Oee Calculation Example

OEE (Overall Equipment Effectiveness) Calculator

OEE Calculation Results

Availability: —

Performance: —

Quality: —

Overall Equipment Effectiveness (OEE): —

function calculateOEE() { var plannedProductionTime = parseFloat(document.getElementById('plannedProductionTime').value); var runTime = parseFloat(document.getElementById('runTime').value); var goodUnits = parseFloat(document.getElementById('goodUnits').value); var totalUnits = parseFloat(document.getElementById('totalUnits').value); var idealCycleTime = parseFloat(document.getElementById('idealCycleTime').value); var errorMessagesDiv = document.getElementById('errorMessages'); errorMessagesDiv.innerHTML = "; // Clear previous errors // Reset results document.getElementById('availabilityResult').innerText = '–'; document.getElementById('performanceResult').innerText = '–'; document.getElementById('qualityResult').innerText = '–'; document.getElementById('oeeResult').innerText = '–'; // Input validation if (isNaN(plannedProductionTime) || plannedProductionTime <= 0) { errorMessagesDiv.innerHTML = 'Please enter a valid Planned Production Time (must be a positive number).'; return; } if (isNaN(runTime) || runTime plannedProductionTime) { errorMessagesDiv.innerHTML = 'Actual Run Time cannot be greater than Planned Production Time.'; return; } if (isNaN(goodUnits) || goodUnits < 0) { errorMessagesDiv.innerHTML = 'Please enter a valid number for Good Units Produced (must be non-negative).'; return; } if (isNaN(totalUnits) || totalUnits totalUnits) { errorMessagesDiv.innerHTML = 'Good Units Produced cannot be greater than Total Units Produced.'; return; } if (isNaN(idealCycleTime) || idealCycleTime <= 0) { errorMessagesDiv.innerHTML = 'Please enter a valid Ideal Cycle Time per Unit (must be a positive number).'; return; } // Calculate Availability var availability = (runTime / plannedProductionTime) * 100; if (plannedProductionTime === 0) availability = 0; // Avoid division by zero if planned time is 0, though validated above // Calculate Performance var theoreticalProduction = runTime / idealCycleTime; var performance = (totalUnits / theoreticalProduction) * 100; if (runTime === 0 || idealCycleTime === 0) performance = 0; // Avoid division by zero // Calculate Quality var quality = (goodUnits / totalUnits) * 100; if (totalUnits === 0) quality = 0; // Avoid division by zero // Calculate OEE var oee = (availability / 100) * (performance / 100) * (quality / 100) * 100; // Display results document.getElementById('availabilityResult').innerText = availability.toFixed(2) + '%'; document.getElementById('performanceResult').innerText = performance.toFixed(2) + '%'; document.getElementById('qualityResult').innerText = quality.toFixed(2) + '%'; document.getElementById('oeeResult').innerText = oee.toFixed(2) + '%'; } // Initial calculation on page load with default values document.addEventListener('DOMContentLoaded', calculateOEE);

Understanding Overall Equipment Effectiveness (OEE)

Overall Equipment Effectiveness (OEE) is a critical metric used in manufacturing to measure how effectively a manufacturing operation is utilized. It provides a comprehensive view of how well a production process is performing by breaking down its performance into three measurable components: Availability, Performance, and Quality.

What is OEE?

OEE is a percentage that represents the proportion of manufacturing time that is truly productive. A score of 100% OEE means you are manufacturing only Good Parts, as fast as possible, without Stop Time. In reality, achieving 100% OEE is almost impossible, but it serves as an ideal benchmark for continuous improvement.

The Three Pillars of OEE

1. Availability

Availability accounts for all events that stop planned production for a significant period (e.g., equipment breakdowns, material shortages, setup/adjustment times). It measures the percentage of time the machine was actually running compared to the time it was planned to run.

Formula: Availability = (Actual Run Time / Planned Production Time) × 100%

  • Planned Production Time: The total time the equipment is scheduled for operation.
  • Actual Run Time: Planned Production Time minus all downtime (planned and unplanned).

2. Performance

Performance accounts for factors that cause the equipment to operate at less than its maximum possible speed (e.g., minor stops, slow cycles). It measures how fast the equipment is running compared to its ideal cycle time.

Formula: Performance = (Ideal Cycle Time × Total Units Produced) / Actual Run Time × 100%

  • Ideal Cycle Time: The theoretical minimum time to produce one unit.
  • Total Units Produced: The total number of units produced during the Actual Run Time, including rejects.

3. Quality

Quality accounts for manufactured products that do not meet quality standards (e.g., rejects, rework). It measures the percentage of good units produced out of the total units produced.

Formula: Quality = (Good Units Produced / Total Units Produced) × 100%

  • Good Units Produced: Units that meet quality specifications.
  • Total Units Produced: All units produced, including those that are defective.

Calculating OEE

Once you have calculated Availability, Performance, and Quality, you multiply them together to get the OEE score.

Formula: OEE = Availability × Performance × Quality

(Note: When multiplying, convert percentages to decimals, e.g., 90% becomes 0.90)

Example Scenario

Let's consider a manufacturing line for a single 8-hour shift (480 minutes).

  • Planned Production Time: 480 minutes
  • Downtime: 60 minutes (e.g., 30 min for setup, 30 min for breakdown)
  • Actual Run Time: 480 – 60 = 420 minutes
  • Ideal Cycle Time per Unit: 0.4 minutes (meaning 1 unit every 24 seconds)
  • Total Units Produced: 1000 units
  • Rejected Units: 50 units
  • Good Units Produced: 1000 – 50 = 950 units

Using the calculator above with these values:

  • Availability: (420 / 480) × 100% = 87.50%
  • Performance: ((0.4 × 1000) / 420) × 100% = (400 / 420) × 100% = 95.24%
  • Quality: (950 / 1000) × 100% = 95.00%
  • OEE: 0.8750 × 0.9524 × 0.9500 × 100% = 79.00%

This OEE score of 79.00% indicates that the equipment is operating at 79% of its theoretical maximum potential during the planned production time, considering all losses.

Why is OEE Important?

OEE is a powerful tool for identifying and quantifying productivity losses. By understanding the individual components, businesses can pinpoint specific areas for improvement:

  • A low Availability score suggests issues with downtime (maintenance, changeovers, breakdowns).
  • A low Performance score points to speed losses (minor stops, reduced speed).
  • A low Quality score highlights defects and rework issues.

Regularly tracking OEE helps manufacturers make data-driven decisions to optimize their processes, reduce waste, increase throughput, and ultimately improve profitability.

Leave a Reply

Your email address will not be published. Required fields are marked *