1. What is a PTR to Precision Calculator?

Definition: This calculator determines the precision (P) based on the precision-to-tolerance ratio (PTR) and the tolerance (T) using the formula P = PTR × T.

Purpose: It helps engineers and quality control professionals determine appropriate precision requirements for measurements and manufacturing processes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P \) — Precision (context-specific units, typically mm)
• \( PTR \) — Precision-to-tolerance ratio (dimensionless)
• \( T \) — Tolerance (context-specific units, typically mm)

Explanation: The precision is calculated by multiplying the precision-to-tolerance ratio by the tolerance value.

3. Importance of PTR Calculation

Details: Proper precision calculation ensures measurement systems are capable of verifying product conformance to specifications and helps maintain quality standards.

4. Using the Calculator

Tips: Enter the PTR (typically between 0.1 and 0.2 for most applications) and the tolerance value. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical PTR value?
A: Common PTR values range from 0.1 to 0.2, with 0.1 being more stringent (10% of tolerance).

Q2: How does PTR relate to measurement system analysis?
A: PTR is used in GR&R (Gage Repeatability and Reproducibility) studies to evaluate measurement system capability.

Q3: When would I need to calculate precision?
A: When setting up quality control procedures, selecting measurement equipment, or validating measurement systems.

Q4: Can I use different units?
A: Yes, as long as both P and T use the same units. The PTR is dimensionless.

Q5: What's the difference between precision and tolerance?
A: Tolerance is the allowable variation in a part dimension, while precision is the capability of your measurement system to reliably detect that variation.