[ewilliams]

You will need (to begin with) all cycle times for the operations on the two lines, positions and sizes of all buffers on those lines (if any!), the speeds, lengths, and parts capacities of the conveyors, whether the conveyors are accumulating or non-accumulating, the arrival rate of parts to this system, information on the frequency and duration of all downtimes, considerations of logic flow (is part flow strictly upstream-to-downstream, or can parts "return upstream" (e.g., they have failed an inspection and go back for rework)), all rules of service priority (are they ever different from first-come-first-served [FCFS], schedule of operations (lunch breaks, coffee breaks, number of shifts), etc. Some things the hedging "etc." might cover are availability of labor (if some operations are manual), the methods of material handling (in addition to the conveyors, are there any forklifts or AGVs in use, etc.) There's that "etc." again! But these items will give you a good start and put you well on the road to simulation success. As a 30-year veteran of simulation, after meeting with a client to ask a series of detailed questions about the system to be simulated, I always ask, as we're about to arise from the meeting table, "What important questions have I forgotten to ask you?" That is my metaquestion -- literally, a question about questions.