Question

You are a supplier of printed circuit boards (PCBs). Production of the circuit boards consists of several steps – Surface Mounting, Baking, and Final Assembly. Surface Mounting puts integrated circuits (ICs) and other components on a PCB. These PCBs are then Baked as a batch and kept in an oven for some time so that the ICs are soldered onto the PCBs. Finally, these PCBs are taken and manually assembled into a case, and wired with connectors. The processing rate at the Surface Mounting station is 15 PCBs/minute, the processing rate for Baking is 5 PCBs/minute, and the processing rate for Final Assembly is 3 PCBs/minute. If there are on average 24 units of (work in process) inventory and the system is working at capacity, what is the flow (throughput) time for PCBs?

Answer 1

the flow (throughput) time for PCBs is 40 units per minute

Step-by-step explanation:

Given that;

Work in progress WIP = 24

we calculate the time spent to make the PCBs, lead time

Processing rate at the Surface Mounting station is 15 PCBs/minute

so time taken by a single PCB at the SM operation = 1/15 min

Processing rate for Baking is 5 PCBs/minute

so time taken by a single PCB at the baking operation = 1/5 min

the processing rate for Final Assembly is 3 PCBs/minute

so time taken by a single PCB at the assembly = 1/3 min

∴ total time taken will be;

(1/15) + (1/5) + (1/3)

= 0.6 min

Now, using Little's Law;

Working in progress WIP = throughput × lead time

Throughput = WIP / Lead time

so we substitute

Throughput = 24 / 0.6 min

Throughput = 40 units per minute

Therefore the flow (throughput) time for PCBs is 40 units per minute