First Pass Yield Calculation

First Pass Yield (FPY) Calculator

function calculateFPY() { var total = parseFloat(document.getElementById('totalUnits').value); var scrapped = parseFloat(document.getElementById('scrappedUnits').value) || 0; var reworked = parseFloat(document.getElementById('reworkedUnits').value) || 0; var resultDiv = document.getElementById('fpyResult'); var percentageDiv = document.getElementById('fpyPercentage'); var detailsDiv = document.getElementById('fpyDetails'); if (isNaN(total) || total total) { alert('The sum of scrapped and reworked units cannot exceed the total units started.'); return; } var goodUnits = total – sumLost; var yieldRate = (goodUnits / total) * 100; resultDiv.style.display = 'block'; resultDiv.style.backgroundColor = '#f0fff4'; resultDiv.style.border = '1px solid #c6f6d5'; percentageDiv.innerHTML = yieldRate.toFixed(2) + '%'; percentageDiv.style.color = yieldRate > 90 ? '#27ae60' : (yieldRate > 70 ? '#f39c12' : '#e74c3c'); detailsDiv.innerHTML = 'Out of ' + total + ' units, ' + goodUnits + ' passed the process without any rework or scrap.'; }

Understanding First Pass Yield (FPY)

First Pass Yield (FPY), also known as Quality Productivity Ratio (QPR), is a critical Key Performance Indicator (KPI) in manufacturing and service industries. It measures the efficiency of a production process by determining the percentage of units that complete a process correctly the first time without needing rework, repair, or being scrapped.

The FPY Formula

The mathematical representation for calculating First Pass Yield is:

FPY = (Units Entering Process – Scrapped Units – Reworked Units) / Units Entering Process

Why FPY Matters in Lean Six Sigma

Unlike standard yield metrics, which might only look at the final output regardless of how much rework was required, FPY exposes the "hidden factory." The hidden factory refers to the wasted time, labor, and materials used to fix mistakes. A high FPY indicates:

• Lower operational costs (less wasted material).
• Higher labor efficiency (no time spent on rework).
• Better product quality and consistency.
• Faster throughput times.

Example Calculation

Imagine a production line where you start with 500 electronic components. During the quality check:

• 15 components are found defective and are thrown away (Scrapped).
• 25 components have minor soldering issues and are sent back for repair (Reworked).

Step 1: Identify successful units = 500 – 15 – 25 = 460 units.
Step 2: Calculate Yield = (460 / 500) = 0.92.
Step 3: Convert to percentage = 92%.

In this scenario, while you might eventually finish 485 units (including the 25 reworked ones), your First Pass Yield is 92%. The 8% gap represents the opportunity for process improvement.

FPY vs. Rolled Throughput Yield (RTY)

While FPY measures a single step, Rolled Throughput Yield (RTY) measures the probability that a unit will pass through an entire series of steps without defects. RTY is calculated by multiplying the FPY of every individual step in the process. If you have five steps each with a 90% FPY, your RTY would be 0.9 x 0.9 x 0.9 x 0.9 x 0.9 = 59%.