How to use OEE and TEEP to calculate plant losses

Two metrics that help plant teams measure and improve the equipment performance are Overall Equipment Effectiveness (OEE) and Total Effective Equipment Performance (TEEP). While both provide valuable insights into equipment performance and capacity utilization, they differ in focus and application. 

This article is a companion to What Is OEE and TEEP? which explains each of these metrics in detail, including the following formulas for calculating them:

OEE = Availability × Performance × Quality
TEEP = OEE × Loading

Where:

• Availability = Scheduled Time minus breakdowns, process failures and setup & adjustment downtime / Scheduled Time
• Performance = Actual Output / Theoretical Output at Designed Speed
• Quality = Good Units Produced / Total Units Produced
• Loading = Scheduled Time / Total Calendar Time

This article explains how to calculate the variables that comprise each of the above equations.  Understanding these metrics is essential for identifying improvement opportunities and maximizing the potential of manufacturing assets. 

Remember to calculate each variable based on your chosen time period of focus (i.e., weekly, monthly, annually, etc.); the examples in this article will focus on a period of one week.

Step 1: Scheduled Time

Figure all scheduled downtime by putting time scheduled in each of these buckets: Changeovers, Engineering Planned Shutdown, Maintenance Planned Shutdown, Operations Planned Shutdown, or No Customer Orders.

Then add them all up to come up with total planned downtime, and subtract that from total hours in a week (168 hours available). This gives you your available time to produce and your Loading calculation.

Example: Planned Maintenance 24 hours plus Changeovers 4 hours = 28 hours of scheduled downtime. 168 hours in a week minus 28 hours planned gives you 140 hours available to produce.
Loading calculation: 140 scheduled hours/168 available hours = 83%

Step 2: Quality 

Add together your startup reject units and in process reject units, and subtract them from your total units produced.

Example: 35 startup rejects + 35 in process rejects = 70 rejects. Let’s say we produced a total of 7,070 units. 7,070-70 = 7,000 good units produced.

Quality Calculation: Good Units Produced / Total Units Produced, or 7,000/7070 = 99%

Step 3: Net Good Processing Hours

Find your net good processing hours by dividing your average weekly throughput by your design rate weekly.

Example: Average weekly rate is 7,000 units produced. Design rate is 100 units per hour. 7,000/100 = 70 net good processing hours.

Then, divide the net good processing hours by the available hours per week. 

Example: Available hours per week average is 140 hours. 70 net good processing hours/140 available hours = 50%

Step 4: Availability

Take your breakdown downtime, process failure downtime and Set/Adjustment downtime, add them together and subtract from the available time.

Example: 13 hours of breakdowns a week + 1 hour of process failures + 1 hour of setup/adjustment downtime = 15 hours of availability downtime. 140 available hours minus 15 downtime hours = 125 hours left to produce.

Availability Calculation: 125 hours after downtime/140 hours available = 89%

Step 5: Performance

This is a multi-step calculation that requires you to identify both speed losses and minor stops.

Speed Losses. To find speed losses, first calculate units per hour lost by subtracting Actual Run Rate from Design Rate:

Example: Design Rate 100 per hour, Actual Run Rate 85 per hour = 15 units per hour lost.

Then, to calculate hours lost to speed losses, divide the Actual Run Rate by the Design Rate, subtract from 100, and multiply by available hours left to produce:

Example: 85/100 = 85% - 100 = 15%; 15% multiplied by 125 available hours left to produce = 19 hours lost to speed losses. 

Minor Stops. To find minor stops, first take your available hours left to produce and subtract both hours from speed losses and net good processing hours: 

Example: 125 available hours – 19 speed loss hours – 70 net good processing hours  = 106 hours left to produce = 36 hours of minor stops per week.

Performance Calculation: 
19 hours in speed losses plus 36 hours of minor stops = 55 hours of perf. losses
125 available hours minus 55 hours of perf. losses = 70 net hours
70 net hours / 125 available hours = 56%

Example OEE/TEEP Calculations and Big Loss Totals

OEE = Availability × Performance × Quality
OEE = 89% × 56% × 99% = 49%

TEEP = Loading Time × OEE
TEEP = 83% × 49% = 41%

7 Big Losses:

•    Minor Stops: 36 hours per week

•    Speed Losses: 19 hours per week

•    Breakdowns: 13 hours per week

•    Setup/Adjustment Losses: 1 hour per week

•    Process Failures: 1 hour per week

•    Quality Startup Losses: 0.5 hours per week

•    Quality In-Process Losses: 0.5 hours per week

These results now shows where to focus. Where would you focus? Where can you help as a maintenance department?