A statistical tool used to measure a manufacturing process's ability to produce output within specified limits.
The Process Capability Index (CPK) quantifies the capability of a production process by comparing its natural variation to the permissible tolerance limits. It is a critical parameter for quality control in manufacturing, as it indicates how centered the process is relative to the specification limits and how much variability exists. By calculating CPK, manufacturers can assess whether their processes are capable of meeting production requirements, leading to fewer defects and improved efficiency.
In an automotive manufacturing plant, CPK is used to assess the precision of machining operations for engine components.
Typically used during the final testing phase to ensure that engine pistons are within the required diameter specifications of 88.90 mm ±0.020 mm (3.500 in ±0.0008 in). This helps maintain engine performance and reliability.
In semiconductor manufacturing, CPK helps analyze the thickness uniformity of oxide layers on silicon wafers.
Critical when fabricating integrated circuits where oxide layer thickness must be maintained at 200 nm ±10 nm. This ensures optimal transistor performance and yields.