Six Sigma SPC's
Quality Control Dictionary and Glossary
2070 W. Washington St. #5 Springfield IL
62702 Ph: 217.698.0063
6 Sigma Statistical Process Control (SPC) Software for Windows
USL, (Upper Specification Limit),
is the greatest amount in which a process or product is within the
acceptable performance limits.
This limit may be close to 3 sigma higher
than the nominal or expected mean of any process or product.
There is usually a LSL,
(Lower Specification Limit) also. A lot of products will only
have one limit. Either an upper or lower control limit. These are
sometimes called 'One Sided Specs'. A Cp
cannot be calculated for one sided specs.