Reduced Electricity Use Translates to Reduced Production Cost and Lower Carbon Footprint
Delta Group Electronics, Inc. is a high-mix, low-volume electronics manufacturing services (EMS) provider that serves the telecommunications, capital equipment, defense and aerospace industries. The company’s main focus across its five facilities is to provide cost-efficient, high-quality assembly for customers.
The fact that the electronics manufacturing industry is extremely competitive and becoming more so is well established. The strategies to not only survive, but to thrive in this environment are less well known. One tendency among manufacturers may be to spend as little as possible to save oneself to prosperity. Delta Group Electronics, however, realizes that thrift is essential but not sufficient to succeed in this industry. We need to invest smartly to meet our commitment to our customers for high-quality and cost effective production. There is no single magic formula for this but rather a series of continuous improvements whose cumulative effects make a difference.
At the Arkansas Delta Group Electronics plant, we decided that one of the steps to further competitiveness was to invest in technologies to reduce electricity consumption. The company’s reflow ovens represent one of the biggest users of electricity in the factory, so this was a natural focal point. There are several thermal process optimization tools on the market to aid manufacturers in setting up their reflow ovens in the “sweet spot” of the thermal process window. Only one of them, however, advertised its capability to include electricity use as an optimization criteria. We decided to acquire one of those, but we wanted to verify the real capability of the system ourselves.
The first step in our project to measure savings in electricity was to hook up a Power Meter to one of our reflow oven’s power supply. We continued our production run in the reflow oven using the same oven recipe that we had always used for this particular application (Assembly 1). A reflow oven is a dynamic machine that automatically turns its heaters on and off to maintain the selected set points. Hence, its power use changes constantly. The meter that we used did not have sophisticated analysis capability of the data, so we manually recorded its readings in an Excel spreadsheet every few seconds until we had a sufficient number of readings. We then ran a thermal profile with thermcouples attached to our Assembly 1, and we KICked off the KIC Navigator Power optimization software to search for a more optimal oven set up. High-quality production is paramount at Delta Group Electronics. Therefore, we set the “KIC Navigator Power” search criteria to find an oven setup with lower electricity use, as well as one that would yield a profile deep in spec. The third recipe search criteria was to consider conveyor speeds above the level at which the reflow oven would become the bottleneck. It was an easy task to define the slowest process in our production line, and to calculate the equivalent reflow oven conveyor speed.
Once the criteria were set it took only a few seconds for the software to recommend a new recipe. Since we were using a software simulation of what profiles each new setting in the oven would yield, we wanted to verify the accuracy of the results. We did this by selecting the new recipe and waiting for the oven to stabilize. Once the oven stabilized, we ran another profile of Assembly 1. Our new profile was actually far deeper into spec than the original, so we were satisfied that our quality would be as good or better than before. Once the production resumed, we recorded the readings from the Power Meter again. We repeated the above procedure for a different PCB assembly (Assembly 2).c
Electricity Use Analysis Power consumption (Kilowatt Hour – KWH) data was collected for all batches of PCB assemblies that were run through the process. The graphs below show box plots of the power consumption data and compare the original recipe with the optimized recipe.
The box plots, in general, reveal the upper limit of the data (top end of the whisker), lower limit of the data (bottom end of the whisker), a quartile box (showing the spread of the data observed), the mean of the data (dot) and the median of the data (horizontal line within the quartile box). The following are key observations from the box plots of the run data:
- The optimized oven recipe showed a 15.8% reduction in power consumption for Assembly 1 and a 13.6% reduction in power consumption for Assembly 2.
- No outliers were observed in the data sets for both assemblies, indicating no abnormal observations during the runs.
- For both assemblies, the spread in the observed data was reduced for the optimized oven recipe (21% for Assembly 1 and 17.7% for Assembly 2), when compared to the original oven recipe. This possibly indicates that the oven performance was more uniform with the optimized profile.
- The upper and lower limits of the whiskers for the optimized oven recipe, for both Assembly 1 and Assembly 2, show a more balanced (tighter) power consumption pattern for the oven when compared to the original oven recipe. This balanced power consumption pattern could lead to extended life of the heater elements in the oven.
Delta Group Electronics focuses on reducing cost and carbon footprint, as evidenced by the wind turbine installed next to its factory.
Conclusion
Introduction of a simple process optimization software resulted in an immediate reduction of the reflow oven electricity use of 13.6% and 15.8% respectively for our two PCB assemblies included in the test. This gain did not come at the expense of either productivity or quality. Actually, the profile was positioned deeper in spec during this project, indicating that the process became more robust.
There is no such thing as a “free lunch”-after all we had to pay for the marginal cost of the process optimization software-but this does come very close. Prior to KIC’s new approach, no one had been thinking about electricity consumption when selecting an appropriate reflow oven recipe, and the odds were that the oven would be running too hot in one or more zones. The KIC Navigator Power uses a scientific method to optimize electricity use and, hence, takes any slack out of the oven recipe. That optimized equation converts directly to energy savings.
Mike Payne is general manager of high-mix, low volume electronics manufacturing services provider Delta Group Electronics. Based in Albuquerque, New Mexico, Delta Group also has assembly operations in Florida, Texas and Arkansas.