One of the greatest struggles for any manufacturer is knowing what is actually happening on the shop floor. Machine monitoring systems allow manufacturers to collect the critical data that gives department heads, supervisors, and operators real-time information about shop-floor activities, enabling them to make faster, more confident decisions.
If the objective of machine monitoring is to understand current performance, measure that performance over time, and then improve on it, one must first define performance.
The most commonly used metric to do so is OEE (overall equipment effectiveness). As is the case with many performance metrics, OEE is often misused and misunderstood.
While OEE will help you identify potential losses and understand where your process is falling short, it's so much more than just a performance metric; it's the cornerstone of a continuous improvement strategy.
First, let’s talk about what factors into your OEE calculation:
Simply put, OEE measures the efficiency of a machine. OEE takes into consideration the Availability, Performance, and Quality of a machine.
In mathematical terms, OEE = Availability * Performance * Quality
For the purposes of calculating OEE, the underlying metrics are as follows:
Availability - Availability can also be referred to as Uptime. This is the amount of time the machine is in cycle producing parts compared to the amount of time the machine is scheduled to be in cycle. Any unplanned downtime will result in a lower availability percentage. The main factors that hinder machine availability are:
→ Equipment Failures (Breakdowns)
→ Machine Set-Up and Adjustment Time
Performance - Performance refers to the speed that parts are produced while the machine is in cycle. It is calculated as the average in-cycle time to produce a part divided by the ideal in-cycle time to produce a part. The more parts produced within a period of time, the higher a machine's performance percentage. Key factors that negatively influence performance include:
→ Machine Idling and Minor Stoppages
→ Reduced Speed of Operation
Quality - The quality metric is the percentage of good parts out of total parts produced. Any parts rejected during a run will lower the quality percentage of a machine. Some of the primary reasons for quality reduction include:
→ Process Defects
→ Reduced Yield (from startup to stable production)
What is an OEE score?
- An OEE score of 100% is perfect production; this requires only manufacturing good parts, as fast as possible, with no unplanned downtime
- An OEE score of 85% is considered world class for manufacturers. For many companies, it is a legitimate and reasonable long-term goal.
- An OEE score of 60% is fairly typical for manufacturers, but indicates there is room for improvement.
- An OEE score of 40% is common for manufacturing companies that are just starting to monitor and improve their manufacturing performance. In most cases, OEE can be easily improved just by monitoring your machines and learning where the inefficiencies lie within the manufacturing process.
OEE and Machine Monitoring:
Manufacturers typically work quickly to identify and solve problems, but fail to take the time to understand what is at the root of the problem. Knowing how to calculate and optimize your OEE can provide answers to both the big picture problem and the details surrounding the problem.
The first and most important step to improving OEE is the integration of a machine monitoring system onto your shop floor. This will provide the production visibility necessary to boost OEE. MachineMetrics monitoring software enables manufacturers to not only determine their current OEE, but to use it to identify potential problems and understand where your processes are falling short. Is it performance, quality or availability?
OEE is much more than just a performance metric; it is the cornerstone of a continuous improvement strategy. Visionary leaders can utilize OEE to proactively identify issues and promote accountability on the shop floor. Understanding and utilizing OEE can help align the goals of both senior management and plant floor operations. This alignment will encourage all employees to be more proactive, and through this collaborative process, productivity and revenue will increase.