Modeling and simulation for optimization of a mattress production line based on flexsim software at dunlopillo (vietnam) LTD

MINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING INDUSTRIAL MANAGEMENT MODELING AND SIMULATION FOR OPTIMIZATION OF A MATTRESS PRODUCTION LINE BASED ON FLEXSIM SOFTWARE AT DUNLOPILLO (VIETNAM) LTD SUPERVISOR: MBA NGUYEN DANH HA THAI STUDENT: DO THUY LINH SKL 0 8 Ho Chi Minh City, August, 2021 n MINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING GRADUATION THESIS Topic: MODELING AND SIMULATION FOR OPTIMIZATION OF A MATTRESS PRODUCTION LINE BASED ON FLEXSIM SOFTWARE AT DUNLOPILLO (VIETNAM) LTD Student : Do Thuy Linh ID : 17124047 Year : 2017 Major : Industrial Management Instructor : MBA Nguyen Danh Ha Thai Ho Chi Minh City, August, 2021 n INSTRUCTOR’S COMMENTS Ho Chi Minh City, day … month … year … Instructor i n MEMBER OF THE THESIS COMMITTEE’S COMMENTS -Ho Chi Minh City, day … month … year … Member of the Thesis committee ii n ACKNOWLEDGEMENT The process of completing the graduation thesis is the most important stage in every student's life It is the hardest time for me because I did present the biggest challenge that I’ve never met with full of efforts Graduation thesis gives me an opportunity to review all knowledge and skills in four years of university before starting a career First of all, I would like to express my sincerity, thanks to teachers of the Faculty for High Quality Training and the Faculty of Economy who always have enthusiastically taught and equipped students with all necessary knowledge and experience Secondly, I would like to express my gratitude to my instructor Mr Nguyen Danh Ha who gave me all useful guidance and enthusiastic support They are very valuable suggestions not only in the process of making this thesis but also as a stepping stone for me in the process of studying and setting up a career in the future Finally, thank you to my family and my friends who are always by my side and encourage me to overcome all my hard times Because of the time limit, the difficulty in approaching such a new researching direction i.e Simulation and lack of experience, the thesis cannot avoid mistakes and shortages Therefore, I am extremely appreciated to receive comments and recommendation from you to help me to complete this graduation thesis as well as possible Thank you so much, Best regards Ho Chi Minh City, 18 August 2021 Student DO THUY LINH iii n LIST OF ACRONYMS ACRONYM EXPLANTION Avg Average BN Bonnel (name of the mattress type) DPR Daily Production Report DVL Dunlopillo Vietnam Ltd, MPR Monthly Production Report M&S Modeling and Simulation Pcs Pieces PPR Production Productivity Rate QC Quality Control Qty Quantity iv n LIST OF TABLES Table The advantages and disadvantages of four basic layout types 13 Table 2 Characteristics of a manufacturing system model 19 Table The advantages & disadvantages of Simulation 21 Table The working schedule 24 Table The average daily yield of mattress production system in third quarter, 2020 25 Table 3 The Average Production Productivity Rate per day 26 Table 3.4 The demand forecast for 2023 27 Table List of machines and processing tables in the mattress production line 28 Table Table of processing time of machines and processing tables in the mattress production line 29 Table The output of mattress production line - the actual model 42 Table Detail state of all objects in the Cover Section – Actual simulation model 44 Table Detail Avg stay time and input/output quantity of all objects in the Cover Section – Actual simulation model 45 Table 10 Detail state of all objects in the Spring Section – Actual simulation model 47 Table 11 Detail Avg stay time and input/output quantity of all objects in the Spring Section – Actual simulation model 49 Table 12 Detail state of all objects in the Finishing Section – Actual simulation model 50 Table 13 Detail Avg stay time and input/output quantity of all objects in the Finishing Section – Actual simulation model 51 Table The output of mattress production line - Scenario1 simulation model 54 Table Detail state of all objects in the Cover Section – Scenario1 simulation model 56 Table Detail Avg stay time and input/output quantity of all objects in the Cover Section – Scenario1 simulation model 57 Table 4 Detail state of all objects in the Spring Section – Sncenario1 simulation model 59 Table Detail Avg stay time and input/output quantity of all objects in the Spring Section – Scenario1 simulation model 59 v n Table Detail state of all objects in the Finishing Section – Scenario1 simulation model 61 Table Detail Avg stay time and input/output quantity of all objects in the Finishing Section – Scenario1 simulation model 62 Table The output of mattress production line - Scenario2 simulation model 64 Table Detail state of all objects in the Cover Section – Scenario2 simulation model 66 Table 10 Detail Avg stay time and input/output quantity of all objects in the Cover Section – Scenario2 simulation model 67 Table 11 Detail Avg stay time and input/output quantity of all objects in the Spring Section – Scenario2 simulation model 68 Table 12 Detail state of all objects in the Finishing Section – Scenario2 simulation model 70 Table 13 Detail Avg stay time and input/output quantity of all objects in the Finishing Section – Scenario2 simulation model 71 vi n LIST OF FIGURES Figure Process of the research deployment Figure 1 Image of Dunlopillo Vietnam Ltd Figure Medium End (ME): DUN AUDREY N) MATT 200X180X25CM VN Figure High End (HE): DUN FIRMREST LUXE MATT 205X193X25CM BS Figure Very High End (V-HE): DUN CORINA PRE MATT 200X160X35CM (N) Figure DUN LATEX WORLD PURE MATT 200X160X20CM Figure Factory Organization Chart Figure Volume and variety characteristics for each process type 10 Figure 2 The volume – variety characteristics influence the manufacturing layout 12 Figure The relationship between manufacturing process types and basic layout types 14 Figure A logo image of Flexsim software 20 Figure Mattress production process 24 Figure 2D Layout drawing of Spring Section 30 Figure 3 2D Layout drawing of Cover Section 31 Figure 2D Layout drawing of Finishing Section 31 Figure 3D Logic model of Glue – box station 33 Figure Setup of the Glue-box table 4’s properties for 3D Logic model 33 Figure Setup of the PU Sheet queue’s properties for 3D Logic model 34 Figure Process flow for activities at Glue-box station 35 Figure Setup parameters for Process Flow Properties 35 Figure 10 3D model of process flow for Glue – box station 36 Figure 11 Setup parameters for Source Quilting Top 37 Figure 12 Setup parameters for Quilting Top machine 38 Figure 13 The complete existing 3D model of mattress production line 38 Figure 14 All of process flows for the logic model 40 vii n Figure 15 State of all objects in the Cover Section Pie chart – Actual simulation model 44 Figure 16 Average stay time of Semi – Mattress on Queue in the Cover Section Bar chart – Actual simulation model 46 Figure 17 State of all objects in the Spring Section Pie chart – Actual simulation model 47 Figure 18 Average stay time of Semi – Mattress on Queue in the Spring Section Bar chart – Actual simulation model 48 Figure 19 State of all objects in the Finishing Section Pie chart – Actual simulation model 50 Figure 20 Average stay time of Semi – Mattress on Queue in the Finishing Section Bar chart – Actual simulation model 51 Figure The 3D model design of the Scenario1 54 Figure Pie chart of Cover Section – Scenario1 simulation model 55 Figure Bar chart of Cover Section – Scenario1 simulation model 56 Figure 4 Pie chart of Spring Section– Scenario1 simulation model 58 Figure Bar chart of Spring Section– Scenario1 simulation model 59 Figure Pie chart of Finishing Section– Scenario1 simulation model 61 Figure Bar chart of Finishing Section– Scenario1 simulation model 62 Figure The 3D model design of the Scenario2 64 Figure Pie chart of Cover Section– Scenario2 simulation model 65 Figure 10 Bar chart of Cover Section – Scenario2 simulation model 66 Figure 11 Bar chart of Spring Section – Scenario2 simulation model 68 Figure 12 Pie chart of Finishing Section– Scenario2 simulation model 69 viii n Figure Bar chart of Finishing Section– Scenario1 simulation model Source: Exported from the Scenario1 simulation model – Flexsim 2019 Table Detail Avg stay time and input/output quantity of all objects in the Finishing Section – Scenario1 simulation model No Name of Queue Glue Table Glued Bonnel - Queue Glue Table Glued Bonnel - Queue Tape Conveyor BN - Queue Glue Table Glued CPS - Queue Tape 10 Conveyor CPS - Queue 11 Glue Table 12 Glued IPS – Queue 13 Tape 14 Conveyor IPS - Queue 15 Tape 16 Conveyor BN - Queue Avg Stay time Input Output (minute) (pcs) (pcs) 61 61 61 61 59 59 59 59 120 120 120 120 49 49 49 49 49 49 49 49 45 45 45 45 23 23 23 23 22 22 22 22 0 0,5 0,1 0,4 0,1 62 n 17 QC Finished Mattress 140 140 18 QC Finished Mattress 74 74 19 Checked Mattress 214 214 20 Packaging 214 214 21 Duchess Top 449 45 45 22 Duchess Bottom 495,6 45 45 23 Duchess Border 602,2 45 45 24 Marilyn Top 713,7 50 49 25 Marilyn Bottom 587,5 50 49 26 Marilyn Border 662,4 50 49 27 Contract Top 870,2 120 120 28 Contract Bottom 758,8 120 120 184 826,4 120 120 29 Contract Border Source: Exported from the Scenario1 simulation model – Flexsim 2019 4.2 Scenario2 for capacity improvement of the mattress production line 4.2.1 Design of the Scenario2 After analyzing the result of the Scenario1, we can realize how effective it is It solves almost the problems of the existing production However, it still doesn’t have enough ability to cover all the demand forecast Therefore, Scenario2 will be design for enhancing the capacity of the production line based on the Scenario1 The analysis in the Scenario1 showed trouble with the shortage of Duchess mattress quantity for the demand, so the Scenario2 will pay attention on it Through all the solutions of capacity improvement are mentioned in the former section, the design of Scenario2 follows:  Cover production line:  Produce extra 11 cover sets of Duchess mattresses  Sewing Top 1, Sewing Top and Sewing Bottom need to work overtime for extra hour, so the total working overtime is hours 63 n  Spring production line:  Add more Combiner IPS processing table and workers for working shift a day i.e Shift  Finishing production line:  Glue – box table4, Tape4 and their workers in shift work overtime hours The design for 3D model of Scenario2 in Flesxim software is shown by Figure 4.8 Figure The 3D model design of the Scenario2 Source: Exported from the Scenario2 simulation model – Flexsim 2019 4.2.2 Result and analysis of the effectiveness of the Scenario2 Table The output of mattress production line - Scenario2 simulation model Unit: pcs Total Contract Duchess Marilyn Finished goods 227 120 58 49 Spring 231 123 59 49 Top 230 120 60 50 Bottom 230 120 60 50 Border 230 120 60 50 Cover: Source: Exported from the Scenario2 simulation model – Flexsim 2019 64 n As results shown in Table 4.8, the finished goods produced a day of the Scenario2 can completely satisfy the demand forecast To assess the effectiveness of this one, a detail analysis for each Section are carried out below: In Cover Section: Through Figure 4.9 and Table 4.9, compare with the results of Scenario1, idle time problem is reduced significantly, equipment and machines are used more efficiently by increasing production of Duchess mattress Although the changes of the Scenario2 cannot minimize the idle time, it is still a good choice to meet the requirements at the present Moreover, the production capacity of the Cover Section can deal with even higher demand Therefore, this analysis will probably be able to be valuable references for other future projects Figure Pie chart of Cover Section– Scenario2 simulation model Source: Exported from the Scenario2 simulation model – Flexsim 2019 65 n Table Detail state of all objects in the Cover Section – Scenario2 simulation model No Name of Machine Idle time No Name of Machine Idle time (%) (%) Quilting Top 6,9 Hemming Border 23,1 Hemming Top 21 10 Embroidery 39,5 Sewing Top 23,9 11 Sewing Join 17,2 Sewing Top 24,3 12 Sewing Label 53,9 QuiltingBottom& Border 21,4 13 Sewing Label 11,7 Cutting 74,5 14 QC Cover 60,9 Hemming Bottom 28,6 15 QC Cover 36,6 Sewing Bottom 15,2 Source: Exported from the Scenario2 simulation model – Flexsim 2019 Based on the Table 4.10, working overtime in Sewing Top and Bottom helps the Cover Section to handle all the increase of Duchess mattress from 215 to 230 sets in one day The Avg stay time of item on Queues is still maintained as the Scenario1, except the Avg stay time of Hemmed Top and Hemmed Bottom, it increases a little bit because of the extra overtime In general, both the output and Avg stay time in Cover Section meet the target set forth for the demand forecast Figure 10 Bar chart of Cover Section – Scenario2 simulation model Source: Exported from the Scenario2 simulation model – Flexsim 2019 66 n Table 10 Detail Avg stay time and input/output quantity of all objects in the Cover Section – Scenario2 simulation model No Name of Object Avg Staytime Input Output (minute) (pcs) (pcs) 230 230 230 Source quilting Top Quilting Top Quilted Top - Queue 0,4 230 230 Quilted Top - Queue 3,7 230 230 Hemming Top 230 230 Hemmed Top - Queue 230 230 Sewing Top 113 113 Sewing Top 111 111 Sewed Top – Queue 0,2 230 230 10 11 12 Source Bottom & Border Quilting Bottom & Border Quilted Bottom - Queue 0,1 253 230 253 253 230 13 Quilted Bottom - Queue 36,5 230 230 14 Hemming Bottom 230 230 15 Hemmed Bottom - Queue 83,7 230 230 16 17 Sewing Bottom Sewed Bottom - Queue 0,1 236 230 236 230 18 Quilted Border - Queue 23 23 19 Cutting 23 230 20 Cut Border - Queue 48,5 230 230 21 22 Hemming Border Hemmed Border - Queue 13,2 230 230 230 230 23 Embroidery 230 230 24 Embroidered Border - Queue 230 230 25 Sewing join 230 230 27 Joined Border 27,6 230 230 28 29 31 Sewing label Sewing label Sewed label Border 0,1 63 167 230 63 167 230 17,5 18,3 332 32 QC Cover 358 33 QC Cover Source: Exported from the Scenario2 simulation model – Flexsim 2019 67 n 332 358 In Spring Section: Everything in Spring Section is unchanged from the previous Scenario except for the appearance of the Combiner IPS2 so that I just concentrate on this change Through the Table 4.11, the Avg stay time of Coiled IPS on Queue is reduced from 752 minutes to 344,5 minutes and the output of IPS Spring is also increased by 14 units per day (from 45 to 59 units) Therefore, it makes the operation of this Section more effective and creates more springs to meet the demand Figure 11 Bar chart of Spring Section – Scenario2 simulation model Source: Exported from the Scenario2 simulation model – Flexsim 2019 Table 11 Detail Avg stay time and input/output quantity of all objects in the Spring Section – Scenario2 simulation model No Name of Queue Avg Stay time Input Output (minute) (pcs) (pcs) Source BN 61.000 BN Coiler 61.000 61.000 Coiled BN – Queue 61.000 53.802 Assemble BN 53.802 123 Assembled BN – Queue 123 103 Clip & Bend 105 105 Clip & Bend 18 18 123 123 29.107 BN Spring Unit - Queue Source CPS CPS Coiler 10 Coiled CPS - Queue 248,1 87,1 260,6 29.107 659 68 n 29.107 21.609 11 Fold Nonwoven 21.609 49 12 Folded CPS - Queue 49 49 13 Assemble CPS 49 49 14 CPS Spring Unit - Queue 49 49 15 Source IPS 28.834 16 IPS Coiler 28.834 28.834 17 Coiled IPS - Queue 28.834 25520 18 Combiner IPS 18.920 43 19 Combiner IPS 7.040 16 0,1 123,4 344,5 534,3 59 58 20 IPS Spring Unit - Queue Source: Exported from the Scenario2 simulation model – Flexsim 2019 In Finishing Section: Base on the Figure 4.12 and Table 4.12, there is only the state of Tape2 and Tape4 machine different from the Scenario1 Both machines reduce significantly their idle time (from 32.7% to 20.1%, 31.2% to 17.6% respectively) due to the increase of IPS Spring It can be seen that the Finishing Section can work continuously Figure 12 Pie chart of Finishing Section– Scenario2 simulation model Source: Exported from the Scenario2 simulation model – Flexsim 2019 69 n Table 12 Detail state of all objects in the Finishing Section – Scenario2 simulation model No Name of Machine Idle time No (%) Name of Idle time Machine (%) Glue box table Tape 1,2 Glue box table Tape 17,6 Glue box table 2,9 QC Finished 64 Glue box table 10 80,4 Tape 5,5 11 QC Finished Mattress Packaging Mattres 20,1 Tape Source: Exported from the Scenario2 simulation model – Flexsim 2019 Moreover, by using overtime, Tape4 machines, and Glued – Table4 can make more Glued IPS, from 45 to 58 pcs which is more than the quantity of forecasting demand i.e 56 pcs, as shown in Table 4.13 Besides, Avg stay time of Glued IPS and Checked mattress is increased by 36,5 and 39,3 minutes due to the rise of Duchess mattress quantity However, the Scenario2 still can handle well these semi products on Queue and finished goods per day increase by 13 pcs from 214 to 227 Figure Bar chart of Finishing Section– Scenario2 simulation model Source: Exported from the Scenario2 simulation model – Flexsim 2019 70 n Table 13 Detail Avg stay time and input/output quantity of all objects in the Finishing Section – Scenario2 simulation model No Name of Queue Glue Table Glued Bonnel - Queue Glue Table Glued Bonnel - Queue Tape Conveyor BN - Queue Glue Table Glued CPS - Queue Tape 10 Conveyor CPS - Queue 11 Glue Table 12 Glued IPS – Queue 13 Tape 14 Conveyor IPS - Queue 15 Tape 16 Conveyor BN - Queue 17 Avg Stay time Input Output (minute) (pcs) (pcs) 61 61 61 61 59 59 59 59 120 120 120 120 49 49 49 49 49 49 49 49 58 58 58 58 33 33 33 33 25 25 25 25 QC Finished Mattress 143 143 18 QC Finished Mattress 84 84 19 Checked Mattress 227 227 20 Packaging 227 227 21 Duchess Top 488,2 60 58 22 Duchess Bottom 525,9 60 58 23 Duchess Border 382,6 60 58 24 Marilyn Top 713,6 50 49 25 Marilyn Bottom 525,9 50 49 26 Marilyn Border 662,4 50 49 27 Contract Top 869,2 120 120 28 Contract Bottom 757,8 120 120 0 0,5 5,2 0,1 42,5 0,4 0,1 223,3 825,4 120 120 29 Contract Border Source: Exported from the Scenario2 simulation model – Flexsim 2019 71 n CONCLUSION By using Flexsim simulation software version 2019 for this study and all solutions are pointed out in two Scenarios, the mattress production line is improved both efficiency of machines and the quantity of finished mattresses leading to the future demand covered Therefore, the thesis achieved the objectives stated Based on the statistic results from Scenarios, the quantity of finished mattresses improves significantly from 141 to 227 pcs per day which is approximately increased 61% Specially, the Scenario1 plays an important role in the increase by solving bottlenecks and utilizing all the current resources That is:  Adding more Clip – bend processing table helps the Bonnel Spring increase 20% (from 103 to 123 units) leading to Glue – Box1 & Glue - Box2 working more efficiently with no idle time (Reduce from 10,3% and 9,5% to 0, respectively), and the Avg stay time of Assembled Bonnel on Queue is reduced by 228,4 minutes (from 315,6 to 87,2 minutes)  Changing the task of Tape2 machine from Tape-edge Bonnel to IPS mattress: Tape1 machine is utilized more effectively whose idle time is reduced from 62% to 7,1% The idle time of Tape2 machine also decreases from 62,8% to 32,7%  Working overtime at Sewing Top and Bottom station and adding one more shift for Packaging help solve all the semi – mattress waiting on Queue Additionally, the Scenario2 also contributes the enhancement of finished mattress quantity by increasing the capability of Duchess mattress production to meet the forecasting demand:  Adding one more Combiner IPS processing table makes the number of IPS Spring units rise from 45 to 59 unit  Working overtime at Glue – Box4, Tape and at Sewing Top & Bottom station: Duchess mattress numbers reach 58 pcs a day from 45 pcs in the Scenario1 contributing to the overall increase of Finished mattresses i.e 227 pcs In general, based on the objectives and principles of low cost and output increase, the improvements and changes that have been suggested in the thesis are quite easy to 72 n follow, and the cost for application is reasonable because existing machines are utilized more efficiently, and the added parts are semi-automatic machine and manual processing table which are not expensive to invest Besides, the proposed solutions still have limitation The first one is the constant overtime usage at Sewing Top & Bottom station, Glue – Box4, Tape4 machine and Clip – Bend2 Although overtime has a lot advantages such as reducing the cost of training new employees, creating more jobs to increase incomes for employees, stabilizing human resources However, using overtime in continuous time will lead to consequences such as reducing productivity because of worker’s health decline and high overtime costs That's why this needs to be considered more carefully to solve it satisfactorily The second limitation is long time consuming It took more than months since the idea has been raised until the study is completed The third one is the lack of modeller’s experience and skills so that the quality of the analysis may not be completely accurate, it needs more assessment from specialist to make sure the result of this study valuable 73 n REFERENCES Công Thương (19/10/2020) Cuộc đua cạnh tranh thị trường nệm Retrieved from: https://congthuong.vn/cuoc-dua-canh-tranh-tren-thi-truong-nem-126957.html Axelrod, R (1997) Advancing the Art of Simulation in the Social Sciences Simulating Social Phenomena, 21–40 doi:10.1007/978-3-662-03366-1_2 Banks, J (Ed.) (1998): Handbook of Simulation: Principles, Methodology, Advances, Applications, and Practice New York, America: John Wiley and Sons Publisher Beaverstock, M., Greenwood, A., Nordgren, W (2017) Applied Simulation: Modeling and Analysis using Flexsim (5th ed.) Orem, Utah: FlexSim Software Products, Inc Publisher Clark, R., and Krahl, D (2011) Roadmap to Success: Your First Simulation Model In Proceedings of the 2011 Winter Simulation Conference, 1465-1475 doi:10.1109/wsc.2011.6147865 Connors, M (2020, May, 21) The two types of bottlenecks in manufacturing, and what you can about them Retrieved from https://www.geniuserp.com Dooley, K 2002 Simulation research methods Companion to organizations, 829 – 848 doi:10.1002/9781405164061.ch36 Ericson, A (2017) Bottleneck detection in manufacturing: A throughput case study at SCANIA CV Master thesis, Chalmers University of Technology Harrell, C., Ghosh, B.K., & Bowden, R (2012) Simulation Using Pro Model New York, America: McGrawHill Publisher Heilala, J (1999) Use of simulation in manufacturing and logistics systems planning VTT Manufacturing Technology, Finland Katana (2019, Sep 25) How to Master Bottleneck Management in Production Process Retrieved from: https://www.katanamrp.com Law, A.M & Kelton, W.D (1991) Simulation Modeling & Analysis New York, America: McGraw Hill Publisher Lawrence, S R., and Buss, A H 1995 Economic Analysis of Production Bottlenecks Mathematical Problems in Engineering, 1(4), 341-369 74 n Maria, A (1997) Introduction to modeling and simulation Proceedings of the 29th conference on Winter Simulation, 7-13 doi:10.1145/268437.268440 Panvan, K.K (2020), April 15) System Simulation, Modelling & Visualization Retrieved from https://www.howandwhentoreference.com Robinson, S 2007 A Statistical Process Control Approach to Selecting a Warm-Up Period for a Discrete Event Simulation European Journal of Operational Research 176(1):332–346 Roser, C., Lorentzen, K., Deuse, J (2015) Reliable shop floor bottleneck detection for flow lines through process and inventory observations: the bottleneck walk Logistics Research, 8(1), 1-9 doi:10.1007/s12159-015-0127-2 Slack, N., Chambers, S., Jonston, R (Eds.) (2010) Operations management (6th ed.) New Jersey, America: Prentice Hall Publisher Yu, C., Matta, A (2014) Data-driven bottleneck detection in manufacturing systems: A statistical approach 2014 IEEE International Conference on Automation Science and Engineering (CASE), 710-715 doi:10.1109/coase.2014.6899406 75 n S n K L 0