How to use OEE for better production: five practical ways for machine shops
An OEE number on a screen improves nothing by itself. It becomes useful when you act on it every day and every week. Five ways a CNC shop uses OEE to get more out of the same machines.
Updated: 11 October 2026
How to calculate OEE is explained in How to calculate OEE in machining. This guide is about what comes next. OEE is the product of availability, performance and quality.[1] Those three parts are what make the number useful: they show which kind of loss is the largest, and so where to start.
1. Discuss the biggest loss every morning
A five-minute standup at the shop floor screen or on a tablet works better than a monthly report. Look at yesterday's OEE per machine and pick the machine with the largest drop. Then check which part caused it: availability (setup, workpiece change, downtime), performance (a longer active time per part, short stops) or quality (scrap). Ask one question and agree on one action.
Ask what happened, not who did it. “Machine 3 stood still from 14:00 to 15:30 yesterday. What happened?” is a question everyone can work with. The goal is a smaller loss tomorrow.
2. Shorten setups and workpiece changes
Nakajima counts setup and adjustment among the big losses of a machine.[2] In machining with small batches, that loss comes back with every new batch. Measure setup time per batch and per NC program, and compare the same work across batches and operators. If one operator sets up in 20 minutes and another needs 45 for the same part, there is a method worth writing down and sharing.
Shorten setups with SMED: do everything you can while the machine is still running, such as presetting tools, laying out fixtures and reviewing the drawing.[3] For series work, also look at workpiece change time, the time to swap the workpiece between two parts. A few seconds per change sound small, but over hundreds of parts a day they add up. Setup and workpiece change are both availability losses: the machine is not machining.
3. Focus on the bottleneck machines
Not every machine matters equally. The machine where work piles up decides how much the whole shop can deliver. That is the core of Eliyahu Goldratt's Theory of Constraints.[4] An extra hour on the bottleneck is an extra hour of output for the whole company. An extra hour on a machine that is waiting for work anyway gains nothing.
So do not try to raise the OEE of every machine at once. Find the machine with the longest queue, cut its downtime and setup time first, and let it run through breaks or unattended where you can.
4. Track a trend, not a target
85% is often quoted as world class. For machining with small batches that is not a fair yardstick, because every new batch costs setup time. Compare each machine with itself instead, under the same definition, week after week. One bad day is an incident. Three bad days in a row, or a line that drops for four weeks, is a pattern.
Write down how you calculate: which time counts as planned time and how you treat unattended hours. Change the definition and your trend breaks, because you are no longer comparing the same thing.
5. Link every loss to an action
A loss without an owner stays. Keep a short action list: which loss, which measure, who does it and when you check the effect. After a few weeks, check in the data whether the loss got smaller. If not, the cause was somewhere else.
| Loss | Example action |
|---|---|
| Downtime before the first cycle | Prepare material, tools and NC program the day before. |
| Long setup | Preset tools and lay out fixtures while the machine is still running. |
| Slow workpiece change | Speed up the change program or the clamping. |
| Active time per part crept up | Check tools, feeds and the NC program. |
| Scrap during setup | Measure the first part earlier and complete the setup sheet. |
Using OEE with automatic data
For daily use the data has to be there in the morning without anyone collecting it. Smart Factory reads active time, setup time, workpiece change time, downtime and part counts straight from the CNC control and shows the OEE of every machine in the app. The color shows at a glance which machine needs attention. How to build this rhythm in your shop is covered in How do I become a Smart Factory?
Frequently asked questions
Where do I start if I want to raise OEE?
With the part that is lowest. If that is availability, look first at downtime before the first cycle, at long setups and, in series work, at workpiece change time. Those can often be reduced without any investment.
Should I improve the OEE of every machine?
No. The bottleneck machine decides how much the shop delivers. Improve there first and you will see it in lead times and revenue.
How often should we discuss OEE?
Every morning briefly, on yesterday's biggest loss, and every week on the trend per machine. Single days vary with the mix of Production Orders.
Is an OEE of 85% the goal?
Not necessarily. For small batches with frequent setups, 85% is not a fair yardstick. Compare each machine with its own trend under the same definition.
About Smart Factory
Smart Factory reads active time, setup time, workpiece change time, downtime and part counts straight from the CNC control and shows the OEE of every machine in color. More: Smart Factory and Pricing.
Sources
- ISO 22400-2:2014, Key performance indicators (KPIs) for manufacturing operations management, Part 2
- Seiichi Nakajima: Introduction to TPM. Total Productive Maintenance. Productivity Press, 1988
- Shigeo Shingo: A Revolution in Manufacturing. The SMED System. Productivity Press, 1985
- Eliyahu M. Goldratt, Jeff Cox: The Goal. A Process of Ongoing Improvement. North River Press, 1984
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