Since the 1970s, an increasing number of manufacturers have used the three components of availability, performance, and quality to calculate the overall equipment effectiveness (OEE) for determining how well a process is running. OEE is also used to identify areas of improvement. Understandably, most manufacturers target the more prominent areas of concern, which will generate a more dramatic or marked improvement.
However, there is always room for improvement, and effective OEE identifies and targets both dramatic and incremental improvements. And while OEE is a metric expressed as a percentage, it isn’t difficult to translate it into a dollar amount. When a single percentage point might be worth hundreds of thousands or even millions of dollars, incremental changes start to take on more relevance. Whether a manufacturer is just beginning to calculate OEE or is reaching for a few percentage points of improvement, examining the following three hidden gems of OEE potential, startup loss, changeovers, and brief stops, will yield quantifiable benefits.
1. Startup Loss
When manufacturers are looking for hidden losses, a great place to start is at the start. During startup, the three main components are variation in standards, the first hour, and speed and consistency. Startup losses can occur due to operator error or well-intentioned operators making decisions outside of standards.
Variation in Standards
It is normal to discover that line operators interpret and apply standards for pass/fail or other quality standards differently. When tracking OEE, look at the differences between shifts to determine what the highest performing shifts are doing right and what the lagging shifts can improve upon. Other issues include when different operators do not apply standards uniformly across the shifts or when inspectors use their own standards.
Often a simple resolution is to identify training opportunities. If two lines are running at a high level and a third line is much slower, it may be as simple as an employee applying standards too rigidly and could benefit from additional training. Newer employees can shadow more experienced employees to understand better how to use standards.
The First Hour
If tracking hour-by-hour charts is a challenge, managers can still gain a lot of insight by examining the last hour and first hour of a shift since those transition periods are when there is the most significant potential to lose the most OEE improvement. Within the first hour, it is not unusual to discover numerous inefficiencies. Operators may feel they need to tweak the process or deviate from standards.
One example of an operator deviating from standards with good intentions would be allowing a machine to ‘warm up’ beyond the standard amount of time or running a line at a reduced speed, even if standards indicate the process does not require this. Some machines need to warm up to operate correctly, but beginning this process while employees wait for the line to produce impacts OEE. If operators make changes to equipment settings in the first hour and do not document it, then this can alter OEE.
Another first-hour issue happens if a line is part of a Monday morning set up after a weekend close. An improper close can impact the operators’ ability to start the line promptly. One issue that some industries experience is related to heavy regulation. A line may need to run a test part which must pass inspection before the line starts up for total production. A significant time loss can occur if the inspector is not near the line while the operator tracks down the inspector for approval.
Speed and Consistency
Sometimes machines have issues due to operator error, like bringing the temperature up too quickly or due to other maintenance needs. Both of these problems can produce an inconsistent product or intermittently affect speed. A poor close of the line or machine by the last shift will impact the next shift’s ability to startup on time. Similarly, the startup will not proceed efficiently if the operators fail to follow procedures. Operators may attempt to shortcut procedures because they think it speeds up the process, but by skipping some steps, other issues can occur, slowing the line down later.
Plants that produce different products on the same equipment or run various equipment within the same facility to produce multiple products will also see this complexity reflected in their OEE score. Finally, many facilities make assumptions about processes and may actually be accepting significant speed loss without realizing it. If managers never examine equipment and processes in terms of OEE, they are missing opportunities to identify and resolve hidden issues.
Many of the actions that negatively impact OEE come from a well-intentioned place or based on a previous experience.
The amount of time it takes a facility to make unavailable equipment available for production is called a changeover or sometimes planned downtime. While changeovers are unavoidable, there are ways to refine the length of time a changeover takes, returning that time back to active run time. Changeovers are affected by scheduling both within the facility and throughout the value chain, setup, and ramp-up.
- Scheduling: Scheduling optimizes efficiency and productivity. Scheduling throughout the value chain affects OEE. For example, if raw materials do not arrive in time or there are other shipping challenges, OEE may fall as scheduling challenges delay different processes like a domino effect. Losses and pulling forward can also drive rescheduling. Another common issue in changeover is allowing for regular size changes that don’t apply to the pace-setting machine.
- Setup: As improvements occur, it is crucial that managers include the changes and do not neglect to update standard timings based on machine speeds or changeover timing. Regularly checking and updating standards for the allotted changeover time can create a more efficient changeover setup.
- Ramp-up: After setup, another potential time-waster is the ramp-up. Operators may ramp up machines too quickly or too slowly, resulting in poor production or having to reset the process. A non-standards-based ramp-up can also create equipment parts issues. Machines that produce multiple products are also subject to ramp-up challenges if the operators struggle to transition from one product to another.
As mentioned before, tweaks and adjustments can create OEE issues, whether the adjustments are intentional or unintentional. Each shift may make adjustments to the equipment or the process, which affects not only the process but potentially the equipment itself, causing equipment to need frequent calibration or to wear out faster than expected and leading to work stoppage for machine maintenance.
3.) Brief Stops
Brief stops may not seem worth examining since they are more minor issues, but companies that overlook even smaller areas of improvement may struggle to capture the key OEE points they are looking for. Even stoppages of a fraction of a moment here and there will add up over time. Here are three stoppage areas to examine:
- Downstream equipment failures: Downstream equipment may be beyond the core competencies but can still create challenges. If downstream equipment causes a backup, facilities may need to scrap product or even shut a process down until outside processes beyond facility control are corrected. Working with downstream partners or seeking alternative or backup plans can mitigate some of the potential loss.
- Ideal cycle time: All equipment has an ideal cycle time. Operators can be very passionate about their work but may make unnecessary adjustments that deviate from equipment standards and ideal cycle times—and therefore, OEE.
- Micro-stops: Micro stops will add up to significant point drops. Facilities that want to move from good to great must take a close look at micro-stops in their processes. One example of a micro-stop situation is when operators take liberties by performing extra quality checks but not logging those checks. Managers who cannot find those last few points can benefit from tracking real-time data via OEE software and closely watching processes to identify micro stops throughout the shift.
Best Practices for Driving Incremental Improvement
Nothing beats tracking real-time data when it comes to consistent metric monitoring. Manufacturers can track data manually, but many find that this quickly becomes a challenge. Many of the incremental changes essential to pushing for those OEE percentage gains seem to disappear in manual data collection. Implementing an OEE software like SafetyChain provides all the valuable data in a single dashboard and the key performance indicators (KPI) that are most relevant to the manufacturer. While the KPIs that manufacturers track varies from one to the next, all are identifying performance, availability, quality, and yield in some way.
Using OEE software helps managers identify at a glance which metrics are performing above the target and which are lagging. For instance, a manufacturer may be at 91% in quality, 88% in availability, but only 67% in performance. That tells that manufacturer that taking a deep dive into all the nooks and crannies of performance will yield a solid boost in OEE. And once the facility has analyzed performance, it can realize further improvement and added value by tackling quality and availability, even though those numbers were initially much higher. Using OEE as an informative and instructional tool can drive continuous improvement throughout the facility.
Interested in taking control of your OEE, learn more about SafetyChain’s OEE software designed to drive real-time visibility and control for optimal performance in manufacturing.