six sigma or 6s, is Quality control philosophy in which you are trying to reduce process variance to levels higher than 6 sigma. Sigma, in the statistical world is a way to measure standard deviation from a mean, six sigma would be no more than 1 defect per 1.37 million parts, if my memory serves me correct. something like .00013% rejected parts.
It's very big in japan and other high volume manufacturers such as automotive suppliers and hardware manufacturers, in which process variation is a bad thing. All engineering managers always talk about lean-manufacturing and six sigma.
In reference to welding it's generally only used in robotic applications or on consumable materials such as filler. Generally not used in too many manual fabrication projects such as welding because most welding outfits don't have a "tight" enough system to generate accurate or useful statistical data. OR don't make the effort.
http://en.wikipedia.org/wiki/Six_SigmaI've used it, but it's not my favourite quality control philosophy.
Forum
