Manufacturers who experience high process variation and overfill can save money by using Statistical Process Control (SPC) to understand the true sources of variation and make permanent corrective actions in their operations. 

By using an Xbar/R Control Chart, a method of Statistical Process Control (SPC), manufacturers can reduce fill weight variation, maintain centerlines and avoid rework.

However, control charts should be implemented carefully. Here are best practices to keep in mind:

  • Quality operators should start by identifying the connection between process inputs and the outputs so they can fully understand the effects of process adjustment. This helps them to respond appropriately to out-of-control processes, and to quickly center those processes. It also enables them to qualify the estimated control limits.
  • Operators should also use control chart test rules to ensure they can maintain in-control processes.
  • Leaders should first educate quality operators on the benefits and use of control charts and should mentor operators at the process lines during charting. 
  • Operators are encouraged to develop daily chart reviews to ensure that charts are utilized correctly, chart center lines are achieved, and to minimize maximum allowable variance violations.
  • Operators should also regularly review variation activity. Has it lessened and will control limits need to be recalculated?
  • A consistent capability analysis will also help to establish new centerlines.   

Although applying methods of capability analysis and statistical process control significantly helps to reduce overfill, it is not the entire answer. Manufacturers should consider implementing these charts with the addition of lean tools, techniques and methods. This will help to boost continuous flow of materials, increase equipment uptime and reduce changeover time. The collective effort can lead to savings and better throughput.