Overall Equipment Effectiveness. Robert Hansen C.

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СКАЧАТЬ target="_blank" rel="nofollow" href="#fb3_img_img_5127da67-fbf8-5a0b-918a-316d1ae686c3.jpg" alt="image"/>Overall Equipment Effectiveness (OEE). How effectively (makes good product at rated speed) the process runs when it is scheduled to run, see section 2.5 for the formula.

      Operating Time. Also called Runtime or Uptime. The portion of loading time when the system is actually making product.

      Quality Rate. The number of good units divided by the total units produced. The rate can be measured by items, square feet, cubic feet, gallons, barrels, etc.

      Quantity of Good Product. Product that conforms to specifications. This count should not include volume that is on hold or may be condemned. Product that is transferred and later found to be No Good (NG) should be included under Waste (see below). However, if the loss is due to a specific root cause, then that loss should be noted in the comments under Waste. (See the example in the report, figure 2-5).

      Speed Loss. The percent reduction of OEE due to running the equipment slower than Ideal Rate for the size and format or product family. It represents the difference between the theoretical time for the rate or cycle and the actual time used to make the product.

      Stop Time (ST) can be Planned or Unplanned.

      ST Operational. Planned stop time. It includes operational actions such as product changeovers and size changes, as well as standard testing, planned material loading, and required documentation.

      ST Induced. Unplanned stop time when the line is down due to external (non-machine) reasons such as lack of materials and supplies, lack of people, lack of information, and unplanned meetings.

      Theoretical Rate. See Ideal Cycle Time.

      Theoretical Run Time. This is the minimum amount of time to produce the amount of good product. It is equal to the amount of good product divided by the ideal cycle time.

      Total Effective Equipment Performance (TEEP). The percent of Total (calendar) Time the equipment runs at ideal speed making good product.

      Total Time. Every minute of the clock. For a year, this measure is total calendar time (60 min × 24 hr × 365 days); sometimes called Calendar Time.

      Waste. The total waste rate of the normal process. This should include structural waste, incident waste, testing waste, and recall waste. Unplanned waste that is generated while running the equipment should be captured here with a reference to the root cause of the incident. (Note: Companies often exclude structural waste to avoid visibly acknowledging its existence.)

       2.2 Data Collection Review

      Data collection and analysis for OEE is sometimes thought of as good in theory but not in practice. The arguments against it use excuses such as “We have too many different products” and “Our process is changed for different style outputs.” In these situations, the best approach is to step back and review the boundaries of the system. Start where materials are input into a systematic flow with an expected product or subassembly for the next factory step. This transformation step is often linked with others in a series of steps that have few if any fixed buffers. The process has an expected flow or cycle time.

      OEE is appropriately applied to bottlenecks, critical process areas, and high expense areas. An appropriate test is to ask, “If the effectiveness of this transformation step is improved, will the bottom line be significantly impacted?’ If the answer is yes, then putting effort into generating true OEE and driving improvement is worthwhile.

      As an example, I once observed a work center that successfully used OEE on the shop floor as follows. The company was highly automated; it used shop floor computers to gather much of its information. Its Equipment Performance System (EPS) collected not only the various downtime causes and frequencies, but also run time and speed monitoring. From this database, the company could easily compute OEE for each product.

      Essentially, the company picked a standard process that represented its most common product. This product-process format was used as the benchmark for OEE. Because the format was used so routinely, significant production history was available. Furthermore, the product was manufactured on all of the work center’s different equipment flowlines. Next, the work center defined how other formats and sizes with the same product should compare with the benchmark process. This comparison generated an OEE coefficient. The comparison was repeated for different product families and formats as well as for different process setups. The information gathered was valuable when communicating with superintendents and plant managers about capability questions and the impacts of different product mixes. It also provided the yardstick for shop floor crews to use when examining their real time productivity on shifts.

      This plant had the advantage of having automatic data monitoring and information feedback for nearly all the products it produced. However, at the very minimum, plants can simply gather the information for each product run, usually manually from cycle counters, run hour clocks and other measuring devices. Simple chart recorders can be extremely valuable because the frequencies and duration of events can be easily captured and analyzed.

      Figure 2-1 provides a form that lists the minimum information that should be gathered.

      This information collected for each product run can quickly form the database to begin examining OEE and to start driving productivity improvements. For example, comparing start/stop time vs. run time measures efficiency, start/stop cycle time vs. run time measures speed information, and units vs. transferred output measures quality. Comparing input materials vs. units produced captures waste and inventory information. Comments from the crew leader help cross-functional teams work on root cause elimination of limiting problems. One goal is to understand the actual functions that have failed, as well as the actual equipment and technical problems. Another goal is to reconcile the actual output with the computed OEE, confirming that true OEE is being captured.

Figure 2-1 Example Run Order Report Form

      A decision must be made about how to handle re-work. In many processes, manufactured items cannot be transferred or shipped with out being re-worked first. (In such cases, the first effort of bottleneck has failed. OEE for that manufacturing time is zero.) Re-work efforts can fall into the following three categories.

      1.The re-work can be СКАЧАТЬ