Editor's Note: This article originally appeared in the April 2012 issue of SMT Magazine.
Electronics manufacturing has evolved in the last decade toward a preponderance of high-mix, complex, and low-volume manufacturing from what was once high-volume, “lights out” flow line assembly. High-mix assembly, however, typically requires frequent change-over, particularly in component placement, where different set-ups (components, feeders, and programming set-ups) interrupt production time and result in lower equipment uptime and utilization.
Profit margins have also narrowed; the more productive time lost to set-up and down-time, the less profitable the manufacturing enterprise.
The reduction of changeover requirements is the key to increasing line up-time to bring in more revenue. Planning, consolidation, and elimination of process steps or unnecessary delays also contribute to turning downtime into productive time. The solution is highly flexible equipment with lower changeover needs, driven by powerful software solutions.
Figure 1 shows the necessary changeover times (typical) for a three-module (placement) assembly line, with a 5,120 mm line-length 320 unique feeders/component types. In an all-manual changeover, the required time can be more than 45 minutes. This is not acceptable. Note that the biggest time-waster is feeder cart changeover (two carts per module), accounting for 2/3 of the downtime.
Figure 1: Typical changeover times for a three-module (placement) assembly line.
In a manufacturing scenario where a facility has multiple lines in operation, multiple product line balancing (via software) as a means of production plan optimization can make the operation more efficient and boost up-time. Multi-product line balancing assigns components to selected machines, based on machine capability and speed, to create a more efficient production line. Feeder locations can be assigned by the program for optimum speed, or a common feeder setup can be used. Additionally, two or more existing programs on individual machines can be merged and reallocated for best performance.