1. Introduction

In this laboratory exercise you will be introduced to more modeling features in Arena that are targeted at modeling production systems. As discussed in class the modeling orientation in Arena is “process orientation”. The focus when developing models is on the flow of entities in a system. In this lab you will model a system where entities of two different types are moving in a system.

You will work in teams, and use Arena simulation software to modify/enhance a model of a small electronics assembly system. You will start with an existing Arena model that will be reviewed by the instructor. This model will then be modified to make a more realistic production system model.

2. Arena

Some of the Arena modeling techniques that will be covered in this lab are:

.    Using attributes

.    Batch arrivals

.    Decision modules

.    The Expression Builder

.    Resources schedules

.    Resource failures

There is a large amount of electronic Arena documentation available in pdf files in the Rockwell software folder for more information.

3. Electronics Assembly System Model

The instructor will guide you through the initial model for the electronics   assembly system, which is shown below. The Arena model is “Electronics Assembly Model”.

Bullet points describing key system features:

.    The system produces two different sealed electronic units (A, B).

.    Part A and Part B have separate prep areas that use manual labor.

.    Both unit types go to the Sealer station for automated assembly and testing, and then to Shipping or Rework (a manual operation).

.    After Rework units are salvaged (and shipped), or scrapped.

.    Material movement times throughout the system are minimal and will be ignored in the simulation.

Part A Information:

.          Interarrivals:  expo (5) minutes

.          From arrival point, proceed immediately to Part A Prep area

o    Process = (machine + deburr + clean) ~ tria (1,4,8) minutes

.          Go immediately to Sealer

o    Process = (assemble + test) ~ tria (1,3,4) min.

o    91% pass, go to Shipped; Else go to Rework

.          Rework: (re-process + testing) ~ expo (45) min.

o    80% pass, go to Salvage/Ship; Else go to Scrap

Part B Information:

.          Interarrivals:  batches of 4, expo (30) min.

.          Upon arrival, batch separates into 4 individual parts

.          From arrival point, proceed immediately to Part B Prep area

o    Process = (machine + deburr +clean) ~ tria (3,5,10)

.          Go to Sealer

o    Process = (assemble + test) ~ weib (2.5, 5.3) min. , different from Part A, though at same station

o    91% pass, go to Shipped; Else go to Rework

.          Rework: (re-process + test) = expo (45) min.

o    80% pass, go to Salvage/Ship; Else go to Scrap

Model Run Data and Output

.          Start empty and idle, run for four 8-hour shifts (1,920 minutes)

.          Collect statistics for each work area on

o    Resource utilization

o    Number in queue

o    Time in queue

.          For each exit point (Shipped, Salvage/Shipped, Scrap), collect the total time in system.

4. Additional Modeling Features

The instructor will guide you through using two additional modeling features:

.    Schedules

.    Resource failures and repairs

Powerpoint slides will be used.

5. Lab Assignment

1.   Run the Electronics Assembly Model for a single replication with no warm-up for 160 hours (or 20 8-hour days). Examine the performance measures specified in section 3. What appears to be a problem area and why?

2.   The original model was reviewed with the production manager who pointed out that the simulation only considers the first shift of a two-shift day. On the second shift there are two operators at Rework, and the system runs  16-hours per day instead of eight hours per day.

Complete  modifications  to  the  “Electronics  Assembly  Model”  to  create  the “Enhanced Electronics Assembly Model” that incorporates the features pointed out by the production manager. Run a single replication with no warm-up for 160 hours (or 10 16-hour days). Set the base time units to minutes. Examine the performance measures. Is the problem identified in (1) still present?

3.   The  Electronics  Assembly  facility  is  considering  replacing  the  manual  prep workstations with automated machines. This will allow them to reduce their staff to just those necessary to restore machine failures (not included in the simulation).