Circuits Assembly - September 2008 - (Page 38)

Cover Story Improving OEE in High Mix Facilities By States Mead Switching to small lot sizes has killed my line utilization. Help! T he decision by EMS firms and OEMs to reduce lot sizes on the plant floor to respond to order changes comes at a hefty price. With margins already razor thin, increased changeover frequency fuels the fire, as planned downtime rises and asset utilization falls. The probability of quality issues also increases as the number of opportunities for error during setup occurs. This growing negative OEE (Overall Equipment Effectiveness) trend can be seen throughout facilities in North America. Facilities once running world-class OEE rates (above 85%) now fall below 70%, even 50%. The shift of large-volume production overseas has created an adverse effect to OEE. Changes are made on the production floor to satisfy requests for smaller lot sizes, faster turn time and schedule flexibilities. Balancing these changes, manufacturers need to address the side of the OEE equation they can control: their process. Often, Table 2. Current Revenue however, limited resources and funding allocations result in long-term damage to the manufacturer’s profitability. Pretend, for a moment, you are plant manager for Company ABC and have instructed your engineers to improve cycle time by 10%. Will that alone improve OEE? Not likely, but let’s prove it. As everyone in the Lean world knows, OEE = Availability x performance x quality Another way to look at it is: OEE = Good pieces x ideal cycle time / Planned production time Assume manufacturing requires a changeover (C/O) time of 20 min. from model A to B, and the current cycle time (CT) for both models is 1 min./panel. The current lot size is 200 boards, with about 10 min. of unplanned downtime (DT) during production during each run. The current OEE is around 87%. With a 10% cycle time improvement, OEE becomes 86%. That’s not much of a change, and probably worth the investment to increase throughput capacity. But what happens when the lot size is reduced to 100 Table 3. Proposed Revenue Opportunity Proposed Run Hr./Mo. SMT 2 SMT 3 SMT 4 Total new hr. available Average $ value/board Added potential revenue/mo. Added annual potential revenue Potential revenue % increase 180 145 135 119 $75 $535,000 $6,426,000 20.60% Table 1. Improvements in Program Cycle Time Product Family A Reduction in changeover carts Reduction in changeover time Reduction loading parts onto feeders Reduction in cycle time Increase in line capacity 50% 33% 40% 10% 10% Product Family B 50% 33% 40% 10% 18% Product Family C 25% 33% 35% 9% 15% Current Run Hr./Mo. SMT 2 SMT 3 SMT 4 Average $ value/board Average cycle time (min.) Total revenue $/mo. 200 200 179 $75 1 $2,605,500 38 Circuits Assembly SEPTEMBER 2008 circuitsassembly.com http://circuitsassembly.com

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Circuits Assembly - September 2008 Contents Caveat Lector Industry News Market Watch Talking Heads Focus on Business Global Sourcing On the Forefront Screen Printing Better Manufacturing Reflow Soldering with a SnCu Eutectic Pb-Free Alloy Improving OEE in High Mix Facilities Effectively Managing RF Design in Utility Metering Applications Solder Joint Reliability of Different BGAs Reworked Using Low Melting Point Pb-Free Alloys Tech Tips Wave Soldering Pb-Free Lessons Learned Materials World Process Doctor Equipment Advances Product Spotlight Ad Index Assembly Insider Technical Abstracts

Circuits Assembly - September 2008

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