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16 SMT Magazine • April 2016 so we don't see that unscheduled downtime anymore. Quite frankly, the difference is night and day between our old process and the new process." Prior to the change, the team had been eager to make improvements. While the previous pro- cess was certainly acceptable by most standards, the team wanted to strive for zero defects while at the same time improve cycle times. "We needed to conduct real-time in- spections," says Clarke. "The yardstick we use to measure the effectiveness of the 3D on-board SPI with Closed Loop Control incorporated in the new machine is from the reduction in defects that we see coming off the line. In terms of true defects, we would typically see around 68 ppm with the old screen printing technology. It was untenable. However, with the new screen printer in place, our defects dropped from 68 ppm down to 11 ppm. The change was quite dramatic." Also, economically, the pair were chal- lenged to achieve a cycle time of 15 seconds in order to meet the demands of a new high-vol- ume product being introduced. "Typically your screen printer would at best be able to give you a 30-second cycle time while conducting a lim- ited amount of 2D inspection in select areas. But because we wanted to do a 100% 3D in- spection of our solder paste—and not just a 2D inspection that you would get from most print- ers—this was the road to go down. It would take minutes to really do a complete 2D inspection using our existing screen printer technology. A full-scale inspection would just be prohibitive," notes Clarke. With this new system, Etratech gets all the benefits that the company needs within the 15-second cycle time. In terms of the improvement, Etratech's utilization of the SMT line on which this piece of equipment has been installed is significantly higher. "If we go back and compare downtime that we would have seen on a printer a year or two ago, we're talking about tens of hours of downtime," notes Clarke. "Today, we're looking at uptime on this equipment of around 96%. The metric would be your overall equipment effectiveness (OEE). In terms of a world class manufacturing facility, you want to have util- ization of upwards of 85%, and with this piece of equipment we're boasting an uptime of 96% today. Basically with the greatly improved ppm levels, the repairs are down to next to nothing after Etratech's AOI machine is factored into the process." Previously, Etratech dealt with more mis- prints because the system wasn't capable of self-correction and was prone to washing panels or boards. With this new piece of equipment, the team never has to wash a panel. "Our sys- tem is so repeatable that we do not need to clean boards, but simply pass them back through the system, and that is one of the benefits that we get to enjoy today," says Clarke. lessons learned Etratech became very efficient at supporting an inefficient process. "We actually disguised the inefficiencies in the process by expecting them, and dealing with them so well," admits Renneboog. By re-evaluating the process and the way defects are perceived, Etratech has seen a remarkable improvement in downtime, and a streamlining of its whole production process. SMT Stephen las Marias is managing editor of SMT Magazine. He has been a technology editor for more than 12 years covering electronics, components, and industrial auto- mation systems. in a culTurE of conTinuous imProvEmEnT, ProcEssEs conTinuallY imProvE With the new screen printer, etratech's manufactur- ing team went from receiving process indicators at the end of the line to the new printer actually being able to make adjustments on-the-fly in real-time.