There are no strict rules to assess machines’ efficiency and no universal cures to fix productivity losses, and each business should decide how to assess its own equipment according to their applications, market, and operating conditions.
Here are the five factors that we recommend considering when evaluating your machine shop productivity.
A machine’s availability score measures how often a machine is available for production. Unplanned equipment downtime, material shortages, and machine changeover are all factors that negatively affect the equipment availability.
To calculate a machine’s availability score, divide the operating time by planned production time.
The performance score is calculated by comparing the number units produced per hour to the number of units that could be produced by running the machine at the maximum rated speed at all times. This is a useful benchmark to assess a machine’s speed loss.
A good way to calculate the performance score is to divide the ideal cycle time by the actual cycle time.
The quality factor indicates the number of good parts produced during the operating cycle. Rejected materials, factory seconds and products that need to be reworked after production can negatively affect a business’ productivity.
4. Big Losses
Most efficiency losses in manufacturing are caused by six subsets of equipment availability, performance, and quality. These are:
1. Planned downtime
3. Minor stops
4. Speed loss
5. Production rejects
6. Rejects on startup
Categorizing incidents into these six subsets can help operators better understand the factors that are affecting plant efficiency.
5. Overall Equipment Effectiveness (OEE)
The OEE score is the direct result of availability, performance and quality scores. You can calculate it by simply multiplying the three factors.
While a single OEE score just indicates what a machine can do better, calculating OEE regularly and assessing trends for individual equipment and the plant as a whole can provide valuable insight into how to optimize productivity.