Speed loss in manufacturing facilities has received less attention than downtime, but the effect of speed loss on overall equipment effectiveness (OEE) may be as much as 15 percent. This is because speed loss is a hidden and complicated problem that is often underestimated by managers.
Research indicates that you can reduce speed loss by reorganizing production lines, and improving working practices or production schedules.
What Is Speed Loss?
Speed loss can be categorized into two types: slow speed and micro stops.
Slow speed occurs when equipment operates below the target rate
Micro stops are brief stoppages on a machine or production line
The term speed loss can have different meanings depending on who you ask. One way of defining it is as a synonym for performance loss, which is one of the three categories of OEE losses (all three being availability, performance, and quality).
The Six Big Losses framework is aligned with OEE loss categories, which are: Availability loss, Performance loss (same as speed loss), and Quality loss.
Each category has two more sub-categories:
- Availability loss
- Planned stops
- Unplanned stops
- Performance loss (same as speed loss)
- Micro stops
- Slow cycles (same as slow speed)
- Quality loss
- Start-up rejects
- Production rejects
Speed loss in Total Productive Maintenance (TPM)
Speed loss is also part of the TPM framework. The terms used are slightly different:
- Minor stoppages & idling (same as micro stops in the Six Big Losses framework)
- Speed loss, reduced speed (same as slow cycles in the Six Big Losses framework)
Why Are Micro Stops Classified as Speed Loss, and Not Downtime?
When a production line stops, it is referred to as downtime or stoppage time. When micro stops occur during downtime, they are classified as availability loss. However, if micro stops occur while the line is running, they are classified as speed loss.
There are a few reasons for this:
- The reasons for micro stops (delays in production) overlap more with problems at slow speeds rather than downtime.
- Reducing micro stops requires similar solutions to reducing slow speeds.
- Downtime is frequent and obvious, while micro stops are more common but less noticeable.
Examples of Micro Stop & Slow Speed
Typical causes of micro stops are:
- Equipment misalignment, poor positioning
- Incorrect settings
- Blocked sensors
- Material miss-feeds and jams
- Equipment design issues
- Periodic quick cleaning
Typical Reasons for Slow Speed
1. Technology factors
- Reliability of technology (machine reliability, equipment wear, improper maintenance, production stops)
- Technology limitations (incapable equipment, equipment wear, queue capacity for work in process)
- Environmental limitations
2. Human factors
- Operator inefficiency (i.e., due to lack of training)
- Measurement error
- Planning issues (ideal cycle time set too low or target too unambitious, production scheduling, capacity utilization issues)
