SPC implementation steps:

1) Identify key characteristics (e.g., thickness, width, bend angle, weld width). 2) Select control charts: use Xbar-R for variable data and P/NP charts for attribute data. 3) Set sampling frequency and sample size; for continuous production, sampling 5 pieces per batch is recommended. 4) Calculate control limits and distinguish between common-cause and special-cause variation. 5) A process capability of Cpk ≥ 1.33 is a commonly used requirement.

Steel processing is heavily affected by incoming material variation. It is recommended to monitor incoming material parameters at the same time to avoid mistaking incoming material problems for process problems.