ISE 403 Section: ___

In-Class Laboratory Assignment #16

Names:

1.______

2.______

Driver's Name:______

From Step 3:

The route time of three minutes is held as a Variable. What is it?
______

From Step 11:

Now under the Entity statistics, write down the flow times for:

Part 1: ______

Part 2: ______

From A:

Re-run the simulation and record the following new values:

Part 2 Cycle Time:______
Part 4 Cycle Time:______

From B:

What is the scheduled utilization for the new machine at Process C: ______

What is the schedule utilization for the old machine at Process C:

______

In-Class Laboratory Exercise #16

Driver's Name:______

Lab Purpose: To provide experience in modeling with Stations, Routes, and Sequences.

Simulation Problem: A part arrives every 10 minutes to a three-workstation cell. There are four part-types, each with an equal probability of arriving. The process plans (routing) for the four part types are given below. The entries for the process times are the mean and standard-deviation parameters for a normal distribution (in minutes).

Part Type

/ Workstation Process Time / Workstation Process Time / Workstation Process Time

Part 1

/ A
9.5, 2 / C
14.1, 2.8
Part 2 / A
13.5, 2.3 / B
15,3 / C
8.5, 2.1
Part 3 / A
12.1, 1.8 / B
9.5, 2.1
Part 4 / B
12.6, 1.7 / C
11.4, 1.4

Assume the transfer time between all stations is three minutes. Run the simulation for 5,000 minutes.

Approach: Begin by copying the partially built model InClassLab16.doe.

Step 1: The Create module causes one part to arrive every 10 minutes. In the Assign module, the part is distributed evenly among the four part types through what attribute: ______

Step 2: Four stations have been placed. What are their station names: ______, ______, ______, ______

Step 3: The route time of three minutes is held as a Variable. What is it? ______

Step 4: Add the station and process for Workstation C and the route from it.

Step 5: Process plans for Part 1 and 2 are already specified in the Sequence data module from the Advanced Transfer panel. Notice the assignment of the “process time” for each process. Now fill out the remainder of “process plan” given above. Be sure to include the Exit System station as the last step. Use the names Part 3 Process Plan, Part 4 Process Plan. Be sure to assign the attribute Process Time for each step.

Step 6: Once an entity knows its part type, it needs to “link” that part to the appropriate process plan. Use an Advanced Set from the Advanced Process panel. Notice the choices. Check the “other” category so you can press the other button for “Others…” sets. Click to “add” a set name. Add the set name “Part Sequences” – that’s the name the textbook usually uses for routings. Now you can add the members. Remember that we are creating a set of process plans, so we need to add the sequence names. It’s important that the first member of the set be the first part sequence, the second member be the second, and so forth (these are “ordered sets”). So add as the first member “Part 1 Process Plan”. The second member is “Part 2 Process Plan”. Complete that set.

Step 7: Now you need to assign in the ASSIGN module the fact that a given part type has a given process plan. Add an assignment using the “Attribute” assignment type. Note that you want to assign to the Arena-defined attribute “Entity.Sequence.” Its value would be the specific sequence as follows (if you used the recommended naming scheme):

Part Sequences (Part Index)

Step 8: Next we need to be sure that the “routes” use the part sequences. In the Route modules, change the Destination Type to “Sequential”. Do this for all the Route modules.

Step 9: Run the simulation using the “fast-forward” to be sure you haven’t any errors. Do your numbers look reasonable? My flow time for parts is around 63 minutes.

Step 10: Now we want to obtain cycle times for each part type separately. We could use a Tally set (do you know how?). Instead we will let Arena do it for us by modifying the entity “types”. Create a set of “entity types” from the Set data module in the Basic Process panel. Call the set Entity Types. Add four members “Part 1”, “Part 2”, etc. In the Assign module, assign the Arena-defined attribute “Entity.Type” the value of
Entity Types(Part Index)

Step 11: Run the simulation using the “go” and the “fast-forward” to be sure you haven’t any errors. Now under the Entity statistics, write down the flow times for:

Part 1: ______

Part 2: ______

Part 3: ______

Part 4: ______

Embellishments:

Consider the following embellishments:

A.Use the Expressions feature to determine the processing time for Workstation B. Using the Expression module from the Advance Process panel, define an expression, say “WSBProcessTime”, having four rows (one row for each part type). Make the four values of the expression correspond to the four processing times – the first is 0, the second is Normal(15,3), and so forth. Now change the Process Time in Workstation B to WSBProcessTime(Part Index).

Why is 0 used for the first initial value? Could it have been 15?
______

______

Re-run the simulation and record the following new values:

Part 1 Cycle Time:______
Part 2 Cycle Time:______
Part 3 Cycle Time:______
Part 4 Cycle Time:______

B.A new machine for Process C is being considered that is 25 percent faster. We would keep the old machine and use it when the newer one is busy. To implement this, you need a resource set for machines at Process C. Since we prefer the use of faster machine, use Preferred Rule. Also, save the index of the seized machine in an attribute, e.g. “machine index”. To adjust the process time for associated “efficiency”, use a variable (with 2 rows) to store machine “efficiency.” Use this variable and “machine index” when computing the process time at Process C.

Re-run the simulation:

What is the scheduled utilization for the new machine at Process C: ______

What is the schedule utilization for the old machine at Process C:

______

C.We want the Transfer time between Workstation B and Workstation C to depend on the part type. Part type 2 takes 2 minutes while Part type 4 takes 4 minutes. Write an Arena expression that you can place into the Route Time specification. Remember that (Part Index == 1) has a value of 0 if false and 1 if true.

______

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