PRODUCTIVITY IMPROVEMENT IN THE ASEEMBLY FLOW-LINE
AZHAR RAJA DURAI PANDI
KTH ROYAL INSTITUTE OF TECHNOLOGY
Masters in Production Engineering and Management
Productivity Improvement in the Assembly Flow-Line
School of Industrial Engineering and Management Department of Production Engineering
MASTER THESIS
Report done by Azhar Raja Durai Pandi
Supervisor at KTH Daniel Tesfamariam Semere
Supervisor at FAIVELEY TRANSPORTS
Vinayagam
Abstract
As the material feeding system has the great impact on the assembly flow-line which enhances the productivity thereby improves company’s profit. The purpose of this thesis is mainly focused on the flexibility usage of the material handling/feeding system into the line which helps in improving the productivity. The new design for the material handling trolley was designed and also came up with the additional concept of kitting and palletizing the parts in the newly designed trolley which helps in easy handling for the operators and improves the productivity as well. The appropriate analysis and comparison corresponding to the productivity time was done with the existing material handling trolley and with the newly designed trolley. In addition to this, proposed ideas for enhancing the assembly flow line and successfully proved that material handling system, kitting and palletizing plays a very important role in productivity improvement of the assembly flow line.
Abstrakt
Eftersom materialmatningssystemet har stor inverkan på aggregatets flödesledning som förbättrar produktiviteten förbättrar därmed företagets vinst. Syftet med denna avhandling är huvudsakligen inriktat på flexibilitetsanvändningen av materialhanterings- / matningssystemet i linjen som hjälper till att förbättra produktiviteten. Den nya konstruktionen för materialhanteringsvagnen är utformad och har även tagit fram ytterligare konceptet med kittning och palletering av delarna i den nybyggda vagnen, vilket hjälper till att hantera operatörerna enkelt och att förbättra produktiviteten också. Den lämpliga analysen och jämförelsen som motsvarade produktivitetstiden gjordes med den befintliga materialhanteringsvagnen och med den nyutvecklade vagnen. Utöver detta har förslag till idéer för att förbättra sammansättningsflödet och framgångsrikt visat att materialhanteringssystemet, kittning och palletering spelar en mycket viktig roll i produktivitetsförbättring av aggregatets flödesledning.
Acknowledgement
First of all I would be much more gratitude to Department of Production Engineering and Management, KTH Royal Institute of Technology for giving me this thesis opportunity. I thank Mr. Lasse Wingård, Department head, Mr. Per Johansson, Mr. Ove Bayard, who rendered his full support for this thesis work. I like to express my sincere and special gratitude to my supervisor Mr. Daniel Tesfamariam Semere who supported me with the patience and guided me well during my thesis work and helped to do this challenging task easily.
I am thankful and also express my gratitude to Mr. Vinayagam, General Manager, PED, Mr.
Saravanan, Assistant Manager, PED, Faiveley Transports – A Wabtec Company for assistance and encouragement who are my supervisor to accomplish this assignment and their valuable guidance and supported me to present this thesis report in a success manner. Also to Mr.
Somasundaram, Human Resource, Faiveley Transports – A Wabtec Company and also few industry persons for giving such attention and time for supporting me with this thesis work.
Finally, the last but not least my happy gratitude goes to my parents and family members and all of dear friends who directly or indirectly helped me to complete this thesis report
successfully.
Table of Contents
Abstract... 3
Abstrakt ... 5
Acknowledgement ... 7
Table of Contents ... 8
Abbreviations ... 10
List of Figures ... 11
List of Tables ... 12
1. Company Introduction ... 13
2. Background ... 14
2.1 Problem Description ... 14
2.2 Limitations ... 15
2.3 Problems Identified in The Assembly Line ... 16
3. Methodology ... 18
4. Literature Review ... 19
4.1 Material Handling System ... 19
4.2 Continuous Supply... 20
4.3 Batch Supply ... 20
4.4 Kitting ... 21
4.5 Benefits of kitting ... 21
4.6 Palletizing ... 22
5. Bogie Brakes ... 24
5.1 TBU Assembly ... 24
6. Production Lean Tools ... 27
6.1 Value Stream Mapping ... 27
6.1.1 Current State ... 27
6.1.2 Analysis of Current State ... 27
6.1.3 Proposed Improvements ... 28
6.1.4 Result ... 28
6.2 5S ... 31
6.3 Kaizen ... 31
6.4 Toyota Way 14 Principles ... 32
7. Current Material Handling/Feeding System ... 33
7.1 Effects Of Current Material Feeding System ... 34
7.2 Current Trolley ... 35
7.3 Current Workbench and Bin trolley ... 36
7.4 CAD Modelling ... 38
7.5 Kitting Concept ... 39
7.6 Palletizing Concept ... 39
8. Discussion ... 44
8.1 Operators Feedback ... 44
8.2 Revision of the Design ... 44
8.3 Selection of Materials ... 45
9. Market Study for Suppliers ... 46
9.1 Benchmarking and Suppliers for Material Handling Trolley ... 46
9.2 Evaluation of Suppliers and Outcomes ... 46
10. Reconsideration of the Design... 48
11. Analysis and Result ... 50
12. Future Development ... 53
13. Conclusion ... 56
14. Reference ... 57
Appendix ... 60
Abbreviations
MHS - Material Handling System VSM - Value Stream Mapping TBU - Tread Brake Unit
PP - Poly-Propylene
HDPE - High Density Poly-Ethylene SMH - Standard Man Hour
List of Figures
Figure 1: Flowchart of the Methodology ... 18
Figure 2: Principles of MHS ... 20
Figure 3: Current layout of workstations in TBU assembly line ... 26
Figure 4: Current state of TBU assembly line (service brake)... 29
Figure 5: Future state of TBU assembly line (service brake) ... 30
Figure 6: Effects of current MHS ... 35
Figure 7: Current trolleys for TBU assembly line ... 36
Figure 8: Current trolleys for TBU assembly lin ... 36
Figure 9: Current workbench and bin trolley. ... 37
Figure 10: New trolley design for MHS ... 38
Figure 11: Shoe holder pallet ... 41
Figure 12: Housing pallet ... 42
Figure 13: Parking unit pallet ... 43
Figure 14: Final design A ... 48
Figure 15: Final design B ... 48
Figure 16 : 2D drafting of final trolley design ... 49
Figure 17: Current analysis of TBU assembly line (service brake) ... 51
Figure 18: Future analysis of TBU assembly line (service brake) ... 51
Figure 19: Before implementation of new MHS ... 54
Figure 20: After implementation of new MHS ... 54
List of Tables
Table 1: SMH time for service brake assembly ... 25
Table 2: SMH time for parking brake assembly ... 25
Table 3: MHS time study ... 33
Table 4: Part list for shoe holder pallet ... 41
Table 5: Parts list for housing pallet ... 42
Table 6: Parts list for parking unit pallet ... 43
Table 7: Selection of materials ... 45
Table 8: Cost of trolley and pallets (in PP) in inr ... 46
Table 9: Cost of trolley and pallets (in HDPE) in inr ... 47
Table 10: Cost of trolley and pallets in sek... 47
1. Company Introduction
Faiveley Rail Transport India Limited is one among the leading manufacturer & exporter of huge variety of train and metro rail products, developing trust for the customers by providing the best quality with lot of comfort, managing best safety systems in the train, better management of the electrical and electronic in the platform and also proving more services.
Faiveley Rail Transport India Limited Transports (FTIL) has become the global leader in terms of designing and manufacturing of huge variety of products which are used in the rail industry and the products that are included are like, advanced braking systems, doors and doors electronic systems, brake panels, coupler systems and more electronic products. The industry in India, the company manufacture and supplies the products like, brake control panels, air conditioning product, and service & parking brakes and couplers as well for the country's rail network. The company supplies their product to many customers across India, they are, Delhi metro Rail Corporation, Kochi Metro Rail Corporation, Chennai Metro Rail Corporation and also to Indian Railways. Most of the orders for the company is from the Delhi Metro Rail Corporation. In addition to designing complex systems for the Indian rail market, the highly trained team of engineers at FTIL also support their five global centres of competence for various design and development works [1].
FTIL is the rail industry that works under the Faiveley Group, which is in France and also the company’s headquarters and has their operations in around 13 countries across the world. On 30 November 2016, Wabtec Corporation acquired a 51% majority ownership of Faiveley Transport, after completing the purchase of the Faiveley family’s stake. The strategic combination of Wabtec and Faiveley Transport creates one of the world’s largest public rail equipment companies, with revenues of about $4.2 billion and a presence in all key transit and freight rail markets worldwide [1].
2. Background
The project is about strategically planning and improvising the production line and also balancing the flow line by using line balancing techniques and implementing kaizen (continuous improvement) in the production line. This particular thesis work is well suitable for the Production Engineering and Basic Manufacturing Technology skill set.
2.1 Problem Description
The problem description of this particular Thesis Work is, the company being a manufacturing company has a production line, which is used to assemble of braking systems for normal trains and also for metro trains. We have an existing production line but since it is not optimized, this thesis work would be focused on improving the efficiency of the production line thus optimizing production. An important and challenging task in this thesis work would be, kaizen or continuous improvement which tends to productivity improvement. Although this is a challenging task, this is something that the company has been working on and we would the thesis work to come up with specific methods as to how this could be implemented and implement it in the company. Further the purpose of the thesis work should completely have focused on the material handling systems which helps in enhancing the productivity such that all the parts which are required for the particular workstation have to be loaded in a single material handling trolley and it has to done for three major workstations of the TBU line. Besides these mentioned areas for improvement of the thesis work, the work has to come up with better solutions to improve the productivity. In addition to this the company has designed the new layout in which the possible proposal ideas for the productivity improvement can be proposed considering the appropriate production lean tools.
The major problems are as follows,
• The existing production line is not well organized.
• The Material Handling System (MHS) is not well planned and designed (i.e the parts feed into the assembly line through material handling trolley)
• Too much of manual operations.
• Non-value-added time during the Material Handing has impact on productivity thereby increases the time for assembly process.
2.2 Limitations
As this is the master thesis which is the most important course which added the value to the master degree student to fulfil his degree that is linked to the master program course. A few limitations have to be made in order for this project to be feasible one.
Productivity improvement in the bogie brakes assembly. There are three assembly lines in the bogie brakes assembly which includes TBU assembly line, Actuators assembly line and Calipers assembly line. The project is to enhance the productivity in the TBU assembly line by improving the better material feeding system. The TBU assembly lines has five major assembly workstations. They are, shoe holder assembly, housing assembly, parking assembly, suspension/support-arm link assembly and main assembly. Then followed by the testing, inspection, storage and dispatch. There are three variants of products that are assembled in this line, (i) Indian Railways, (ii) Riyadh Metro and (iii) Kochi Metro (KMRL). The TBU assembly line consists of assembling of two products such as (i) service brakes and (ii) parking brakes for all the three variants. Limited to work with Thread Brake Unit (TBU) assembly line and further again limited to work on Service TBU . Trolley Design for both Service & Parking TBU.
In current scenario, there are two to three operators working for the five major assemblies depends on the demand needed such that one person has to do the entire job of these five major assemblies that are mentioned above. In a day there are two shifts, each shift has 8 hours in which 45 minutes is for lunch and tea breaks. Each individual operator is managing to assemble two complete TBU assembly in one shift. Whereas the actual plan is to complete 10 numbers but they are assembling only 4 or 6 per shift based on the man power. The operators are walking around 10 to 20 seconds for picking up the one part which is required for the assembly as the trolleys are placed 3 to 3.5 meters from the workstation. On the whole, the operators are walking around 15 minutes approximately for the material handling. Also, there are mixed up of parts in the trolleys for different workstations. The reason behind this is, few parts are coming from the paint shop and few parts are coming from the stores and the parts are of different shapes and sizes. Then they are brought in separate trolley near to the workstation.
Each particular assembly consists of many small child parts which are stored in the bins in bin
trolley in front of the workstation. The tools required for the assembly operations are kept in a rack below to the workbench.
For this case, the engineers in the process engineering development has designed one new layout and in which they need this thesis work to be more focused on material feeding system that helps in productivity improvement. In the new layout, the trolley is approximately around 0.8 meters from each workstation. The constraints for the new trolley design should be in such a manner that, one trolley should hold almost all 10 complete assemblies’ A and B class parts which are required for the appropriate workstation and the trolley should be more flexible and easy for the operators to handle ergonomically and perform their job easily. Also, the cost of the trolley should be very cost effective.
As mentioned, there are several different sizes of the parts which have to be loaded in the material handling trolley. In this project, the focus is limited to develop the new material handing trolley design for 3 major workstations. Apparently the productivity improvement through the better solutions of material handling system includes a lot of processes and parts, the focus will be towards the most time consuming processes which comes under non-value activity such as walking and searching of parts. These processes are mainly concerning the very basic processes of the activities carried out in the assembly line. Therefore, this project focuses mainly on above mentioned parts with the given constraints.
2.3 Problems Identified in The Assembly Line
The detail study of the whole TBU assembly line and also all the possible details necessary for the material handling system was done successfully. From the above mentioned case study, there are many risks and problems are identified and also got the feedbacks from the operator such that the risks they are facing with the current material handling trolleys.
The following risks and problems that are identified in the assembly flow-line are as follows,
• The parts are loaded in the three different trolleys like, painted parts in one trolley, other stores parts in another two trolleys and child parts in bin trolleys. By this there
is no standard trolleys for particular workstation and operators take more time in searching of parts to pick up.
• Most of the operations are performed manually which tends to very time consuming.
• The material feeding system is not standardized and its time consuming.
• Non-value activities such as walking and searching for tools & parts.
• Picking up the tools are in the rack below the workbench which is not ergonomic.
• Lifting of heavy parts manually from the major 3 workstations to the main assembly workstation which is also not ergonomic.
• In some cases, if the unavailability of parts which is required for the appropriate workstation then the entire line stops as the whole assembly operation is done by a single operator.
• Child parts in bin trolleys are not loaded with sequence of the assembly order which results in confusion and time consuming.
• MHS is not standard and also not flexible.
3. Methodology
This is the methodology to be followed for the successful completion of the project.
Figure 1: Flowchart of the Methodology
4. Literature Review
The literatures which are closely related to this thesis is taken as reference and also those literature helped to finish this challenging thesis work in efficient way.
4.1 Material Handling System
Surinder Kumar et al [2] examined about the material handling system (MHS) and in which it is clearly seen that the material handling system (MHS) in the assembly line plays a vital role among the performance and the productivity of the assembly line. So that, MHS should be properly planned and designed and also it should be placed at right time, right sequence and so on.
Art Smalley [3] investigated about the Toyota's New Material-Handling System that shows TPS's Flexibility states that Toyota Motor Corporation has introduced a new material-handling system based on kitting to reduce complexity and improve quality in assembly areas. Also the kiting concept helps in minimizing three-forth the time of the MHS.
Seran Akincilar et al [4] have planned to design an in-plant MHS that could be more ergonomic and improves production efficiency. In recent modern industries, the scenario is that in order to stay competitive in the industrial market, companies need to achieve the quality in both customer satisfaction and cost reduction in production operations. Material Handling Systems (MHS) is the place to achieve this challenging goal, as such it have the direct impact on production.
Vieira, G. B. B. et al [5] focused on improvements in internal materials handling management, approaching the high profile company like the automotive industry. Materials handling system and the production flow are well co-related in general. Due to this, transit time, resources usage, and service levels were having high impact through MHS. The authors’ objectives were, evaluation of the impact based on materials handling management over the internal customers’
perceptions of cost, safety, service, agility and satisfaction which is a systematic approach.
Johansson [6] analysed about the materials feeding has the important role in identifying the right principle, and which will suits well for feeding the materials to a workstation or an assembly line. have categorised some various principles upon feeding materials to a workstation or an assembly line which includes continuous supply, batch supply and kitting.
These are shown in Figure 1 as follows, and the categorised principles are based on,
• Selection of part numbers or all part numbers
• Sorted by part numbers or assembly object.
Figure 2: Principles of MHS
4.2 Continuous Supply
Johansson [6] gave the description about continuous supply such that the materials are distributed to the assembly stations in units suitable for handling for an assembly operation and where these units are replaced when they are empty. There is no replacements of different part numbers rather than that all parts are available at the assembly station at every time for the assembly of products. Reloading of parts are often done by store person, either in bins, or in trolleys.
4.3 Batch Supply
Johansson [6] gave the brief description on Batch Supply such that the materials are supplied for various products to be assembled. The batch of materials can be a batch of required part numbers or in fixed batch quantities. Apparently it differs from the continuous supply such that only less part numbers which are required for the batch assembly have to be loaded and stored near the work station.
BATCH CONTINUOUS
KITTING -
SELECTION OF PART NUMBERS
SORTED BY PART NUMBER
ALL PART NUMBERS
SORTED BY ASSEMBLY OBJECT
4.4 Kitting
In most of production/manufacturing companies, the loading of parts required for sub- assemblies and major assemblies operation to the shop floor in pre-determined numbers that are placed near workstation either in bins or trolleys is known as kitting.
Johansson [6] view on kitting states that for one complete assembled product, the parts which are required for that product will be collected and kept as a kitting parts near the work station.
Also the kitting is completely different from the batch supply and also kitting helps in productivity improvement. Further the kitting is then discussed in detail.
Jimesh M. Gajjar [7] demonstrated that the material feeding/handling principle of kitting across the in-plant the material supply in the assembly line. With this principle, parts are loaded very close to the appropriate workstation to perform the assembly operations in pre-sorted kits, such that the each kit containing parts for one complete assembly of the part of that particular workstation.
Johansson [8] examined the kiting concept in which a kitting process is well-suited for parallelized flow in an assembly line, product that assembled with many part numbers, quality assurance products and parts of high value.
Ding et al [9] describes the concept of kitting which plays a key role in industries which includes electronics industry, which co-relates with small parts and performs assembly operations repeatedly, JIT-system which manages larger parts to be assembled has more benefits from kitting concept.
4.5 Benefits of kitting
Bozer Y.A. et al [10-13] analysed about the benefits of kiting. The kitting the most effective principle in MHS has some benefits which are as follows:
• Saves shop-floor space in manufacturing/production plant
• Reduces assembly operators’ walking and searching times which are non-value added activities
• Controls production time at every workstations in assembly line and reduces Work In Progress (WIP).
• Reduces or facilitates material delivery to workstations by eliminating the need to supply individual component containers.
• Increases product quality, reducing the frequency of wrong parts in the end product or missing parts in the end product.
• By reducing operators search time for parts through kitting which becomes very flexible for assembly operations and makes easy for training the new employees.
4.6 Palletizing
In manufacturing/production industries, the loading and unloading of parts or components to or from pallets are basically known as palletizing.
Rahul. V. Mahajan et al [14] explained about the palletizing systems plays a key role in flexible way of material handling system to enhance productivity. Palletizing system is a concept which is designed concerning the performance and flexibility of the productivity in the assembly/manufacturing line. In recent scenario, palletizing system and its installation and then its integration with material handling system within the in-plant are the parameters to concern highly for the good industrial engineer.
Adsavakulchai S (2014) [15] describes that palletizing play a vital role in manufacturing/production industries in flexible transportation in shop-floor. Palletizing helps to enhance fast transport of parts and reduces transport cost and helps to optimize space in shop-floor and also carries heavy load capacity.
4.7 Polymers (HDPE Vs PP)
Sihama E. Salih et al [16] has investigated various effects of the blend ratio of HDPE : PP and LDPE : PP with its mechanical properties and the end results of this particular investigation are: (i) The mechanical properties of HDPE : PP blends resulted with the higher values when compared to mechanical properties of LDPE : PP blends. 2) Mechanical properties that includes Tensile strength, Fracture stress, Young modulus, Bending modulus, creep modulus
and hardness of both HDPE : PP and LDPE : PP blend are clearly seen that its mechanical properties increases based on the increment of PP weight percentage. But there is the exceptional on elongation which seems to be decreased.
Barbara O. Calcagno et al [17] described that the HDPE and PP polymers are basically processed by injection moulding. They are highly useful in many applications and it has a wide range of industrial and household applications. Polypropylene (PP) and high-density polyethylene (HDPE) are known as semi-crystalline polymers which are widely used in industrial applications such as packaging, coatings, composite materials, and house and automobile functional parts. HDPE generally a tough polymer with low strength and stiffness, high elongation at break and also less dense than other polymers. Coming to PP, the properties of PP reveals that it has high dynamic loading capacity and higher strength and stiffness compared to HDPE.
5. Bogie Brakes
All brakes which are used in railways are generally air brakes. They use fail-safe brake system (even the brake fails it manage to apply the brake). Different types of bogie brakes, in that 1)TBU (Tread brake unit)
2)WMD (Wheel mounted disc brake) 3)AMD (Axle mounted disc brake)
4)BMBE (Bogie mounted brake equipment)
5.1 TBU Assembly
TBU work based on the Pneumatic - Mechanical operated brakes (A mechanism which pushes the brake shoe to tread of wheels driven by compressed air). It is based on fail brake system. One bogie consists of 8 Service TBU and other 4 are Parking TBU. It has the
capability for the speed of 120 kmph.
Productivity improvement in the TBU assembly line is the main goal of this thesis work. There are three assembly lines in the bogie brakes assembly which includes TBU assembly line, Actuators assembly line and Calipers assembly line. The project is to enhance the productivity in the TBU assembly line by improving the better material feeding system. Then the TBU is categorized into two types of brakes such as service brake and parking brake. The TBU lines has four major assemblies with three workstations. The four major assemblies are, shoe holder assembly, housing assembly, suspension/support-arm link assembly and main assembly. The above mentioned four assemblies are combined to for TBU service brake and for parking brake there is one more workstation is included and apparently the assembly so called parking unit assembly. Then the assembly line of TBU is followed by the testing, finishing work, inspection, package and dispatch. There are three variants of products that are assembled in this TBU assembly line, which are as follows
(i) Indian Railways, (ii) Riyadh Metro and (iii) Kochi Metro (KMRL).
As discussed above, the TBU line consists of assembling of two products such as service brakes and parking brakes which are same for all the three variants. The Standard Man Hour (SMH)
for the complete service and parking brake of TBU unit assembly are tabulated as shown below.
For all three variants, the SMH time are found to be same.
The SMH time for the service brake of TBU unit assembly is done with average time study which is tabulated in table 1 as follows.
SL NO TASK SMH (MIN)
1 Housing Assembly 110
2 Shoe Holder Assembly 70
3 Main Assembly 35
4 Testing 45
5 Finishing Work 30
6 Inspection 10
Table 1: SMH time for service brake assembly
The SMH time for the parking brake of TBU unit assembly is done with average time study which is tabulated in table 2 as follows.
SL NO TASK SMH (MIN)
1 Housing Assembly 110
2 Parking Unit Assembly 80
3 Shoe Holder Assembly 70
4 Main Assembly 35
5 Testing 45
6 Finishing Work 30
7 Inspection 10
Table 2: SMH time for parking brake assembly
The current layout of workstations in TBU assembly line is shown in figure 3. It is seen clearly that the assembly line consists of 4 workstations and main assembly fixture where main assembly is done and a test rig. The yellow checked box denotes the bin trolley and KT denotes the Kanban trolley which feeds the parts to all work stations for the TBU assembly line. And there is one big rectangular box denoted by KT near the storage area is the trolley only used for suspension link arm part for the Indian Railways which is used in workstation 1. On the whole, the layout is not well designed and optimized and therefore the company also needs some improvement over this issue.
Figure 3: Current layout of workstations in TBU assembly line
6. Production Lean Tools
Many production lean tools like VSM, 5S and so on helps in to do the possible improvements in the assembly line and are as follows.
6.1 Value Stream Mapping
VSM is the production lean tool to find out the value and non-value activities in the production flow and helps in eliminating the wastes which improves productivity. It is done for only Service TBU assembly.
6.1.1 Current State
The company faces a number of challenges with their current production layout. To enhance their profitable production of TBU line assembly some of the problems need to be identified and then have to be eliminated. The problems are as follow.
• Not standard material handling system
• The customer orders are pushed through the production control system. Further, which results in increase with the lead-times.
• Sometimes parts are not available in stock when the order comes in and has to be ordered from the supplier, further increase with the lead-times.
• There is no proper organization of shop floor. Operators often can’t find the parts needed, and WIP are kept near the shop floor. These WIP occupies more floor space.
6.1.2 Analysis of Current State
The company mainly focus on MHS which has the high impact on productivity growth. And the assembly flow line seems to be push system. There are many inventories before the starting of assembly line and also before inspection, packing and shipping processes. On the whole the waiting time seems to be 1 to almost 3 days. The total lead time for each product is sound to be under 4 days and 17.5 minutes (i.e 0.5 minutes = 30 seconds), while the time for which value is added to the product is found to be 390 minutes. (Note: two operators are working the same assembly process for shoe holder, housing and main assemblies)
6.1.3 Proposed Improvements
As this thesis work is focused more on MHS, the new trolley is advisable to design with kitting of parts in the pallets. And also kitting of child parts that is C class parts are also can be made as kitting type so as to improve productivity which in turn reduces cycle time and also reduces MHS time. The parts stocks will be managed by the production control through the new automatic reorder technology system, with the safety inventory parts that lasts for two working days. Hence, there will be a safety parts which will be on stock that manages till the reorder time. Production control will send orders each morning to all the workstations as earlier and finally the finished products are shipped at the end of 2nd day, so as to manage transportation cost.
6.1.4 Result
On the whole, by the implementation of these proposed improvements the lead time can be reduced nearly 4 days and 17.5 minutes to 1day and 17.5 minutes approximately (i.e 0.5 minutes = 30 seconds). By the implementation of new material handling system, the company gets profit by improving their productivity which shown in the chapter of analysis. By the new MHS, the cycle time can be reduced from 390 minutes to 380 minutes by eliminating few nan- value added activities. The non-value activities which includes the operators walking and searching of parts time and so on.
The current state map and future state map and done successfully using VSM tool in Microsoft Visio and are shown in figures 4 and 5 as follows.
Figure 4: Current state of TBU assembly line (service brake)
PRODUCTION CONTROL SUPPLIERCUSTOMER SHOW HOLDER ASSEMBLYHOUSING ASSEMBLYMAIN ASSEMBLYTESTINGFINISHING WORKINSPECTIONPACKING C/T = 70 MINS AVAILABILITY = 0.95 OPERATORS = 1 MHS TIME = 6 MINS
C/T = 110 MINS AVAILABILITY = 0.90 OPERATORS = 1 MHS TIME = 7 MINS C/T = 35 MINS AVAILABILITY = 0.95 OPERATORS = 1 MHS TIME = 2 MINS C/T = 45 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 30 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 10 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 300 MINS AVAILABILITY = 0.90 OPERATORS = 2
C/T = 180 MINS AVAILABILITY = 0.95 OPERATORS = 3 35 MINS 17.5 MINS
55MINS17.5 MINS22.5 MINS 12 HOURS
15 MINS 1 DAY
5 MINS 1 DAY
150 MINS 4 DAYS 17.5 MINUTES 390 MINS90 MINS 1 DAY 12 HOURS
DAILY SCHEDULE
ORDERS FROM CUSTOMER ORDER
DAILY CUSTOMER ORDERS 1 PIECE
CURRENT STATE MAP 1 DAY2 DAYS2 DAYS
SHIPPING 35 MINS 17.5 MINS
55MINS17.5 MINS22.5 MINS 12 HOURS
15 MINS 1 DAY
5 MINS 1 DAY
150 MINS 4 DAYS 17.5 MINUTES 390 MINS90 MINS 1 DAY 12 HOURS
Figure 5: Future state of TBU assembly line (service brake)
PRODUCTION CONTROL SUPPLIERCUSTOMER SHOW HOLDER ASSEMBLYHOUSING ASSEMBLYMAIN ASSEMBLYTESTINGFINISHING WORKINSPECTIONPACKING C/T = 65 MINS AVAILABILITY = 0.95 OPERATORS = 1 MHS TIME = 1 MINS
C/T = 105 MINS AVAILABILITY = 0.90 OPERATORS = 1 MHS TIME = 2 MINS C/T = 45 MINS AVAILABILITY = 0.95 OPERATORS = 1 MHS TIME = 2 MINS C/T = 45 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 30 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 10 MINS AVAILABILITY = 0.95 OPERATORS = 1 C/T = 300 MINS AVAILABILITY = 0.90 OPERATORS = 2
C/T = 180 MINS AVAILABILITY = 0.95 OPERATORS = 3 32.5 MINS 17.5 MINS
52.5 MINS17.5 MINS22.5 MINS15 MINS5 MINS 1 day 150 MINS 1 DAY 17.5 MINUTES
385 MINUTES90 MINS
DAILY SCHEDULE
ORDERS WHEN REORDER POINT REACHED
DAILY CUSTOMER ORDERS 1 PIECE
FUTURE STATE MAP SHIPPING 1 day 32.5 MINS 17.5 MINS
52.5 MINS17.5 MINS22.5 MINS15 MINS5 MINS 1 day 150 MINS 1 DAY 17.5 MINUTES
385 MINUTES90 MINS
6.2 5S
Yamagar A.C [18] studied about a lean tool 5S and its importance. 5S is a system which helps to reduce waste and optimize productivity through maintaining an clean, safe, standard, organized workplace and helpful to achieve the consistent operational results. The 5S is generally defined as Sort(Seiri), Set in Order(Seiton), Shine (Seiso), Standardize (Seiketsu), and Sustain (Shitsuke), provide a methodology for organizing, cleaning, developing, and sustaining a productive and well organized work environment. 5S encourages workers to improve their work standard and provides them the knowledge in how to reduce waste, downtime, and inventory due to process failure and lack of parts. 5S helps the line to sort and set the process in sequence and use standard procedures and make a clean environment around the workbench and thereby improve the productivity.
6.3 Kaizen
Kitano et al [19] studied about the continuous improvement and explained about its importance in industries. The Japanese word for continuous improvement is mostly termed as kaizen.
Kaizen is most frequently used where there is the essential need for the continuous improvement. From the Japanese work ‘kai’ which means ‘change’ and ‘zen’ means good and on the whole it means to the term known as improvement. Masaaki Imai [20] elaborates that Kaizen is an essential needs required always for the MHS which is the key role for the production growth. There are many kaizen proposals for this assembly line such as improvement with the trolley, also improvement with the workbench, using fixtures for the workstation for easy operation, automatic torque tool can be used and so on.
6.4 Toyota Way 14 Principles
Liker [21] gave the summary on The Toyota Way 14 Principles, in that the principle 6 is more helpful to perform standard trolley and pallet designs in new MHS of this thesis work. Principle 6 -‘Standardized tasks and processes are the foundation for continuous improvement and employee empowerment’. With this help the principle 6 the standard procedure for MHS and standard design of trolley size and pallet size and then it should be documented which will be beneficial for new employees to work easily.
7. Current Material Handling/Feeding System
The material handling/feeding system is very much important for the operators who are working in the assembly line. Also the material handling system plays a vital role in productivity improvement which should be made easy for the operators in performing their jobs. The current material handling system, in which the trolleys are placed is found out to be approximately 2.5 to 3 metres from the the workstation and the bin trolleys are placed in front of the workstation which is easy reach of the operators hands. The parts are categorised into three class such as A, B and C class parts. The A class parts are the painted parts, those are kept in a separate trolley (1 trolley) and B class parts are the parts from the stores, those are kept in another separate trolley (2 trolleys) and finally the child parts know as C class parts are also from the stores, those are kept in bin trolley (2 bin trolleys). The above mentioned parts are not kept according to the particular workstation rather than that they are kept in accordance to A, B and C class parts. Because of this there were confusion in identifying the parts and also it affects the performance and the productivity of the TBU assembly line.
The MHS time study is on average and tabulated as shown in table 3 below. A simple stop watch is used for the study. It is noted visually that picking one part from the trolley and placing it in the workstation, the operator takes approximately 15 to 20 seconds.
Sl No Workstation MHS - time (Trolley) in mins
MHS – time (Bin trolley) in mins
Total MHS time in mins
1 Shoe holder assembly 5 1.2 6.2
2 Housing assembly 4.33 3 7.33
3 Parking Unit assembly 3.67 3 6.67
Table 3: MHS time study
This thesis work helps in designing the trolley according to the specific workstation and also helps in kitting of the parts which helps in improving the performance and the productivity of the TBU assembly line.
7.1 Effects Of Current Material Feeding System
From the data that were collected during thesis work is to analyse the current material feeding system in assembly line. Parts quantity, inventory plans are the very useful data which became easy for analysis. The effects of current material feeding system are described and shown in figure 6 below.
Part Shortages in MHS is defined as the major issue in the assembly line being affected was because of lack of getting right part at right time. This is due to the parameters like, supplier delays, improper inventory control.
Poor Kanban Quantity in MHS is defined as the storage is not managed in the proper balanced condition. Some parts will be stay fixed in the inventory at line side. This tends to waste according to lean production system.
Unstandardized Work in MHS is defined as the parts picking is done manually by the operators, they started collecting parts in batches required for one shift and this affected their standard work procedure which in turn leads to affect the production.
Jimesh M. Gajjar [7] gives the review on material handling system (MHS) in the shop floor.
As continuous supply from stores is being practiced, all parts were loaded and stored at line side such that even few parts were used less frequently. This lead to occupy more shop floor space. This results in time consuming activity for the operators to walk and search for parts required for assembly operation. Therefore, there is no 5s is strictly practiced in the line. This affects the production rate apparently. Also the current MHS is tough to handle by the operators which is also not in the ergonomic way
Figure 6: Effects of current MHS
7.2 Current Trolley
Parts from stores are known as B class parts and parts from the paint shop are known as A, class parts are loaded in the tow different trolleys as shown in the figures 7 and 8 below. These are the parts which are required for all work stations in the TBU assembly line. But unfortunately, the parts are not kept according to the workstation which further tends to make the confusion and searching of parts for the operators to work with. Also, this trolley is not standardized which tends to the lot of time consuming for the production.
EFFECTS OF CURRENT
MHS
NO STANDARD
RULES TO FOLLOW
TOUGH TO HANDLE
NOT ERGONOMIC POOR
KANBAN QUANTITY PARTS
SHORTAGE
Figure 7: Current trolleys for TBU assembly line
Figure 8: Current trolleys for TBU assembly lin
7.3 Current Workbench and Bin trolley
The workbench and the bin trolley for the TBU assembly line is show in figure 9. The workbench is not much ergonomic for the worker to perform their job as there are no fixtures to hold the parts in one position. Also, the tools are kept under the rack below the workbench as shown in figure which is also not ergonomic and tends to time consuming with the handling of these tools. Further, it results in affecting the productivity of the TBU assembly line.
Coming to bin trolleys, the child parts are not kept in the sequence order according to the assembly instruction and they are all meshed up which results in confusion for the operators to work with that leads to time consuming in production and affects the productivity.
Figure 9: Current workbench and bin trolley.
7.4 CAD Modelling
Figure 10: New trolley design for MHS
The new trolley is design shown in figure 10 was designed according to the given constraints.
The constraints for the new trolley design should be designed in such a manner that, one trolley should hold almost all 10 complete assembly parts which are required for the appropriate workstation and the trolley should be more flexible and easy for the operators to handle and perform their job. Also, the cost of the trolley should be very cost effective.
For which the design ends up with a new concept of kitting of the parts and store it in one pallet such that one complete assembly can be done in that particular workstation. Also, the new trolley design can able to hold 12 complete assembly parts. Considering there are 12 numbers
of complete TBU assembly part is required for the one bogie and also the design has meet that requirements successfully. From the above design two assemblies are merged to a single workstation which is shoe holder assembly and suspension/support-arm assembly. The design of the new trolley is of standard size for the three-assembly workstation such as shoe holder assembly, housing assembly and parking unit assembly. Also, the pallet design is of standard size and only the partitions in the pallets are different for different assembly workstation.
The following picture gives the clear pictorial representation of the new trolley design. The design and assembly is done using CatiaV5 and Pro-E Creo software. The new trolley design has 4 racks and in which three pallets can be placed in one rack and totally there will be 12 pallets placed in the trolley. The yellow color pins are known as safety stopper which ensures the pallets to be supported in its place.
7.5 Kitting Concept
The kitting plays an important role in this thesis work which has great impacts on MHS, as the existing MHS of the assembly line is not flexible and it is very time consuming. Hence, the kitting of parts has more advantageous things for the operator as well for the productivity improvement.
In this thesis work, the kitting of parts are made based on the requirement of parts of that specific workstation. Now the both A and B class parts necessary for the assembly of the specific workstation are kitted and placed in the pallets and then the pallets are placed in the appropriate trolleys.
7.6 Palletizing Concept
The pallets are designed in such a way that it holds all the A and B class parts of all three variants mention earlier. The pallets are designed using a software CatiaV5. The pallets also have some design constraints such that it should hold all the parts for one complete assembly for particular workstation. Another constraint is that the pallets should be be designed such that it should hold both the parts of normal train and metro trains, as the size of the parts are
different. For instance, one pallet is designed in a such a manner that it holds all the A and B class parts for that particular workstation and also for both normal trains and metro trains.
The pallets for easy assembly workstation are shown below in figures and apparently the parts that the pallets should holds are tabulated below each figure. Also, the partitions in the pallets have some design constraints, that it should be 3mm thickness minimum.
Shoe Holder Pallet is shown in figure 11 below and the parts that it should hold are listed in the table 4 below as follows.
Figure 11: Shoe holder pallet
SL NO PART NAME QUANTITY
1 Shoe holder part 1
2 Cradle 1
3 Friction spring 1
4 Spindle 1
5 Leaf spring 1
6 Shoe holder cover 1
7 Screws 4
8 Suspension link/Support arm 2
9 Bearing 1 2
10 Bearing 2 2
11 O-ring 4
12 Sleeve 1 1
13 Sleeve 2 1
14 Flexible arm 2
15 Bellow 1
Table 4: Part list for shoe holder pallet
