Each part type arrives as follows.
- Part 1 arrives randomly with an average of 15 minutes between arrivals.
- Part 2 has an interarrival time that averages 17 minutes with a standard deviation of 3 minutes.
- Part 3 can arrive with an interarrival time of anywhere from 14 to 18 minutes apart.
- Part 4 arrives in batches of five almost exactly 1 hour and 10 minutes apart.