I often encounter the question of why various quality management system standards require the deployment of lower level process measures if the requirement from the customer is simply to deliver conforming product on time for the contracted price?
When discussing this in the office one of my seasoned colleagues Bob Parsons, came out with the following metaphor that he heard during his travels and I thought it might be nice to share with you all.
Imagine that you were to get into a car that only had one gauge on the instrument panel, a speedometer, and were to start driving down the interstate with a goal of maintaining a speed of 55mph, the chances are you would focus upon the speedometer and adjust the amount of pressure you applied to the accelerator to maintain a steady 55, and I hazard a guess that you would be reasonably successful in meeting this goal. Now after a period of time all things being equal the car would probably start to slow down and eventually come to a stop. Since the car only has the one gauge it would be difficult to ascertain the exact reason why the vehicle was slowing down. Most of us would make an educated guess that the vehicle had simply ran out of gas and indeed this may be the case, but this would be an assumption, not a conclusion based upon data.
Of course, the vehicle may have overheated, run out of oil or got a flat battery, with only one gauge it would be difficult to ascertain which system has failed or to get an early warning and hence react to the fact that a system was close to failing such as the fuel was running low or the vehicle was starting to overheat. Hence why modern cars have an array of gauges and lights to give the driver an instant status report of the current health of the vehicle and what actions, such as a need to get more gas, change the oil, fit new brakes, need to be performed prior to the vehicle suffering a catastrophic failure.
And such is the case for lower level process measurements. Although the goal is to produce conforming material and deliver the product on time, discovering there was a system issue at the point of delivery or post delivery is not an effective way of pro actively managing customer requirements. Like a modern vehicle, a process has a number of different components that need to be monitored to ensure they are operating within specified process parameters. If the process to ensure that the vehicle has sufficient gas does not work the car may breakdown, similarly if the process to ensure that the barrel temperatures on an injection molding machine are within tolerance is not effective or does not exist, then if the temperature does move out of tolerance the potential to produce and possibly ship non conforming material is that much greater. An early warning such as a fuel warning light or an alarm on the barrel temperature indicating that a process parameter is of concern, prior to a process failure occurring gives the driver or operator an opportunity to react and ensure that action is taken to bring the process back under control. When these reactions occur it ensures that the goal of keeping the vehicle moving or producing conforming product will be achieved. Finding out that a barrel temperature was out of specification after non conforming product has been shipped or is ready to ship can negatively impact the primary objectives of delivering conforming product on time. Ensuring critical lower level processes have been identified, are being monitored and have parameters established can ensure that the top level goal of achieving customer requirements can consistently be achieved.
So take a moment, critically evaluate your processes and establish where the failure points may occur and ensure that tracking mechanisms are in place, no one likes to see the check engine light appear, but it sure beats the hell out of breaking down at 2am in the morning on a cold wet night on the I-90 with no cell reception somewhere in South Dakota.