question

The direct answer to your question is to change the fill order of FlowUnit1 to Width then Length instead of Length then Width. This fixes your specific drawing issue in this specific model. However, while the drawing algorithm may happen to get the exact number of items drawn correctly, it is not guaranteed to, and we don't plan to change that. The drawing algorithm works the way it works. It doesn't track individual items, it only draws things to resemble certain densities. You can't expect it to get item quantities exactly right all the time.

The more important but indirect answer to your question is that I don't think you're building your model right. If there are a ton of green lines right next to each other running down the conveyor, then you're probably doing something wrong in your model. Each one of these lines represents a rate change point, and the conveyor must process each of these as an event every time a rate change point intersects an end of a conveyor. This is what I call chunking. Chunking effectively negates much of the advantage of using mass flow conveyors over regular conveyors, because you're constantly changing flow rates.

Chunking can easily happen when you do a discrete-to-fluid conversion. The conveyor will take the flow as fast as it can, which means that the 'item' will be depleted before the next item is available to be sent. So the conveyor must then change the rate back to zero once it's received the full amount. Then it goes back up when it gets the next item. So you're essentially sending the item down the conveyor anyway, just as a chunk of flow rate. So why did you even convert to fluid in the first place?

There are several ways to avoid chunking.

• Use the Generative Rate property on the mass flow conveyor instead of making an item-to-fluid conversion
• Batch your items together more before sending them down the conveyor. This doesn't avoid chunking, it only decreases the number of chunks. For example, you could represent an entire batch run of bottles/cans, etc. as one single flow item. If you need to produce 50,000 bottles, create a single flowitem, send it to the mass flow conveyor, and make it into 50,000 flow units. This will cause your first conveyor to completely fill up to its max flow rate. You may not want this, so you may need to...
• Send your items first to a 'throttling conveyor'. This conveyor regulates the flow rate of bottles entering the system, and subsequently sends them to the bigger conveyor. This throttling conveyor matches (or ever-so-slightly slows down) the rate of items that are being sent to it. This is the proper way of avoiding chunking when making an item-to-fluid conversion.

massflowconveyor_1.fsm