# Manufacturing

- Conveyor belt (Conveyor):
- special stock element introduced in Stella,
redesigned in Modelica
- functionality
- operates at clock ticks t
_{n} = t_{0}
+ n Δt
- stores input value
- outputs the value after a given transit time t
_{tr}

- example
- inflow = 5 (per time unit)
- t
_{0} = 0.1, Δt = 1, t_{tr} = 3

- results
- details
- discrete simulation at sample times t
_{n}
= 0.1 + n
- needs discrete stock component StockD
- input flow is 5 for 2.5 ≤ t ≤ 13 (implemented
with TimeSwitchedConverter)
- initial waiting time < Δt is rounded to Δt

- Manufacturing machine (Oven):
- another discrete stock from Stella
- baking tray model: fill tray, bake, unload
- parameters initialLoad, capacity, cookingTime
- processing phases
- loading: get input, until capacity is reached
- production: wait until cookingtime
ends
- unloading: output complete content, immediately
start with reloading

- example with initialLoad = 0,
capacity = 3, cookingTime
= 2
- results

- Model of a simple assembly line:
- delivery of 2 units per time unit of raw material
- stored in inputStore with
initial stock = 7
- path2 transports 2 parts per
time unit
- machine1 has a capacity of 4
and needs 2 time units
- conveyor12 has a transport
time of 2 time units
- intermediateStore for
buffering, initially empty
- path5 transports 2 parts per
time unit
- machine2 has a capacity of 2
and needs 1 time unit
- outputStore for final
products, initially empty

- Simulation results of model AssemblyLine:
- expectation: throughput of 2 parts per time unit
- inventory of the stores
- problem
- inputStore grows
continually
- uneven growth of outputStore
- average throughput: 1.5 parts per time unit
- all stations allow for a throughput of 2 parts
per time unit

- cause
- behavior at machine1
- path2 transports 2 parts
per time unit
- can't deliver during production time of machine1
- loading of machine1
needs 4 parts, but only 2 parts can be delivered in one step

- solution:
- path2 must be extended
to transport 4 parts per time unit
- simulation shows necessary sizes of stores under
optimal conditions