuse or pump and the failure would recur. The specific number five is not the point. Rather it is to keep asking until the root cause is reached and eliminated.
See: Kaizen; Plan, Do, Check, Act (PDCA).

Five Ss
Five related terms, beginning with an S sound, describing workplace practices conducive to visual control and lean production. The five terms in Japanese are:
1. Seiri: Separate needed from unneeded items—tools, parts, materials, paperwork—and discard the unneeded.
2. Seiton: Neatly arrange what is left—a place for everything and everything in its place.
3. Seiso: Clean and wash.
4. Seiketsu: Cleanliness resulting from regular performance of the first three Ss.
5. Shitsuke: Discipline, to perform the first four Ss. The Five Ss often are translated into English as Sort, Straighten, Shine, Standardize, and Sustain. Some lean practitioners add a sixth S for Safety: Establish and practice safety procedures in the workshop and office. However, Toyota traditionally refers to just Four Ss:
1. Sifting (Seiri): Go through everything in the work area, separating and eliminating what isn’t needed.
2. Sorting (Seiton): Arrange items that are needed in a neat and easy-to-use manner.
3. Sweeping Clean (Seiso): Clean up the work area, equipment, and tools.
4. Spic and Span (Seiketsu): The overall cleanliness and order that result from disciplined practice of the first three Ss. The last S—shitsuke (sustain)—is dropped because it becomes redundant under Toyota’s system of daily, weekly, and monthly audits to check standardized work. Whether four, five, or six Ss are used, the key point to remember is that the effort is systematic and organic to lean production, not a “bolt-on” stand-alone program.
See: Standardized Work.

Every Product Every Interval (EPEx)
The frequency with which different part numbers are produced in a production process or system. If a machine is changed over in a sequence so that every part number assigned to it is produced every three days, then EPEx is three days. In general, it is good for EPEx to be as small as possible in order to produce small lots of each part number and minimize inventories in the system. However, a machine’s EPEx will depend on changeover times and the number of part numbers assigned to the machine. A machine with long changeovers (and large minimum batch sizes) running many part numbers will inevitably have a large EPEx unless changeover times or the number of part numbers can be reduced.
See: Heijunka

Error Proofing are methods that help operators avoid mistakes in their work caused by choosing the wrong part, leaving out a part, installing a part backwards, etc. Also called mistake-proofing, poka-yoke (errorproofing) and baka-yoke (fool-proofing). Common examples of error-proofing include:
• Product designs with physical shapes that make it impossible to install parts in any but the correct orientation.
• Photocells above parts containers to prevent a product from moving to the next stage if the operator’s hands have not broken the light to obtain necessary parts.
• A more complex parts monitoring system, again using photocells, but with additional logic to make sure the right combination of parts was selected for the specific product being assembled.
See: Inspection, Jidoka.

Toyota also commonly distinguishes between total efficiency, involving the performance of an entire production process or value stream, and local efficiency, involving the performance of one point or step within a production process or value stream. It emphasizes achieving efficiency in the former over the latter.
See: Overproduction, Seven Wastes

Meeting exact customer requirements with the minimum amount of resources. Apparent Efficiency vs. True Efficiency Taiichi Ohno illustrated the common confusion between apparent efficiency and true efficiency with an example of 10 people producing 100 units daily. If improvements to the process boost output to 120 units daily, there is an apparent 20 percent gain in efficiency. But this is true only if demand also increases by 20 percent. If demand remains stable at 100 the only way to increase the efficiency of the process is to figure out how to produce the same number of units with less effort and capital. (Ohno 1988, p. 61.)