If you have not already started using OEE (Overall Equipment Effectiveness) to evaluate your plant, you may want to start considering it. OEE uses logical equations to track your plants losses machine by machine. This includes downtime, speed, and quality. Downtime can be scheduled or unscheduled. This post will go over the benefits and cost savings of OEE.
In previous blogs I have touched on the equation for OEE and explained it more in depth. This article is more specifically targeted at improvement to availability and performance through reducing downtime. To calculate your OEE and find ways to improve, you will need to keep records of your production and downtimes.
The equation for OEE is: OEE% = Availability rate * Performance rate * Quality rate.
This leads to three more equations for each rate:
- Availability Rate = Available Time (total working time - start up and shutdown time) / Scheduled Working Time
- Performance Rate = Actual Output (running speed) / Standard Expected Output (maximum effective speed)
- Quality Rate = Customer Usable Produce / Total Output Product
As you can see by the equations above Availability and Performance make up 2/3 of your OEE score. Addressing them can help remedy a large portion of your losses. Another thing to notice is that Availability is the percentage of the expected work day that you are actually working. This means that if you expect a 10 hour shift but start up and shutdown takes away half an hour of this; and breaks take another half hour, then you are only getting 90% in Availability.
What is Downtime?
We can start addressing these areas by looking into downtime. Downtime can be broken down into scheduled and unscheduled time. Unscheduled down time logically seems to be worse, and typically is because it always takes away from production time. However, scheduled down time that keeps you from producing when you could be is also detrimental to your OEE score. If your company is taking scheduled breaks, and a competitor is not, then you are giving away an opportunity to stay competitive in the market.
Software Tracking Devices
OEE helps pinpoint your main sources of downtime so you can address the problem at its source. It may be worth looking into a software tracking system to help with this process. OEE tracking software will easily pay for itself with the losses it will find and allow you to reduce or even eliminate these losses. Finding and fixing these problems helps put more money into your pockets in the long run. It can track delays of even a few seconds that would go unnoticed by any worker or manager. This also leads to isolating machines that are not up to par with the rest of the plant.
Using tracking software also allows you to differentiate between scheduled and unscheduled downtime. If your scheduled downtime is larger than your unscheduled, this is something that should jump out to you and you should look to change quickly. If not, then it gives you a starting point to address your unscheduled downtime. This could mean preventative maintenance or even replacing an old machine if the losses are great enough.
Tracking software is just the beginning of tracking your downtime. To look into even more ways to reduce your downtime check back for part II.