---
title: "How Can a Manufacturing Process Have a High Cp but a Low Cpk?"  
description: "How Can a Manufacturing Process Have a High Cp but a Low Cpk?"  
author: "Lasse Dahl"  
published: 2026-10-18  
canonical: https://answers.mindstick.com/qa/117863/how-can-a-manufacturing-process-have-a-high-cp-but-a-low-cpk  
category: "Mix Category"  
tags: ["manufacturing", "quality control", "Statistical Process Control"]  
reading_time: 1 minute  

---

# How Can a Manufacturing Process Have a High Cp but a Low Cpk?

In a quality-control exercise for a machined shaft, the process capability report shows **Cp = 1.67** but **Cpk = 0.72**. I initially read the Cp value as evidence that the process could comfortably meet the drawing tolerance, so the much lower Cpk has thrown me.

## What should I investigate first?

- Does this gap suggest that the process average is too close to one specification limit, rather than that the spread is too wide?
- Would adjusting the machine offset be enough, or would that conclusion require more evidence?
- How should I interpret either index if the control chart shows drift during the sampling period?

I am looking for a practical explanation of **Cp and Cpk in manufacturing**: what each number tells an operator, and what it cannot establish on its own. The exercise assumes a roughly normal distribution, but it does not say whether process stability was checked first.


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Original Source: https://answers.mindstick.com/qa/117863/how-can-a-manufacturing-process-have-a-high-cp-but-a-low-cpk

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