1. What is CPK and DPMO?

CPK (Process Capability Index) measures how well a process can meet specification limits, while DPMO (Defects Per Million Opportunities) quantifies the number of defects in a process per million opportunities.

2. How Does the Calculator Work?

The calculator uses the following formulas:

Where:

• \( USL \) — Upper Specification Limit
• \( LSL \) — Lower Specification Limit
• \( Mean \) — Process Mean Value
• \( \sigma \) — Standard Deviation
• \( Defects \) — Number of Defects
• \( Opportunities \) — Total Opportunities

Explanation: CPK indicates process capability with higher values indicating better performance. DPMO measures defect rate with lower values indicating better quality.

3. Importance of CPK and DPMO

Details: These metrics are crucial for quality control, process improvement, and Six Sigma initiatives. They help identify process variability and defect rates.

4. Using the Calculator

Tips: Enter all required values including specification limits, mean, standard deviation, defects count, and total opportunities. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a good CPK value?
A: Generally, CPK ≥ 1.33 indicates a capable process. CPK ≥ 2.0 is considered excellent (Six Sigma level).

Q2: How is DPMO related to Sigma level?
A: DPMO of 3.4 corresponds to Six Sigma level (3.4 defects per million opportunities).

Q3: What's the difference between CP and CPK?
A: CP measures potential capability while CPK measures actual capability considering process centering.

Q4: When should I use this calculator?
A: Use for quality control analysis, process capability studies, and Six Sigma project calculations.

Q5: Are there limitations to these metrics?
A: These metrics assume normal distribution and may not be accurate for non-normal processes or small sample sizes.