Modelling a Hybrid Flow Shop using OntoGui

Case Description

The flow shop is composed of 5 machines and 5 buffers which are connected accordingly

The processing time of each machine varies according to the part(classes).

process times

Each of the machines has failure modes with different mean time to repair and mean time to failure. M1, M4, M5 have two failure modes and M2,M3 have only one failure mode.

failure modes

Formal model

formal model

Modelling of Hybrid Flow shop (Using OntoGui)

Control panel

control panel

1. A new ontology module Hybrid Flow-shop has been created.

2. System design tool is selected under the ontology tools.

System Design

System Design window is opened

Part Types

part a part types

1. A new part called Part-A of the class Workpiece type is created

Process Plans

part a process plan

1. A process plan prodplan is created for the Part-A

Process Steps

part a process step M1.1

part a settime M1.1

1. M1.1 is the process step of the machine M1. The processing time of 1.1s is entered using the set time option and Manufacturing task is selected under the set class option.

2. M2.1 is the process step of the machine M2 with a processing time of 0.9s

3. M4.1 is the process step of the machine M4 with a processing time of 1.5s

4. M5.1 is the process step of the machine M5 with a processing time of 0.7s

Successors of process step

part a successor M1.1

1. M2.1 is selected as a successor of M1.1 using the add button under add successor. M3.1 is the successor of M2.1 and M4.1 is the successor of M3.1.

Systems

system create

1. A system called Hybrid flowshop of the class Manufacturing system is created.

system add B1

1. The machines M1,M2,M3 and M4 and buffers B1,B2,B3 and B4 are created under this system using the Add new option.

Managing connections of selected machine

1. For M1, B1 is in upstream and B2,B3 are in downstream. For M2, B2 is in upstream and B4 is in downstream. For M3, B3 is in upstream and B4 is in downstream. For M4, B4 is in upstream and B5 is in downstream. For M5, B5 is in upstream and B1 is in downstream.

Manage properties of Buffer

system buffer capacity B1

1. The buffer capacity of each buffer was entered in the box.

Manage failure modes of machine

system failure mode M1

1. The failure mode properties of each machine are entered. The failure type is "ODF". Time to fail is recorded in terms of hour and time to repair is in terms of minutes. The value is entered in properties value dialog box.

2. The procedure is repeated for all the other machines as well. M1 and M4 have two failure modes

3. The value can be modified later by using the set button

Assignments of process step

part a assignM M1.1

1. The machines are assigned to respective process step. M1 is assigned to M1.1, M2 is assigned to M2.1, M4 is assigned to M4.1 and M5 is assigned to M5.1.

Part Types

part b part type

1. A new part called Part-B of the class Workpiece type is created

Process Plans

part b process plan

1. A process plan prodplan.1 is created for the Part-B

Process Steps

part b process step

1. M1.2 is the process step of the machine M1. The processing time of 1.3s is entered using the set time option and Manufacturing task is selected under the set class option.

2. M3.2 is the process step of the machine M3 with a processing time of 2.1s

3. M4.2 is the process step of the machine M4 with a processing time of 1.2s

4. M5.2 is the process step of the machine M5 with a processing time of 0.8s

Successors of process step

1. M3.2 is selected as a successor of M1.2 using the add button under add successor. M4.2 is the successor of M3.2 and M5.2 is the successor of M4.2.

Assignments of process step

1. The machines are assigned to respective process step. M1 is assigned to M1.2, M3 is assigned to M3.2, M4 is assigned to M4.2 and M5 is assigned to M5.2.

Part Types

part c part type

1. A new part called Part-C of the class Workpiece type is created

Process Plans

part c process plan

1. A process plan prodplan.2 is created for the Part-C

Process Steps

part c process step

1. M1.3 is the process step of the machine M1. The processing time of 1s is entered using the set time option and Manufacturing task is selected under the set class option.

2. M2.3 is the process step of the machine M2 with a processing time of 1.1s

3. M4.3 is the process step of the machine M4 with a processing time of 0.7s

4. M5.3 is the process step of the machine M5 with a processing time of 0.5s

Successors of process step

1. M2.3 is selected as a successor of M1.3 using the add button under add successor. M3.3 is the successor of M2.3 and M4.3 is the successor of M3.3.

Assignments of process step

1. The machines are assigned to respective process step. M1 is assigned to M1.3, M2 is assigned to M2.3, M4 is assigned to M4.3 and M5 is assigned to M5.3.