Overall Equipment Effectiveness. Robert Hansen C.

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СКАЧАТЬ between steps. When factory resources are shared, or used in multiple ways, the manufacturing process grows in complexity. The constraint for one product is often different than for other products. The Constraint Management Handbook⁶ is a good reference for understanding and operating the vital steps of manufacturing lines and multiple product orders.

      OEE should first be applied to the bottlenecks that affect throughput or any other critical and costly areas of a manufacturing line. These areas, so vital in making a plant effective, make a significant difference to the company when driven successfully. OEE is beneficial for every step of the process, however, non-bottleneck steps should be subordinated to bottleneck steps.

      Effectively moving a community toward an OEE mindset starts with a company-wide education program that is driven top down. The plant management team must first identify the hierarchy of bottlenecks. Then setting expectations and communicating them to the plant employees launches the initiative for a successful change. OEE should work synergistically with the financial information for each product. When OEE is used by management as the key metric for a factory’s vital points, and each person’s performance appraisal is linked to improving the metric, an effective factory evolves quickly.

      True OEE multiplies factors that represent availability, speed, and quality. The result can be expressed as a percentage of effectiveness that directly correlates with actual factory floor output, and can be reconciled 100 percent. This will be demonstrated in the Case Study that follows.

      Understanding the correlation concept is key to having a single metric that has credibility with the production, maintenance, engineering, management, and financial areas.

      OEE can be generated easily and accurately; it can quickly demonstrate the size of the hidden factory in your specific area. In turn, the plant leadership team can apply people and resources to the proper locations for the fastest improvement.

      Chapter 2 will provide a practice example including recommended definitions, a sample production period, and a total range of incidents. In developing the OEE formulas, it will demonstrate that the three different approaches provide exactly the same OEE. Even areas without detailed data collection can still use the simplest method to calculate an accurate OEE.

      All manufacturing areas should be able to answer the following questions for each product:

      1.How many units that meet specifications were made and transferred to the next step?

      2.How much time was scheduled for production of that product?

      3.What is the ideal or best theoretical cycle time or throughput for units of that product? (If this were unknown, a rough approximation would be to use the speed value generated by the best 4 hours of the last 400 hours.)

      With this information, the simplified calculation shown in section 2.5 can generate an accurate OEE for each product. Prorating the individual product’s OEE can generate a combined OEE for the area. I recommend prorating by the percentage of production schedule time used to make specific products. Even areas with good data collection should reconcile OEE by using the simplified method. All methods should reconcile. If they do not, assume the lowest value is correct and that the other methods have overlooked an area of opportunity. Remember, true OEE directly correlates to area output.

      After analyzing all major processes and important equipment systems for each plant site, summarize the results from each area as follows:

      < 65% Unacceptable. Hidden dollars are slipping away. Get help now.

      65-75% Passable, only if quarterly trends are improving.

      75-85% Pretty Good. However, do not stand still; continue to drive to a world-class level. (>85% for batch type processes and > 90% for continuous discrete processes. Continuous on stream process industries should have OEE values of 95% or better.)

      Ron Moore of the RMGroup Inc. related to me his best OEE experience was a client with a verified on-stream OEE of 98% over a two-year period.

      Using OEE metrics and establishing a disciplined equipment performance reporting system will help any manufacturing area to focus on the parameters critical to its success. Analyzing OEE categories can reveal the greatest limits to success. Forming cross-functional teams to solve these root problems will drive the greatest improvement and generate real bottom-line earnings.

      The vast majority of these improvements usually come from non-capital projects. Changes to basic procedures often reduce bottlenecks. Changing supply or distribution policies can help manage bottlenecks. Significant equipment reliability improvement may result by changing maintenance methods or substituting different materials. Focused projects, such as Reliability-centered Maintenance⁵, can provide major increases in uptime. Improving performance through OEE involves several steps:

      1.Calculate the OEE value for current performance (see method 3 in section 2.5).

      2.Use discipline and be honest with the results. Compute the financial opportunities of improved throughput (use the model provided in chapter 3). Generate a realistic business plan of closing the OEE gap to world-class levels for your type of industry. At this point, accept the assumption that improvement programs will consist primarily of education efforts and focus teams collecting/analyzing data for root causes. Minimal capital is required and existing resources are usually adequate. Training time and participative education on improvement methods contained in this book are often 90% of the investment.

      3.Assuming that the size of the opportunity is significant, commit to a pro-active agenda. Define the hierarchy of critical processes and bottlenecks. Set expectations for plant goals and rewards. (This step may require changing existing measures and reward systems.) Once the key bottlenecks are identified, they must be tackled. OEE and Constraint Management methods should work in synergy.

      4.Once the goals are defined, and a plan for addressing the bottle necks is established, share this vision with the workers. Communicate the significance of the improvement and give the community a compelling reason to make the changes. At this time, identify the reward structure.

      5.Educate all members of the community about OEE measures and how to collect and reconcile the information. For example, counters, time clocks and chart recorders may be needed on key equipment systems. Reports may need to be modified to categorize downtimes. Everyone should have a major portion of their performance appraisal and compensation linked to achieving the OEE goals. By understanding the categories for data collection and how losses impact OEE, synergistic teams will form. These teams can quickly eliminate root problems. Associated departments can support additional improvements.

      6.Generate the resources (e.g., money, people, time, and training) to make the changes happen. Introduce new techniques and programs, as appropriate, including condition-based, predictive maintenance and reliability programs, Total Productive Manufacturing and Best Practices techniques, Statistical Process Control, mistake proof and fail safe techniques, supplier quality requirements and follow up, and quick changeover techniques for operations and maintenance repetitive tasks.

      7.Use the OEE metrics at all levels of the plant. Share the results with all parts СКАЧАТЬ