For a product, noise factors would include customers usage conditions, environment and aging. Manufacturing variability is also noise. For example, you can t ask your computer not to use a certain brake when temperature is less than 20 degrees Fahrenheit. There are also many noises for manufacturing processes. For example, incoming material variability, lot to lot, within batch variability, operator, and shift to shift, to name a few.
Noise factors cause variability in the function of products and processes.
Noise also causes problems and failures, and that s what starts fires. And we spend a lot of time fighting fires. It is said that 75 percent of an engineer s time at any given company is spent on fire fighting. We must reduce this number. There are three types of countermeasure we can apply to noises.