Xentara - the fast track to OEE Monitoring

The Big Idea

Often referred to as the gold standard for productivity development, OEE (Overall Equipment Effectiveness) is a method of gauging manufacturing output. Most simply, it is a percentage indicating how much of the time spent on production really produces good items. Thus, a factory with an OEE score of 100% operates without interruptions, at maximum speed, and does not manufacture defective goods.

100% Availability (no downtime or disruptions)

All processes operating at the maximum feasible speed constitute 100% performance.

• 100% Quality (no faulty components made)

Understanding your OEE score and the values of its components (Availability, Performance, and Quality) helps one to act more readily against the fundamental reasons of lost production.

Monitoring your production data using Xentara will let you to quickly establish OEE calculations and view your OEE score in real-time.

Major Losses

In a perfect world, as machines and people churn along according to schedule, OEE would always be at 100%. Unfortunately, in practice this is never the case. Maintenance, retooling, replenishing consumables, etc. inevitably create downtimes. Then there are little problems like small halts or slowdowns. Often a pipe dream is 100% quality, last but not least. Material still being fed into the machine causes the first unit in a lot to virtually always have defects, and there is always the chance of error.

All these elements—and several possible others—indicate a decline in efficiency, hence we call them Major Losses. The table below shows some potential illustrations:

Data Collection

Based on several complicated factors, OEE is a somewhat straightforward computation. While counting good and bad products is rather trivial, correctly determining the performance of a production process is a lot more complicated, necessitating a lot of data from many different sources.

The Old Days...

Yes, in the “good old days”, all information on production, machine status, consumption etc. had to be collected by hand. On paper. And remember, after all that tedious data collection, some poor chap still had to manually do the calculations…

Today: Xentara Enabled

Xentara now lets you gather data from the whole shop floor automatically and in genuine real-time.

Xentara can connect to everything in your factory—from a single sensor to an array of PLCs—using its unmatched open I/O interface and flexible Skill system. Whether you're digitalising a Brownfield environment or constructing from the bottom up, Xentara lets you effortlessly gather and compile data from legacy field buses or IoT protocols, straight from compatible sensor gear or all types of additional sources. Industry 4.0 has been waiting for the "missing link" on the shop floor and the ideal connection between OT and IT.

The Xentara system is always expanding. Supported are most significant industrial buses; new connection skills are always being created at an always rising pace. Among the criteria included with Xentara are these few.

Xentara's semantic data model manages and compiles the gathered information. Here it can be processed and filtered directly inside Xentara before e.g. streaming to InfluxDB, where your gathered data is automatically analysed by AI and Machine Learning entities. Results are available right away so you may see any "live" changes as they occur. You always have all status information and production parameters right at your fingertips.

All the complex computations originally performed weekly from piles of paper forms now run in the background and update themselves constantly. C ontinually current, OEE is now a live impression available at any moment rather than a weekly or monthly report. Tools like Grafana also let you to design unique dashboards for whatever particular values or computations you choose to view.

Unlike any cloud based IoT platform, Xentara can even feed back the insights from your analysis directly into the currently running processes because of its real-time nature and perfect timing control, producing a production that continuously optimises itself—but that goes beyond the subject of OEE.

Appendix: FOR THE NUMBER CRUNCHER

OEE is calculated by multiplying the three OEE factors: Availability, Performance, and Quality.

Availability

Availability considers all occurrences halting intended production long enough to warrant tracking a cause for being down (usually several minutes).

Availability is the Run Time to Planned Production Time ratio:

Availability = Run Time / Planned Production Time

Run Time is simply Planned Production Time less Stop Time, where Stop Time is defined as any time the manufacturing process was meant to be running but was not due to unforeseen stops (e.g., breakdowns) or planned stops (e.g., changeovers).

Run Time = Planned Production Time − Stop Time

Performance

Performance considers anything that, when the manufacturing process is underway, causes it to operate at less than the maximum feasible speed; this includes both slow cycles and minor stops.

Performance is the ratio of Net Run Time to Run Time. It is calculated as:

Performance = (Ideal Cycle Time × Total Count) / Run Time

In best conditions, Ideal Cycle Time is the quickest cycle time your process can reach. So, when it is multiplied by Total Count the outcome is Net Run Time (the quickest feasible time to produce the components).

Since rate is the reciprocal of time, Performance can also be calculated as:

Performance = (Total Count / Run Time) / Ideal Run Rate

Performance should never be greater than 100%. If it is, that usually indicates that Ideal Cycle Time is set incorrectly (it is too high).

Quality

Quality considers produced components failing quality criteria, especially those requiring rework. Keep in mind that OEE Quality, like First Pass Yield, defines good parts as those that successfully pass through the manufacturing process the first time without requiring any rework.

Quality is calculated as:

Quality = Good Count / Total Count

This is the same as calculating the ratio of Fully Productive Time (only good components produced as quickly as feasible with no stop time) to Net Run Time (all parts produced as fast as possible with no stop time).

OEE Formula

OEE takes into account all losses, resulting in a measure of truly productive manufacturing time. It is calculated as:

OEE = Availability × Performance × Quality

If the equations for Availability, Performance, and Quality are substituted in the above and reduced to their simplest terms, the result is:

OEE = (Good Count × Ideal Cycle Time) / Planned Production Time

This is the "simplest" OEE computation mentioned above. Multiplying Good Count by Ideal Cycle Time produces Fully Productive Time—manufacturing only Good Parts, as fast as feasible, with no Stop Time—as mentioned above.

Why the Preferred OEE Calculation?

OEE scores offer a really useful insight—a precise image of how well your manufacturing process is going. Tracking changes in that process over time becomes simple as well.

Your OEE score does not offer any insights on the underlying reasons of lost production. Availability, Performance, and Quality serve in this capacity.

The recommended calculation gives you the best of both worlds. Three figures that reflect the basic character of your losses—Availability, Performance, and Quality—and one number that reflects how well you are doing (OEE).

Here is an interesting example. Look at the following OEE data for two sequential weeks.

OEE is improving. Great job! Or is it?

Dig a little deeper and the image is less clear. Most businesses would not want to raise Availability by 5.0% at the cost of lowering Quality by 4.5%.

Always considering the three fundamental values your OEE is founded on helps to explain this. It is nevertheless a good long-term sign of the effectiveness of your production.