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PCB Assembly What Are The Ways Of Introducing
Oct 23, 2017

Electronic product assembly because of its large number of components, a wide variety and short life cycle of electronic products such as the characteristics of the production operation has brought great challenges, many varieties, small batches, variable volume has become the mainstream of electronic manufacturing mode. In this mode, the switching time between multiple varieties occupies an increasing proportion in the whole assembling time.

It is composed of high speed SMT machine and multifunction Mounter. In fact, the entire PCB assembly line also includes the pallet feeder, screen printing presses, dispensing machine, reflow soldering and curing furnace, and other equipment, these devices together to form a PCB assembly line, but these ancillary equipment does not constitute a whole line of bottlenecks in the process, so in modeling to be omitted. Each patch machine can hold 20 slots, each of which occupies a feeding slot on the Mounter. In general, a single variety of PCB circuit boards required the number of components do not exceed the capacity of the feeder, but many varieties of PCB required by the total number of components usually exceed the capacity of the feeder.

In the process of the installation of different types of PCB circuit board required components are placed on these feeding slots, the device from the feeding trough to remove the components affixed to the PCB designated position. According to the investigation data of the empirical research object, the time of the high speed Mounter to mount a component on average is 0.06s, the average time to switch a feeding trough is 180s. Multi-function Mounter has two workstations, but only one work desk, the other is only used for placing large or special-shaped components, each workbench to accommodate 10 of feeding slots, the average mount a component required 0.18s, the average time to switch a feeder is 220s. In different varieties of PCB switching, Mounter need to be ready to switch time, usually to switch a component feeding slot time of about 6 times times, that is, 1200s. Therefore, switching time in the electronic product assembly process has a pivotal position.

In many varieties of small batch environment, the PCB is usually grouped first, will have similar characteristics of the PCB into a group, so that in the same group, different types of PCB assembly between the need to replace the feeder, also do not need to switch time, but when the two sets of PCB between the need to replace the feeder, you need to consider the switching time between them. Accordingly, PCB production scheduling problem is divided into two levels: the first level scheduling problem is called "board-level" scheduling problem, that is, to determine a PCB group in the production sequence between the PCB; the second level scheduling problem is called "group-level" scheduling problem, that is, to determine the production sequence between PCB organization.