SIMULATION OF VOLVO BUSES, INDIA Present &...

SIMULATION OF VOLVO BUSES, INDIA

Present & Future

KPP319 INDUSTRIAL EXCELLENCE

Authors

Harishkumar Rajuvadan Premkumar Hariram Vedapatti Ranganathan

Jayaprakash Lakshmikanthan Nandakumar Ranganathan

School of Innovation, Design and Engineering – IDT

Mälardalen University, Eskilstuna, Sweden

KPP319 Industrial Excellence Group 6

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Abstract ”Simulation of VOLVO Buses, India – Present & Future” project mainly focusses to improve

the real industrial process through the simulation by using the knowledge gained. ExtendSIM

and 3D CREATE are used which are simulation tools to test the dynamicity of the model. We

took VOLVO Buses Factory, India as our case company to analyse the current state of

processes and project a visualization perspective of future state after improvements. Initially

we started with building a model for the current state of the processes to find and show the

problem scope. Here we modelled the major processes performed in the assembly line. In

addition we have shown the customization attributes which has dynamics towards customer

specifications. After the model is validated, the problem is focussed using the theoretical

knowledge gained in the program, to provide solutions for the Improvements which answers

”How will the factory and process look after the implementation of the Improvements?” in a

3 dimensional visualized simulation process using 3D Create.


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About the Company VOLVO BUSES INDIA, the factory was established in the year

2007. The factory was constructed with a capacity to produce 1000 buses/year. The

company’s corporate value is Quality, Safety and Environmental Care. At present the

company produces two types of buses namely CITY and INTERCITY buses.

The company has a factory expansion plan in order to cater the

market demands. Their operative vision in 2015 is to produce 5000 buses with lesser

throughput time, Produced in reduced cycle time, with bench mark in quality, by setting

standards in productivity and nurturing the culture, focussed on people development.

VOLVO INTERCITY BUS 9400 VOLVO CITY BUS 8400


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Contents

INTRODUCTION ................................................................................................................................................................... 7

BACKGROUND AND DESCRIPTION OF SIMULATION CASE..................................................................................................................... 7

OBJECTIVES AND GOALS ........................................................................................................................................................................... 8

PROJECT PLAN ........................................................................................................................................................................................... 9

EXPECTED RESULTS............................................................................................................................................................................... 10

THEORETICAL BACKGROUND ..................................................................................................................................... 13

SIMULATION AS A TOOL WITHIN PRODUCTION AND LOGISITCS MANAGEMENT: .......................................................................... 13

DISCRETE EVENT SIMULATION ........................................................................................................................................................... 14

PURPOSE OF SIMULATION .................................................................................................................................................................... 15

3D MODELING ........................................................................................................................................................................................ 17

PROCESS DESCRIPTION ................................................................................................................................................. 20

PROBLEM AND REASON FOR SIMULATION ......................................................................................................................................... 20

GENERAL LAYOUT OF THE COMPANY .................................................................................................................................................. 21

PROCESS FLOW CHART.......................................................................................................................................................................... 22

OVERVIEW OF STATIONS 1 TO 8 ......................................................................................................................................................... 22

DATA COLLECTION ................................................................................................................................................................................ 23

MODEL .................................................................................................................................................................................. 25

SIMULATION MODEL CONSTRUCTION................................................................................................................................................ 25

LOGICAL MODEL DESCRIPTION ........................................................................................................................................................... 27

3D MODEL DESCRIPTION ...................................................................................................................................................................... 27

VALIDITY AND RELEVANCE OF THE MODEL ....................................................................................................................................... 28

SIMULATION ...................................................................................................................................................................... 31

RESULTS FROM SIMULATION ............................................................................................................................................................... 31

RESULTS AND CONCLUSIONS ....................................................................................................................................... 34

ACKNOWLEDGEMENT .................................................................................................................................................... 35

REFERENCES ...................................................................................................................................................................... 35


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APPENDIX ........................................................................................................................................................................... 36

3D MODEL – FIGURE ............................................................................................................................................................................ 36

EXTENDSIM MODEL ....................................................................................................................................................................... 40


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CHAPTER 1


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INTRODUCTION

BACKGROUND AND DESCRIPTION OF SIMULATION CASE

This project is about learning the simulation software’s ExtendSim7.0 and 3d Create. For this

aim, we are going to work with Volvo Buses India, with the focus point of showing the entire

station work carried from Station 1 to 8 using ExtendSim, which shows the reason for the bus to

proceed to yard. In 3d Create software the future model of the factory is visualized between

stations 1 to 4. Knowledge form previous courses and previous experience is used in this project

to achieve the goal. The project team has a common goal to complete the assigned project more

successfully, and learn as much as we can!

PROJECT ORGANIZATION

The project group is well organized by group contract, signed by all group members. Each and

every member is given responsibilities for a specific task to be done.

Company VOLVO BUSES INDIA

Project Leader Harishkumar Rajuvadan Premkumar

Secretary Hariram Vedapatti Ranganathan

Report, Documentation,

Presentation

Jayaprakash Lakshmikanthan

Nandakumar Ranganathan

Project Group Members

Persons Performing the Study

Harishkumar Rajuvadan Premkumar

Hariram Vedapatti Ranganathan

Jayaprakash Lakshmikanthan

Nandakumar Ranganathan


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Support Group

Vasanth Raj Yuvaraj

Alfred Maria Joseph

Sifei Zhang

Azeem Syed Muhammad Waqar

Shah Bilal Ahmed

Steering Committee

Steering Committee

Mats Jackson

Magnus Wiktorsson

OBJECTIVES AND GOALS

To learn the simulation software – EXTENDSIM 7.0 and 3d Create Software

To stimulate a part of a VOLVO Buses factory Station 1 to 8 (Using ExtendSim)

- To find out the reasons for proceeding to Yard, in terms of

Customer order priority

Payment Issues

Incomplete work in previous stations.

- Customer preference in customization in between stations is also shown

between stations 1 to 8.

To stimulate the future model of a VOLVO Buses factory Station 1 to 4 (Using 3d Create)

- Improvement with less labour force (balanced machine and labour force)

- On time Completion

- Warehouse, providing a mini storage area for handling dismantled parts at

Station 4.


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PROJECT PLAN

The project follows the DMAIC – model (Define, Measure, Analyze, Improve and Control). The

time plan is planned after this model and first deadline includes define. Here is the problem

description and expected result specified. We are also setting up our time plan in this part. Next

gate, P2, is the measure part. Here is all information is collected and software learning is done.

The information is analyzed and ExtendSim model is done in the third gate, P3, and in the fourth,

P4 - 3d Modelling is done. In the last phase, P5, we present our future suggestions. Improvement

and Control will not be discussed in this study.

Week 38. Deadline 2011-09-23 (P1) Project Specification

Description of the problems and objective formulation

Project Organization

Time Plan and Deliverables

Delimitations

Expected Results

Week 41. Deadline 2011-10-11 (P2) Process Description

Data Gathering

Defining Process

Learning the software

Model Construction

ExtendSIM

Modelling

P3 Process

Description

P2 Project

Specification

P1

3D CREATE

Modelling

P4

Presentation

P5

Define Measure Analyze Improve

Control


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Week 44. Deadline 2011-11-01 (P3) Simulation Modelling (Extend SIM)

Final Extend SIM Model

Verification and validation

Week 46. Deadline 2011-11-15 (P4) Simulation Modelling (3D CREATE)

Learning Software in Detail

Analyzing the scope for improvement

Verification and validation

Week 48. Deadline 2011-12-06 (P5) Presentation

Report Preparation

Recommendation for further improvements

Delimitations

The project is concerned with bus body building, since numerous activities are involved during

the process of bus building. For our project, only the main activities in all stations alone are

considered. In Extend SIM we simulated stations 1 to 8 and stations 1 to 4 in 3D CREATE (future

state) as a holistic view, since it is not possible to show the entire process. Also it is assumed that

the materials come from the substations and warehouses in time. A prebuilt bus model is shown

in 3DCREATE instead of the bus model without a body, since such model is unavailable. Also, the

robotic actions of welding are only to show that welding process takes place and not the welding

process procedures.

EXPECTED RESULTS

Student aspect

Knowledge and capability to work in Extend SIM and 3D CREATE software through a case

company and to model real industrial production process. Applying knowledge to improve the

industrial process / project a scope for improvement.


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Company aspect

Analysis of current state processes using Extend SIM: real time process flow along with their

attributes and validate it. Visualize the future state using 3D CREATE.


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CHAPTER 2


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THEORETICAL BACKGROUND

SIMULATION AS A TOOL WITHIN PRODUCTION AND LOGISTICS MANAGEMENT: Simulation is a tool used for building up a model that describes detailed

information about the real situation. The result obtained from the simulation can be used to

analyze the system over different operating conditions. Its is the standard tool to design, model

the different type of manufacturing industry. It is very helful for building up of process

production and logistics with in the company. It can be modify and conditions can be applied at

start and end of the events within a system.

Many industrial manufacturers mainly focus on the efficient production based on the cost and

quality of the product. The manufacturers face many problems and difficulties to meet the

market demands like wider product variety, quick delivery, high quality, customization, cost

reduction etc., Simulation is very useful to solve these problems and helps to build a new model

and layout of the company to meet these demands. A new production flow line can be visualized

with the help of simulation, based on variety of products.

There are several techniques associated with simulation used to address variety of problems

based on the applications. Here we list out three techniques, they are

Enterprise Resource Planning and Product Lifecycle Management:

A process carried by company manages and integrates the main parts of its

business. An ERP management information system integrates department such as purchasing,

planning, sales, marketing, finance, human resource etc., the concept of enterprise resource

planning, and the systems designed to supply the functionality required to make the concept a

reality, represent a significant step in the long history of technology assisted business process

integration. In ERP system, each department will have their own system to optimize for their

particular tasks concern in their each department and also they can communicate each other

and also share their information easier with the rest of the company.

Product cycle management representing the vision for managing all the department and data

related to design, production, support and ultimate disposal of manufacturing goods. All the

products that are produced have certain life cycles. This life cycles describes about the products

from the raw material to the finished goods till it delivery to the customer. The understanding of

the product life cycles helps the company to understand the market demand and when the

product can be produced and when product can be launched in the market.

Optimization

Simulation optimization is defined as process of finding the best input parameter

values among the other all possible available parameters. The main aim of the simulation

optimization is to minimize the resource by maximize the information obtained from the


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simulation results. There are about six main categories of simulation optimization methods. In

this concern, many of the methods need speed judgment of the output parameters value at a

given parameter vector value. The six methods are,

1. Gradient based search methods

2. Stochastic optimization

3. Response surface methodology (RSM)

4. Heuristic methods

5. A-teams

6. Statistical methods.

Web Based Simulation

In global, there is a development of using web as a new platform for applications.

Hence the simulation community people have been forced to switch to the web for multiple

advantages reasons. This web based simulation particularly focused on end users and

collaboration. Web based simulation is concerned about two main views; both view is based on

java language. One is based on designing the model using java language and another is about

approach ports an existing simulation language, (i.e.) GPSS and creates in java. The advances in

java development tools that can allow to use the reusable components in combination with

ability to create model and execute model through internet faster. The main purpose to use web

based simulation are,

1. The simulation model done by the java can be made widely available.

2. Any model can be regain and execute in any platform. Even it is unnecessary to

recompiled or delinked.

3. This can be easier to implement the simulation with respect to the real system.

4. Web based simulation also supports for different animations to make the model better

understand.

5. It is small, safe, clean and easier to use than other program.

6. It can be easily accessible from any part of the world and it can be corrected faster than

the other one.

7. It also improves the quality of simulation model as respect to the needed application.

DISCRETE EVENT SIMULATION Discrete event simulation, It is the cyclic process and sequence of events in

operation of the system. It consists of several numbers of events, which occur in particular time

and results in change of state. In a system, group of an object that coexists and interrelate

towards the accomplishment of some purpose. Systems exist within an external environment is

called system environment.

The important part to be considered in simulation is developing a model of the

structure. To develop such system, the following parameters are to be considered, they are

Objects: It helps to build the structure of the system.


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Rules: There are various rules and conditions to be considered. This helps how to

interact the objects with one another.

Inputs: To build a system, various inputs are needed to make the structure of the system

objects.

Activities: It represents several actions takes place in some time period of particular

length.

Delays: Delay is the time gap between the start and end of the particular activity. It also

not allowed performing the desired activity if there are no material resources.

Event : It is a process takes place immediately which results in changes of state of the

system, there are two types of event, they are

1. Endogenous: events takes place within the system

2. Exogenous: event takes place outside the system or in the closed system

environment.

Purpose of simulation The various purpose of simulation is as follows,

Simulation is more cost effective when compared to other methods and real testing.

1. It is very to model the simulation system.

2. It also provides more flexibility. The parameters can be change easily and evaluations of

parameters are easily done.

3. It provides an enhanced understanding of the system.

4. It is used to judge the system behaviour in closed environment. This helps to make effect

of changes in parameters.

5. It is impossible to observe the real system, hence simulation helps to analyse and make

decision before implementation of the real one.

6. It gives better solution for modelling and analyse the situation.

Cases to avoid the stimulation

There are several cases, in which simulation should be avoided for better results,

The conditions upon simulation are,

1. The problem which can be addressed analytically or using common sense.

2. The problem can be solved directly by using the direct experimentation.

3. The cost for making simulation which exceeds more than the expectation.

4. The various parameters which are not available like time, money or important data to

model the simulation.

5. If the system is too complex and difficult to understand.

6. Lack of knowledge to verify and validating the simulation model.


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Steps to be followed to develop the simulation model:

To develop a simulator for process planning may consist of the following steps,

1. Recognition of a problem: In this step, first we must find the exact problems that are faced in the industry. We must list all the problems and even we must identify the hidden problems. These problems should be ranked based on the cause. They should be prioritized from high to low.

2. Delineation of the system to be studied: The delineation of the system should be done based on the problems that are collected earlier. Each problem should be studied in depth and they should find the root cause for these problems and also they should find the approximate solution which affects the system in better way. Now, these problems should be prioritized based on their solutions.

3. Formulation of questions to be asked: A series set of questions can be raised, while collecting and studying the problems. The set of questions should be formed. These questions should be asked to the labour, which is responsible and expert in that department. After collecting this information it help to improve your case study on those problems and make clear view to your ideas for modelling the simulation.

4. Gathering of information to create model: After finishing your case study on problems, now we must collect the information need to develop the model. Collecting several data for a particular work station or process like cycle time, tack time, no of employees, material flow, machining time etc. it should be collected for each work station or each process which helps in building up the simulation model.

5. Generation of the model (modelling): The Collection of these data is used to build a model for whole process. Each process should be built one by one based on the data collected. And mainly we have focus on the process which has more problems and they should be taken more care. Even simulator can focus on the particular process for improving the efficient in that particular process.

6. Running the model (simulation): Once the model is created, running the model should be done. They should compare the results and activity happen in the simulation should be compared with the real time process. The improvements should be noted for the each process. Then finally, efficiency should be calculated for the whole process and it should be compared with the old efficiency value.

7. Analysis of the results and their implications: The results from the simulation model should be studied carefully and we should list out all the possible changes can be done in the real time process. We can’t implement all the changes done in simulation. Only the certain changes can be done which gives more efficient and it should be tried with different conditions and parameters. Finally changes can be done in real time process from the results obtained from the simulation model.

The step which is more important to be focused for a successful project is finding the problem and analysis of the results and their implications.


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1. Finding the best problem is more important, because it changes the high efficiency on the whole. It’s not so important to do changes in all problems which increase the efficiency in little. So finding the best problem and giving solution to that is a better way to optimize and increase the process efficiency.

2. Next most important is analysis of the results and their implications. After getting the results from the simulation, analysis should be done in better way. And implication of these simulations in real time process is very important. Hence decision should be done correctly for the better results.

3D MODELLING

3d modelling is the computer aided design (CAD) process which helps to creation

and visualize the situation in the form of 3D objects. These can be drawn to any form we need,

even in the fantastic forms which can’t exist in the real world. The 3d modelling system comes

with the speed and creativity that designer can perform various fields like model complex, easy

to build multiple design variation, quick clean up, adapt and easy techniques.

The five steps are been followed to start with 3D modelling, they are,

1. Preparation: To start up with the 3d modelling, the designer needs to imagine and

visualize the basic needs for the project and collect relevant information. These

information can be collected from customer or employee in which designer can prepare

what he needs for the project.

2. Reference images: In this stage, he has to take out the sketches and scan the images what

he need for the projects. But commonly used objects will be available in all the software’s

based on their applications. These scanned images are imported to software if it’s not

available in default.

3. Initial modelling: After collecting all the information and data, designer used to model

from the base of the situation. Several objects are placed according to his project and

data’s are defined to each event. These 3d modelling is done by using various techniques.

4. Improvement of the model: Once the basic structure is designed, improvements are done

in each stage. This tends to adjust some objects and events so that it can work and

address the better solution.

5. Smoothing: Smoothing is the important task to be consider in 3D modelling. It helps to

make of organic models. In all 3D software, this smoothing will be available but it may be

also in different name based on the software. This helps to enhance the view and

provides natural look to the model.

Advantages of 3D modelling

There is several numbers of advantages by using 3D modelling in many industries,

they are,

1. It is very helpful for achieving great efficiency in reducing costs and lead times.

2. It helps in improving the design quality than the 2D.


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3. The errors like component collisions, incorrect quantities or unfit parts are eliminated

by using 3d modelling.

4. It helps in minimizing the rework of the design.

5. It saves more design time on complex design by using productivity tool.

6. It gives better solution on design ideas due to complete visualized capabilities.

List of 3d modelling software’s available

There are number of 3d modelling software’s available in the market based on

different applications and situations, many software developers have developed 3d modelling

software’s in the market, here we list out some examples of 3d modelling software’s, they are,

1. 3D Create

2. ExtendSIM.

3. 3d Max (Autodesk)

4. Animation.

5. Cobalt.

6. Light wave 3d (Newtek)

7. Maya (Autodesk)

8. Solid Edge (Siemens PLM software)

9. Solid works (Solid works Corporation)

10. GMax.

11. Light wave 3d.


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CHAPTER 3


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PROCESS DESCRIPTION

PROBLEM AND REASON FOR SIMULATION VOLVO Buses India, a bus body building factory – has more improvement factors since the

company established in 2007. Continuous improvement phase are taking place regularly.

Totally there are 22 stations in the factory, out of which we have simulated stations 1 – 8 (in

Extend SIM), after which it proceeds either to station 9 or the yard (For various reasons). There

are various customization process done in-between based on customer orders. We have

simulated to find how many busses proceed to Station 9 and to the yard. Three factors are

discussed 1) Incomplete work in stations, 2) Customer order priority, 3) Payment issues.

The above said factors are explained below,

Incomplete work in stations: Bus building currently involving only labour force,

the company fixed a tact time of 4 hours in each stations. Most often the work remains

incomplete in stations. After 4 hours the bus is moved to the next station even it is unfinished.

Also when the required materials for the stations do not arrive on time, the station work cannot

be completed.

Customer order priority: The priority is set according to the customer demands. If

the customer needs are more urgent, the specific bus is assigned with a high priority and the

normal priority buses in the next stations proceed to the yard paying way to the higher priority

bus.

Payment Issues: At the time of booking, the customer has to pay a certain

percentage, then once the bus is inducted in production line, the customers are intimated then

before proceeding to station 9 they have to pay quarter price of the bus. When this is not done,

the bus is moved to yard.

When a bus proceeds to yard instead of station 9 means then the company will face high

inventory cost, extra cost for labour, delivery time will be considerably increased, more

possibility for material damage.

In 3d create model – since the above said problems cannot be shown fully, we have limited to

show stations 1 to 4 with a future scope of employing both labour force and robotic force in

station 2 and station 3 for welding purpose. And also in Station 1 dismantled parts are sent

directly to station 4 by having storage near the station to handle dismantled parts alone instead

of going to warehouse and bring to station 4 at the desired time.


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GENERAL LAYOUT OF THE COMPANY

FIGURE 1 – GENERAL LAYOUT OF THE COMPANY

The figure above shows the general layout of the company. There are 22 stations involved in

production of a complete bus. Station 1 to 8 is being called as assembly line, while station 9 to 16

is being called as finishing line. Stations remaining from 17 to 22 involves in water leak test,

quality test, on road test, PDI – pre delivery inspection etc. Those are not shown in this general

layout.


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PROCESS FLOW CHART

FIGURE 2 – PROCESS FLOW CHART

The above flowchart represents the process flow algorithm of stations 1 to 8 which is encircled

in the general layout diagram. In this flow chart the main activities are visualized which stands

as a base structure for the simulation model.

OVERVIEW OF STATIONS 1 TO 8

In the company there are 22 stations, each and every station has a dedicated work

to do for the completion of the bus. All stations work with a standard Takt time of 4 hours. Based

on the customer order Chassis are inducted. According to customer order customization tasks

are carried out in dedicated stations.

At Station 1, involves inspection of the chassis and then followed by dismantling of the chassis

parts. The dismantled parts are sent to chassis reassembly station. After dismantling is done,

welding preparation is carried out. At Station 2, cross member assembly and floor preparation &

welding is done. The station receives the parts for assembly from its dedicated sub-assembly


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station. The sub-assembly station supplies the parts before 30 minutes of production start in

work stations. At Station 3, side, rear, front wall positioning and welding is done. In this station

customization task is involved, for bus driver side door. According to customer needs,

customization task is done. At Station 4, mainly involves with chassis reassembly and some roof

works are carried out. At station 5, roof is assembled fully; roof is received from its Sub assembly

station. After that customization tasks according to customer order are carried out, like fixing

chemical toilet, pantry, document box etc.

At Station 6, primer application is done. At Station 7, electrical, hydraulic, pneumatic

connections are given and also preparation starts for plywood setting. At station 8, involves fully

with plywood fitment.

After Station 8 it proceeds either to station 9 or to Yard. The reasons for going to Yard are

mainly due to customer order priority, Payment issues, Incomplete works in previous stations.

When the bus is moved to Yard, the company faces high inventory cost problems and have to

deploy additional workers to finish the incomplete work.

DATA COLLECTION The data collection is based on Internship done at this company during June to July 2011 by two

students in this group. The collected data are not given in this report.


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CHAPTER 4


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MODEL

SIMULATION MODEL CONSTRUCTION The ExtendSim Model is briefed,

The Simulation process starts with “Create” where the Induction of the bus takes

place. It is assumed that the induction takes place every 4 hours and this whole process repeats

every 40 hours. After induction, it is moved through conveyor in Guidelines from station 1 to

station 5. After station 1, Chassis is dismantled and the stream is split in to two by “unbatch” and

“DE output” where in the dismantled parts are sent to Station 4 in a FIFO queue. On the other

hand the Chassis alone proceeds to welding preparation and then to station2.

After Station 2 the chassis and the parts from the subassembly station are combined together

and move to Cross member assembly, then to Floor preparation & welding. Before entering

station 3, Customization process takes place. A Random Number is generated from 1 to 4 and

then in the Set 4 different customizations like Standard Bus, Custom1, Custom 2, Both Custom 1

&2 which are given different probabilities based on the Current demand. The numbers of each

type is counted using “Select item out, count and Select item in”. In station 3, the beam assembly

is carried out, and then combined with the parts from Subassembly 2 which is sent to Side wall

positioning & welding, Rear & front wall welding. The dismantled parts and the chassis from

station3 are combined together using DE Input & Batch (Variable) and moved to station 4 where

the chassis reassembly takes place.


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FIGURE 3 – EXTEND SIM MODEL

(Detailed Model is Shown in Appendix)

Following this, the reassembled chassis is combined with the parts from subassembly 3 through

discrete event Batch Process, Where both are required to move to the Roof Fitting (Front &

Rear). In station 5 through the conveyor, and again Batched with the Subassembly 4 parts,

where the Roof Panel assembly takes place after that.

Continuing this, the Customization is done which is for Chemical Toilet, Pantry, Document box,

Toolbox & Inner mudguard etc… based on the customer requirements. They are then counted

for their individual quantities for various types. The 4 major customizations are considered in

this case.

Primer application is carried out after the customization which happens in station 6. Proceeding

further, Electrical, Hydraulic & Pneumatic connections are made after which Ply word work is


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carried out and based on the customization, Ply wood setting by receiving parts from

subassembly5 and Station 8.

Now the bus moves either to Station9 or the yard, the reasons for proceeding to yard are,

Incomplete: If there are any quality issues or incomplete work carried out in any station 1 to 8,

they have to be fixed before going to station 9, which is done in the yard.

Payment Issues: According the company norms, it is certain that the customer should have paid

certain % amount else for which the bus goes to yard and will proceed to station 9 after

receiving the payment.

Bus Priority: Urgent orders are given more priority than the normal one.

With the past data for the probabilities for the reasons to occur, the output is split

and the count is made on the number of buses reaching the yard for above said reason and the

buses proceeding to station 9.

LOGICAL MODEL DESCRIPTION

The basic logic behind our model is that, a bus chassis which is dismantled in the

1st station followed by various processes for body building (Welding, Assembly, etc.,) in the

assembly line till station 8. There is various customizing process taking place in between, which

is customer specific. We have used Extend SIM to show the processes and the flow and we

showed the number of buses going to the yard due to incomplete works and quality issues,

payment issues and Bus priority. (The Detailed process and attribute description is discussed

above in (Simulation Model Construction).

After this, we tried to find a way to make improvement by reducing the number of buses

proceeding to the yard. We developed a 3D model for the future state by involving welding

robots and ASRS to reduce the lead time and improve quality of work.(Detailed Description is

shown below in 3D Model Description)

3D MODEL DESCRIPTION In 3d Model, station 1 to 4 future model is built.


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FIGURE 4- 3D MODEL – FUTURE MODEL

In Station 1, the parts are dismantled from the bus chassis. The dismantled parts are moved to

station 4, storage instead of sending to warehouse. The parts are moved using forklift. The

storage is handled by having Automated Storage / Retrieval System (AS/RS).

In station 2 & station 3, Station 2 involving welding (body side, front panel, rear panel, floor

welding is done), Station 3 involving roof welding. At present in both the station fully labor force

is involved. In order to finish the work on time and considering quality perspectives robots can

be used. The stations cannot be fully automated; since the robots cannot reach interior places.

Considering these cases the stations are semi-automated.

In Station 4, when the bus chassis arrived at Station 4, the dismantled parts are brought using

AS/RS. The parts are refitted and checked. This is done entirely by labor force.

VALIDITY AND RELEVANCE OF THE MODEL The model in Extend SIM shows the simulation of the Stations 1 to 8, various process involved and customization and to the number of buses to yard which is aim.

Face Validation: The model gives a sound and vivid impression about the major processes, customization attributes and material flow.


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Model assumptions Validation: The work is done mainly on the collected data, it is assumed that data is reliable.

Variability Validation: The model is checked for its reasonable dynamicity in the output for various inputs.

The model is compared the real values for its relevant output for the input. The model is 70% similar to the real model, since we have not included the sub tasks in the process and assumed that all the stations will take exactly 4 hours. The future model visualizes the factory process if changes with the given improvement perspective. We have mentioned that, the tack time reduces when a robot is employed however the exact calculation (tack time) depends on the specifications of the welding process requirement. The improvement and the scenario of the stations 1 to 4 are visualized and validation for the future scope for improving so as to reduce the number of buses going to the yard is established firmly.


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CHAPTER 5


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SIMULATION

RESULTS FROM SIMULATION

By learning the simulation tools, the simulation model for Volvo Buses Station 1 to 8 is modelled

and simulated using ExtendSim software (ExtendSim 7.0).

Finally from execution of the model, we observe that 40% of the buses proceed to

Yard due to following reasons, 20% due to Bus priority, 5% due to Payment issues, 15% due to

Incomplete (pending work in previous stations).

The results are depicted in the graph,


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By learning 3d-Create software, we tried to show a future model for the company involving

robot force and using AS/RS technique. By this concept, the incomplete works in the stations can

be reduced to more than 70%.


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CHAPTER 6


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RESULTS AND CONCLUSIONS From the results (graph) we observe that 40% of the buses proceed to the yard. To reduce this,

o Workers should be made to work in more than 1 station by educating them. By this

labour work force can be reduced to certain amount and all labours will be fully utilised.

o At present, the factory is entirely dependent on the labour force. In the future, by having

balanced & optimal level of labour & automated robotic machines, the quality of work

will improve there by reducing the “Incomplete works in the station” which in turn

reduces the number of buses going to the yard. The standard tack time can be reduced

atleast by 15 to 20 %.

o Bus priority should not be given most often, since it increases the inventory levels of the

company and as well as the cost. Separate scheduling for the bus priority should be

planned.

To conclude, the project provides us deeper insight knowledge about working with the

software’s ExtendSim and 3 d Create. The gained knowledge was applied to solve a problem of

an industry. In our case the current model is analysed using ExtendSim and the futuristic

improved model is visualized using 3d Create software.


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ACKNOWLEDGEMENT We wish to acknowledge our gratitude and appreciation to Johan Ernlund for his support and

feedback for building the Simulation model.

REFERENCES

ExtendSim 8 Manual – User Guide.

3D Create Workshop – October 19th , 2011. Mälardalen University, Eskilstuna.

Chien-Chung Shen,”Discrete Event Simulation on the Internet and the Web”.

Yolanda Carson,”Simulation Optimization: Methods and Applications”, 1997.

http://www.3d-cadcea.co.uk/html/benefits.htm

http://www.3d-cadcea.co.uk/html/benefits.htm


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APPENDIX

3D MODEL – FIGURE

FIGURE 5 - STATION 1


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FIGURE 6 – STATION 2


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EXTENDSIM MODEL


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FIGURE 9 – EXTEND SIM MODEL

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