The Northern Echo and BKR Haines Watts have teamed up to give world-class manufacturing advice to companies in the Tees Valley. This week Paul Bell, of BKR Haines Watts, looks at the concept SPC.

SPC, Statistical Process Control, is a means of preventing defects by monitoring trends in the output from a process.

Traditionally, this has involved drawing a run chart of the measured output from a process, with an upper and a lower control limit marked on the chart. The positioning of the control limits is determined statistically.

Samples are taken at regular intervals from the process, are measured and are marked on the control chart. When a trend is evident, or where output falls outside the control zone, the root cause can then be investigated and procedures put in place to minimise future deviations.

Detailed evaluation of data over time can reveal the influence of external factors such as run speed, operator input, material composition, equipment adjustment, start-up and shutdown, maintenance regime, etc.

A more user-friendly approach is to use Pre-Control Charts, which are colour coded (green is OK, yellow warns that the process is slipping out of control, red means stop) and are based on customer quality standards.

TOP TIP: Newcastle University's Industrial Statistics Research Unit (0191-222 8513) is an internationally-recognised authority on SPC, and can support companies in improving their processes.

l Paul Bell is the manufacturing and business improvement manager for BKR Haines Watts, working with local companies to improve their performance and profitability. He can be contacted on (01325) 254700.