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66 SMT007 MAGAZINE I MAY 2018 Factory Energy Consumption Today, energy efficiency is an important requirement for any manufacturing facility, as a large percentage of a factory's operating costs go into paying for electricity to both run the equip - ment and keep the facility cool. Figure 4 shows a breakdown of where energy is consumed in a typical EMS manufacturing factory in a warmer climate on products requiring post assembly burn in and reliability screening using thermal cycle chambers. It should come as no surprise that the energy required to run the air condi - tioning to keep the factory floor cool far exceeds that required to keep both the front SMT and backend test operations functioning. The greatest potential for energy savings will therefore be realized from being able to mini- mize the amount of air conditioning which is required. Now most factories are setup from an air handling perspective to provide uniform cooling throughout the facility with a few stra- tegically placed thermostats on the floor to dictate the cooling demand required. However, what generally happens is that the stress chambers are undercooled due to the local- ized concentration of heat generating sources, while areas further from the chambers are over- cooled. The net result is uneven cooling across the entire factory, resulting in wasted energy. In an ideal scenario, cooling would only be provided to exactly where it was required and when. Also, production equipment could be shut down or put into stand-by mode when not needed instead of unnecessarily consum- ing power and venting heat into the factory. Dynamically controlling power consump- tion by systematically powering down inactive parts of a line during breaks in production is a key element of Industry 4.0. However, the entire planning and operation of the produc- tion facilities must be designed with this capa- bility in mind to be able to meet this require- ment. Currently, many production lines or parts thereof continue running and consum- ing high quantities of energy during breaks, weekends and shifts where there is no produc- tion. In a recently published case study at an automotive assembly line, nearly 12% of the total energy consumption of the vehicle body assembly line that uses laser welding technol- ogy occurs during breaks in production. The line operated five days a week on a three- shift pattern. Although this complex piece of machinery is not in use over the weekend, it remained powered up so that it could more quickly resume production once the week- end is over. If the source of the 12% energy consumption was further broken down, 90% of power consumption during breaks in production was accounted for by the follow- ing: robots (20–30%), extractors (35–100%) and laser sources and their cooling systems (0–50%) [1] . In this vehicle factory example, several steps could immediately be taken to help improve the energy efficiency of the opera- tion: the robots could be powered down as a matter of course, even during short breaks in production. During longer breaks in produc- tion they could enter a kind of standby mode known as wake-on-LAN. The extrac- tors could use speed-controlled motors that could be adjusted to meet require- ments instead of motors that cannot be controlled. In the case of the laser sources, completely new systems were the only way of delivering improve- ments. Taken together, these measures enabled a reduction of 12% of total energy consumption to be achieved, together with a 90% cut in energy consumption during breaks in produc- tion [1] . However, the full extent of the potential gains cannot be met until Figure 4: Energy consumption by type.