Scenario Description
A shop floor is the area in a manufacturing facility where production is carried out, by machines and
operators. In this scenario, a shop floor consists of 3 production sections, each section has 2 operations is
considered. These operations are repeated/similar across all sections, so that arrived jobs can be
processed at any section. Jobs frequently arrive at irregular/random intervals and can select any of the
sections based on the queue size (least).
The job shop manufacturing system encountered many scheduling problems. These problems include
variations in batch sizes, processing times, inventory levels, work in progress (WIP), performance, etc.
The following description shows the flow of operations in this shop floor.
• The inter-arrival times of jobs (in minutes) follow a user-defined distribution based on
Exponential with an Average equal to 10.
• The shop floor consists of 3 production sections (Section 1, Section 2, and Section 3). See Figure
1 for the shop floor layout.
Figure 1: schematic diagram of the shop floor
• Upon arrival, the job selects a production section based on the shortest queue size.
• Each section has two operations, these operations are repeated across all sections. See Table 1
for the shop floor operations.
Table 1: Shop floor operations
SECTION
NUMBER
OPERATION
1 Operation 1 and 2
2 Operation 1 and 2
3 Operation 1 and 2
• Two machines are used at each section. These machines are similar across all sections. Although
these machines are similar, each production section has its own (not shared) machines. See Table
2 for further information about the used machines.
Table 2: Machines used in each section
SECTION
NUMBER
OPERATION
1
OPERATION
2
1 M1-1 M2-1
2 M1-2 M2-2
3 M1-3 M2-3
- M1-1 refers to machine 1, section 1 location
• Four skilled operators are working in the shop floor, some of these operates can operate more
than one machine (multi-skills). Each machine requires only 1 operator allocated with the
related skill. See Table 3 for skills of operators.
Table 3: Skills of operators
OPERATION
1
MACHINE 1
OPERATION
2
MACHINE 2
JOHN
MIKE
JIM
FRED
JIM
MIKE - 1 Machine requires only 1 operator
• Each section has different efficiency in terms of operational/process time. This depends on the
allocated operator’s performance (represented here by random expressions). See Table 4 for
section/operation process times.
Table 4: Process times of each shop (in minutes)
SECTION
NUMBER
OPERATION 1 OPERATION 2
1 UNIF( 10 , 20 ) 25
2 35 TRIA( 22 , 35 , 43 )
3 50 60
• Only one job can be processed at a time.
• The service discipline follows the First-In-First-Out rule.
Increasing productivity is the first industry priority and this leads to using sophisticated technologies that
have changed the outlook of the shop floor. One of these technologies is computer simulation that is used
to imitate the shop floor operations for best performance of resources including operators and machines.
Coursework Tasks
For this piece of individual coursework, you are required to apply simulation modelling to
deliver the tasks below:
Task 1- After reading the scenario above, provide problem brief, main aim, objectives, tools and
techniques, and key performance indicators.
Task 2- Use tabular form to define and analyse the Shop Floor Scheduling problem. This analysis
includes decomposing the system being investigated into its main components including entities,
attributes, activities, state variables, and events.
Task 3- An appropriate flowchart with detailed explanations.
Task 4- An appropriate Activity Cycle Diagram (ACD) with detailed explanations.
Task 5- Develop a business simulation model for 200 jobs to imitate the above scheduling problem
(“As-Is” situation) in order to increase productivity of the shop floor operations. Five simulation runs are
required, at least two experiments (scenarios) to achieve a reasonable:
i. Overall simulation time.
ii. Queue size at each.
iii. Average waiting time.
iv. Resource(s)/ service facility(s) utilisations.
A comparison via Excel diagrams of the “As-Is” scenario with any other improvement scenarios “WhatIf” is required.
Task 6- Conclusion and Recommendations for further improvement (bullet points)
Sample Solution
