Reading time ( words)
Automation for PCB assembly processes in 2016 is a world away from where it started in the 1990s, when high-volume production was still enjoyed by most operations. The idea of replacing remaining manual operations with automated processes that offered a compelling return on investment, reduced variation, and higher reliability seemed like a great idea, although the technology at the time did not quite deliver on expectations.
Fast forward to today, and the same ideas and goals for automation are once again in play; but this time, although technical capabilities have vastly improved, little high-volume is left. Automation now has to be part of a high-mix production environment, with flexibility as factories are called on to be more responsive to shorter term changes in demand. Manual processes are the most flexible of all, so now the stakes for introducing automation are higher.
This high-mix environment has created an irony in PCB assembly manufacturing with SMT. Automated SMT machines are faster and smarter, with wider capabilities and efficiencies, and they are generally more flexible in how they can be used. However, some engineers are embarrassed when showing visitors (or top management) around the SMT area because many of the machines appear to not be working. Productivity levels of higher than 80% are commonly reported, which would imply that the machines should be working 80% of the time; but this is clearly not the case, especially when visiting any factory doing high-mix production. When calculating the absolute productivity, or asset utilization, the figures are actually closer to 40%.
No matter what effort a factory makes, the absolute asset utilization of SMT machines and other related complex processes declines sharply as the number of product changes increases. This decline is caused by the extensive setup time when changing between different models. With the trend of increasing product mix and decreasing lot sizes, the problem is growing worse…and it’s not going away. The fluctuation of customer demand is brought more directly to the factory, as the stock holding in the distribution chain is reduced to save significant costs to the overall business. If we are to introduce further automation into PCB assembly, we must be able to achieve the return of investment goal that it should be capable of while making an automated factory that is flexible and efficient. And to do this, we need to once and for all resolve the issue of decreasing productivity.
Editor's Note: This article originally appeared in the March 2016 issue of SMT Magazine.