- THE MAGAZINE
- WEB EXCLUSIVES
The United Stated has been losing its manufacturing edge for a number of years to global competitors.
Research shows that we continue to use the 1950s product control principle, PDCA (plan-do-check-act), to manage processes. Yield expectations have been inching higher every decade during the past century to almost virtual perfection now. PDCA was used initially to work with sampling plans, inspections, statistical analysis, and accept or reject criterion. The sampling inspection and accept/reject criteria led to the culture of building acceptable product, thus lost the intent for excellence.
Applying PDCA to manage process excellence is limited because of two shortcomings-plan and check. Plan was designed to plan a starting number of units to ensure the customer gets enough quantities through production, while the check was meant to verify sample outputs for acceptability using the sample selection criteria at the end of production for salvaging maximum economic benefits.
In order to achieve excellence, a new building block of process management must be created. Based on the work of Ishikawa, Juran, Taguchi, Deming and Shewhart, a process management model has been developed called the 4P model of process management. Accordingly, the 4Ps are prepare, perform, perfect and progress. Prepare is built on feed forwarding Ishikawa’s 4Ms (materials, machines, methods and manpower) to ensure no root cause of problem is ignored while setting up a process. Only a target set up can produce excellence in manufacturing.
However, setting up a perfect process needs process targets. In manufacturing, perfection means producing a well-designed product right on its target parameters. This is the most fundamental aspect of manufacture excellence. Without a clearly defined target, one cannot achieve excellence in manufacturing. Most manufacturing operations reproduce to defined upper and lower specification limits. If a process is set up close to either of the two specification limits, the production output is bound to be marginal at best, but 60% to 70% acceptable.
One of the challenges in manufacturing to the specification limits is that the process can be only managed in the accept and reject fashion, and becomes dependent on inspection and sorting activities, adding to the cost of manufacturing. Increasing inspection, sorting and testing does not represent manufacturing excellence; instead, absence of inspection, sorting and testing of manufactured product that is on target represents manufacturing excellence.
For too long we have been blaming manufacturing for flawed or imperfect design, and promoting unhealthy wasteful verification and reworking processes. Imagine a stamping part takes a fraction of a second to make and minutes to inspect. There are many shops performing 100% inspection in their desire to ship 100% acceptable product. Businesses should measure cost of measurements, testing, verification and sorting as a percentage of profit. The picture would become clear very quickly.
It is not going to be an easy task to accept the fact that building to specification limits is no good as it has been in practice for more than 50 years. Building to specification limits may produce acceptable product for some, but the cost of producing acceptable product will be higher than product produced to the well-defined targets.
People tend to produce what is asked of them. If we are asked to produce within limits, we get the product all over the specification range. If we ask our employees to produce right on target, they will find a way to produce on target. That is manufacturing excellence. In a globally competitive environment, there is no room for acceptable manufacturing capability when someone can produce excellence in manufacturing at a lower cost.
Excellence in manufacturing costs less than acceptable manufacturing because there is no added cost for inspection, testing and sorting. However, it can only begin with the leadership demanding manufacturing excellence through defined design targets. A 100% increase in the cost of design would be peanuts in manufacturing.