QM Knowledge: Statistical Process Control

The quality of the products offered has a considerable influence on the competitiveness of a company. Errors in production are often difficult to trace in retrospect and can result in high costs due to lost working time and wasted materials. Statistical process control (SPC) provides a remedy.

SPC stands for Statistical Process Control and uses statistical methods to investigate how production processes and service processes can be optimized. For this purpose, statistical data is collected and analyzed during an ongoing production process.

On the one hand, the aim is to ensure that the process is stable within predefined tolerance limits. On the other hand, deviations can be detected and corrected at an early stage through statistical process control. As a result, a faulty product is ideally not produced in the first place. Rejects are reduced, costs are lowered and customer satisfaction is increased.

For the analysis, the process to be analyzed is first defined and described. The measured variables required for the analysis are then determined. These measured values are recorded at fixed intervals so that a successful evaluation can be carried out.

Statistical methods are used to analyze process data, identify trends and transfer them to any existing patterns. The result: a basis on which measures can be defined to optimize the production process.

Companies in a wide range of industries use statistical process control as part of their quality management:

• In the automotive industry, critical characteristics such as dimensions and material properties are defined and then monitored in the series production process. Checks are carried out to ensure that the production of individual components such as engines and body parts is of consistent quality.
• In the food industry, characteristics such as temperature or fill level are of interest during the ongoing production process, as these have a significant influence on the quality of the end product.
• In the production process of a company that manufactures electronic components, processes such as the soldering of circuit boards, the assembly of individual components or the testing of circuits play a role.

SPC software helps you to monitor and control production processes. This helps you to avoid errors and ensure the profitability of your company. Different types of software can be used for SPC, including generic calculation software (e.g. spreadsheets) or integrated CAQ solutions. Special CAQ solutions significantly reduce the workload in contrast to generic calculation software. In addition to SPC software, a CAQ solution offers additional quality management modules such as FMEA, supplier evaluation or process control plans.