I will explain the key points when using QE(Quality Engineering) in several steps. For the time being, I will write from the point I came up with.
Key points: Clarify your ideals!
Since QE has a word of "Quality", you tend to evaluate "Quality characteristics" when performing QE experiments. For example, "Quality characteristics" means that there are no scratches, no burrs, no dents, etc. This "Measurement of quality characteristics" is wrong. First, it is necessary to clarify the “Objective(purpose) function”. “Purpose” is “the way it should be” or “ideal”. If the developper or engineer blur, loses, or frequently changes the "Objective function", it will be difficult to solve the problem. As soon as the quality department says, "You should improve the quality characteristics.", you forget this "Objective function." For example, two hollow tubes are joined at each end faces and then the liquid flows into the tube. If you set the "Objective function" is "high bonding strength", you will get the wrong condition settings as result. Even if the strength is satisfactory, there may be gaps in some parts and the liquid may leak. Or the hollow part may be buried and the liquid may not flow. If you set “there is no burr” as “Objective function”, strength may be insufficient. In this case, you should set the “Objective function” is “liquid flows without leakage”.
The output obtained by inputting instructions and intentions into a certain system is the "Objective function" itself ,or "Generic function" that can be evaluated .
Please see the document → QE3
For example, if the input power is used 100% for the rotation of the motor, it should be reflected in the output, but in reality energy is wasted on vibration and noise. If you can set the functionality so that the energy efficiency is 100% of the ideal, the quality characteristics ( vaibration or noise)will be improved at the same time.I think that developper or engineers should always be aware of clarifying this "Objective function (ideal)", regardless of whether you use QE or not. If you blur “Objective function”, you won't understand what you are developing. After today, you should remember that “clarify the Objective function (ideal)”.