As 5 why is something fairly new, or unused by me and my small company, i have asked around about its use.
I have been told that its acceptable to not necessarily use all 5 steps to get to the root cause. It maybe that 3 or 4 will do it.
Any suggestions please?
Typically you will keep asking Why until the answer leaves your span of control. For example, if your problem was you were late for work because you overslept, because your alarm did not go off because you lost power because a substation exploded because it was hit by lightning because there was an electrical storm. At some point along those Whys, you lose the ability to make a corrective action. That is when you stop. You cannot take action on anything from substation backward, but you can purchase an alarm with battery backup (or use a smartphone).As 5 why is something fairly new, or unused by me and my small company, i have asked around about its use.
I have been told that its acceptable to not necessarily use all 5 steps to get to the root cause. It maybe that 3 or 4 will do it.
Any suggestions please?
Right out of Statistical Engineering: An Algorithm for Reducing Variation in Manufacturing Processes. An excellent book.One thing that seems to be missing (besides a true commitment to improving quality) is that there is more than 1 type of action we can take (and even the standard is guilty of this).
feedback control (e.g. SPC) where the output can be seen to be changing and we know what factors to change to bring the output back into control. Think about tool wear...
feed forward control: measure a factor that can’t be easily controlled and adjust another factor to compensate for the first one.
Inspection/screening: can be a bit expensive but if a supplier is still sending you ‘off the shelf’ or ‘catalog’ material that will cause failures yet is within the material specifications you can inspect and screen out the material that doesn’t work In our application.
robust against the cause: there are some causes that cannot be controlled but we can alter the product or process against that variation. Thing ‘rust proofing’...we can’t control the rain cut we can control the material that will rust. Error proofing falls into this category. People - all people - will commit errors. We cannot stop that no matter how hard we train , yell or discipline. But we can error proof our processes.
reduce the variation in the causal factor: this is waht most people think of in correction actions
redesign the process or product to truly remove the causal factor. Usually a last resort as it can be time consuming and expensive but it may be necessary in some cases.