1. What is Process Capability Analysis?

Process capability analysis measures how well a process meets specification limits. Cp and Cpk are statistical measures that quantify process capability and performance relative to specification requirements.

2. How Does the Calculator Work?

The calculator uses the process capability formulas:

Where:

• \( USL \) — Upper Specification Limit
• \( LSL \) — Lower Specification Limit
• \( \sigma \) — Process Standard Deviation
• \( \mu \) — Process Mean

Explanation: Cp measures potential capability assuming the process is centered, while Cpk measures actual capability accounting for process centering.

3. Importance of Cp and Cpk

Details: These indices help manufacturers determine if their processes can consistently produce products within specification limits. Higher values indicate better process capability.

4. Using the Calculator

Tips: Enter all values in consistent units. Standard deviation must be greater than zero. The calculator provides both Cp and Cpk values.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good Cp/Cpk value?
A: Generally, Cp/Cpk ≥ 1.33 indicates capable process, ≥ 1.67 indicates excellent capability. Values < 1.0 indicate process may not meet specifications.

Q2: What's the difference between Cp and Cpk?
A: Cp measures potential capability if process is centered, while Cpk measures actual capability accounting for process mean location.

Q3: When should I use Cp vs Cpk?
A: Use Cp when process is centered, Cpk when process may not be centered. Cpk is generally more conservative.

Q4: Can Cp be greater than Cpk?
A: Yes, this indicates the process is not centered between specification limits. Cp represents potential capability if centered.

Q5: What if my process has only one specification limit?
A: For one-sided specifications, use Cpk calculation with the available limit. Cp cannot be calculated with only one limit.