Assembly - November 2008 - (Page 44) Automation Systems Overall Equipment Effectiveness Overall equipment effectiveness (OEE) addresses three categories of productivity during the time a process is scheduled to run: availability—is your process running; performance—is it running at rate; and quality—is it producing a quality output? Let’s evaluate the OEE of a process with an ideal throughput rate of 20 units per hour, running in a plant that is open three shifts, five days, 50 weeks per year (3 x 8 x 5 x 50 = 6,000 hours). The process is scheduled to run 5,400 hours per year, but actually ran 4,425 hours, during which it produced 69,000 units, 257 of which were rejects or required rework. Is it scheduled to run? Plant operating time is the time your plant is open and staffed. The time your process is not scheduled to run is planned shutdown. Planned shutdown includes breaks, scheduled maintenance, and time during which there are no orders to run. Planned production time is the base time used for OEE calculations. Planned production time = plant operating time – planned shutdown time In our example, planned production time = 6,000 – 600 = 5,400 hours Is it running? Availability addresses downtime losses. Downtime includes all events that keep a process from producing for a significant length of time, such as changeovers, material shortages and equipment failure. Operating time = planned production time – downtime In our example, operating time = 5,400 – 975 = 4,425 hours Availability = operating time ÷ planned production time In our example, availability = 4,425 ÷ 5,400 = 0.819 Is it running at rate? Performance is a measure of process speed loss. Speed loss includes the relatively short-term events that make your process run at less than its ideal rate, such as operator errors, substandard material and machine wear. Performance = total output ÷ operating time ÷ ideal rate In our example, performance = 69,000 ÷ 4425 ÷ 20 = 0.78 Is it producing a quality output? Quality as it affects OEE is a measure of the output that does not meet quality standards; specifically, the ratio of good output to total output. Quality = good output ÷ total output In our example, quality = 68,725 ÷ 69,000 = 0.996 What is the OEE? OEE is the quantity of good output produced during the planned production time, divided by the quantity of output expected during the same time period, which is the ideal rate multiplied by the planned production time. In our example, OEE = 68,725 ÷ [20 x 5,400] = 0.636 or 63.6 percent. Another definition for OEE is the product of availability, performance, and quality. In our example, OEE = 0.819 x 0.78 x 0.996 = 0.636 or 63.6 percent. The world class figure for OEE is generally considered to be greater than 0.8 or 80 percent. Technifor Direct Part Marking and Traceability Micro-Percussion Scribing Laser Marking Contact us for in-plant analysis and demos. Tag Marking 2D Coding & Reading 800-394-9101 Technifor, Inc. Tel. 704-525-5230 Fax. 704-525-5240 e-mail: tfinc@usa.technifor.com Please don’t assume there is fat in our price to cover additional requests you might make. Our quoted price covers our expenses and includes a modest profit margin that allows us to keep our prices competitive, and allows us to survive and grow. Our expenses include engineering time, fabrication labor, assembly and debug labor, travel expense, incoming freight, purchasing of commercial and fabricated machine parts, benefits, insurance, taxes, building maintenance, utilities and administrative overhead. Our quoted price will be held for a finite term. The prices we pay for wages, benefits, materials, parts, services and even taxes are fluid. These prices form the basis of the prices we charge for our products. Please don’t dust off a year-old proposal and assume we will honor it. We may honor it, but we may not be able to. Design and Build In our proposal, we described a concept for your project—not the only possible concept—but a concept that we are certain will work. Some www.technifor.com UID Compliant 44 ASSEMBLY / November 2008 www.assemblymag.com ASB06074Technifor.indd 1 5/3/07 10:59:44 AM http://www.technifor.com http://www.assemblymag.com
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