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Lean Manufacturing Implementation In
PET Preform & Stretch Blow Molding Unit
BITS ZG629T: Dissertation
By
Puneet Khatri
2013HZ79207
Dissertation work carried out at
Novitas Plast Private Limited, Indore (M.P)
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCEPILANI (RAJASTHAN)
November 2015
Lean Manufacturing Implementation In
PET Preform & Stretch Blow Molding Unit
BITS ZG629T: Dissertation
By
Puneet Khatri
2013HZ79207
Dissertation work carried out at
Novitas Plast Private Limited, Indore (M.P)
Submitted in partial fulfillment of M.S. Manufacturing Management Degree Program
Under the Supervision ofRavi Dwivedi and Senior Manager
Novitas Plast Private Limited, Indore
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCEPILANI (RAJASTHAN)
November 2015
CERTIFICATE
This is to certify that the Dissertation entitled Lean Manufacturing
Implementation in PET Preform & Stretch Blow Molding Unit submitted by
Puneet Khatri having ID-No. 2013HZ79207 for the partial fulfillment of the
requirements of M.S. Manufacturing Management degree of BITS,
embodies the bonafide work done by him/her under my supervision.
______________________
Signature of the Supervisor
Place: Indore
Date: 29/10/2015 Mr. Ravi Dwivedi (Senior Manager)
Novitas Plast Private Limited, Indore Name, Designation & Organization &Location
Birla Institute of Technology & Science, Pilani
Work-Integrated Learning Programmes Division
First Semester 2015-2016
BITS ZG629T: Dissertation
ABSTRACT
BITS ID No. : 2013HZ79207
NAME OF THE STUDENT : Puneet Khatri
EMAIL ADDRESS : [email protected]
STUDENT’S EMPLOYING : Novitas Plast Private Limited, IndoreORGANIZATION & LOCATION
SUPERVISOR’S NAME : Ravi Dwivedi
SUPERVISOR’S EMPLOYING : Novitas Plast Private Limited, IndoreORGANIZATION & LOCATION
SUPERVISOR’S EMAIL ADDRESS : [email protected]
DISSERTATION TITLE : Lean Manufacturing Implementation In PET Pre-form and stretch blow Molding unit.
Abstract:
Preform Production and Jar manufacturing has always been fast moving, demanding, and challenging business. Due to serious domestic and international competition, margin has become very stringent. Companies manufacturing process is plagued with inefficient practices and lot of wastes (Muda).
Purpose of this project is to investigate overall manufacturing process, analyze improvement opportunities and determine how lean principle can be applied to improve efficiency and making necessary changes.
There are various lean techniques but during project we have focused specially on VSM and SMED implementation. The efforts during making the changes were focused on adopting the SMED and also to reduce defect rate.
Broad Academic Area of Work: Production System Planning and control
Key words SMED, VSM
______________________ ______________________Signature of the Student Signature of the
Supervisor Name: Puneet Khatri Name: Ravi Dwivedi Date: 29/10/2015 Date: 29/10/2015
Place: Indore Place: Indore
ACKNOWLEDGEMENT
I take this opportunity to owe a great many thanks to people who helped and supported me during the accomplishment of this dissertation.
I would like to extend my gratitude and thanks to Mr. Ravi Dwivedi, the supervisor of this project for guiding and helping me out technically during all the phases of this project with attention and care.
He has helped me collecting necessary requirements and channeled my effort to get in touch with correct end-users and take inputs from them. He has taken pain to go through the project and make necessary corrections asand when needed.
I express my deep sense of gratitude to Mr. Milind Raguvanshi the additional examiner of this project for his timely support and technical guidance. He has been a great support while doing testing related to the tool and making it more user friendly interface.
Thanks and appreciation to the helpful people at Novitas Plast Private Limited, Indore for their support. I would also thank my family, friends and well-wishers without whom this project would have been a distant reality. I would like to thank BITS, Pilani for providing me this great opportunity to explore new areas.
Table of contents
Cover Page.........................................................................................
Title Page..................................................................................
Certificate........................................................................................
Abstract.............................................................................
Acknowledgements.....................................................................
Table of contents........................................................................
List of figures....................................................................................
List of tables.............................................................................
Introduction to Study........................................................
Introduction..................................................................................... Problem Statement............................................................. Purpose and Scope of Work......................................................
Theory............................................................................. Womack and Jones Lean manufacturing implementation Model...................................Lean production techniques.......................................................
Value Stream Mapping.................................................................SMED....................................Fish Bone Diagram.........................................................................Overall Equipment Efficiency .............................................................
Pet Technology.............................................................................Injection molding....................................................................Blow Moulding................................................................................
LEAN MANUFACTURING IMPLEMENTAION..........................................................................
Value Stream Mapping of Unit........................................................Mould Setup and SMED...............................Equipment efficiency............................................................Defect Rate...............................................................................
Results and Conclusion..................................................................
Bibliography & References........................................................
LIST OF FIGURES
Sr. No.
Fig. No. Figure Description Page No.
1 Fig.1 Flowchart for applying SMED technique
2 Fig.2 Fishbone Diagram
3 Fig.3 Injection Molding machine
4 Fig.4 Basic process of the Unit
5 Fig.5 Value Stream Mapping Of Novitas Plast Pvt. Unit
6 Fig.6 Machine internal & external setup time
LIST OF TABLES
Sr. No.
Table No. Table Description Page No.
1 Table. 1 Changeover on Injection and Blowing Machine
2 Table. 2 Operator’s Role
3 Table. 3 Procedure of workers
4 Table. 4 Procedure after streamlining
5 Table .5 Inefficiency Chart
Introduction:
To stay in business it is of most important to win hearts of client through prime
quality and cheapest cost of product. The present need of the companies is to
provide high quality item through continuous improvement. However companies
throughout the globe are under great pressure to reduce prices, great
competition and maintaining global quality standards. Thus solution to this
problem can be addressed by Lean production.
Lean manufacturing was developed by Toyota, which simply means to
remove waste (muda) from the production process, by eliminating activities that
do not add any value to products; because such non-value-added activities add
extra bit of costs on the product which is certainly not desirable by customers.
Thus primary goal of lean manufacturing is to reduce all types of waste or non
value added activity through incorporating less inventory, less human effort, less
time to develop product and utilizing less space to become highly responsive to
customer demand, while at the same time producing good quality products in
the most efficient and economical manner.
Many Big companies over the last few decades have implemented lean
manufacturing principles to address the need of being more productive. Since
lean manufacturing has become more and more popular, many papers have
given details of how lean can benefit companies by implementing lean
techniques. They cited many examples of how implementing lean production has
resulted in escalating productivity, by presenting number and values.
Problem statement
The Indian plastics industry made a promising beginning in 1957 with the
production of polystyrene. Thereafter, significant progress has been made, and
the industry has grown and diversified rapidly. The industry spans the country
and hosts more than 2,000 exporters. It employs about 4 million people and
comprises more than 30,000 processing units, 85-90 per cent of which are small
and medium-sized enterprises.
Global Markets are continuously changing and demanding product of best
quality and cheaper cost. In our country, the survival and growth of small scale
industry largely depends on its ability to innovate, improve operational efficiency
and increase productivity.
Many businesses are trying to take up new business initiative, resources
in order to stay active and alive in the new competitive market place. Lean
Manufacturing is one of these initiatives that focus on the cost reduction by
eliminating wastes or non value added activities.
As per the research at Lean Enterprise Research centre (U.K). Mentioned that
for a typical manufacturing unit, the ratio of activity could be broken down as,
Value added activity ( 5%,)
Non-value added activity (waste) up to 60% and
Necessary non-value added activity – 35%.
This advice that up to 60% of the activity at a typical manufacturing company could potentially be eliminated. There are more than 26 lean manufacturing tools. All Lean manufacturing tools are not possible to implement in industry because of limited resources, i.e. finance, infrastructure, work force etc.
Hence lean concept become a lot more initiative and easy to understand when they are traced to the ultimate goal-eliminating waste.
The company production lines were plagued with lots of wastes and inefficiencies and eliminating these wastes could eliminate lots of costs and consequently increase the profit margins. The company had long changeovers (up to 3 hours), high defect rates (4%), low equipment effectiveness (equipment high downtime rate), spacious warehouse to stock manufactured bottles etc. When the profit margin became narrow the company knew that it is time to increase the production productivity to address the financial crisis.
Purpose and Scope of work
Purpose of project is very clear to investigate overall manufacturing process, analyze improvement opportunities and determine how lean principle can be applied to improve efficiency and making necessary change.
Question 1: What were the main sources of inefficiencies and loop holes in process?
Question 2: How could Lean manufacturing practices help to amend these problems?
THEORY
Womack and Jones LP implementation model
LP originates from the Toyota Production System & was introduced to the Western World by Womack and Jones. According to them LP can be viewed as an umbrella term that includes Company culture, Values, Basic Principles, methods, leadership and employee ship.
There are several Lean Production adoption models, the 5 steps by Womack and Jones (2003) is the approach I used in my attempt toward applying at Company AB.
The method suggests five steps toward adopting Lean Production which are as follow:
1. Specify value For specifying the product value, it is essential to rethink about what the actual value of the product is, specifically from the customers‟ point of view. In fact the values are characteristics and reasons that customers buy a product and willing to pay for it, at a specific time.
2. Identify the value stream After identifying the product value, then it is time to find the activities that add those values to the product. The value stream consists of three critical management tasks;
a) Find all the activities in developing new products from concept to the real production.
b) Map the process from taking orders to the final delivery; and c) The last one is the entire process to shape the raw material into the
final product. In above mentioned steps all activities are mapped and it becomes easy to identify value added and non value activities or Muda.
Hence it’s the time to eliminate all the waste and can take some actions regarding it.
3. Flow Now it’s time to create product flow by reducing batch sizes and doing the activities in line. Single-Minute Exchange of Die (SMED) is a central technique to create the flow and to reduce the batch sizes as much as possible. It provides a rapid and efficient way of converting a manufacturing process from running the current product to running the next product.
Still to create a smoother flow it is critical to continually eliminate wastes.
4. Pull After flow, the pull system should be established, to let the products being pulled by the customers. It means instead of producing and keeping the products in the warehouses, we wait for the orders from customers and then as soon as we sell a specific amount we produce the same amount to refill it.
5. Perfection Finally it’s needed continuously to look for wastes and eliminate them from the processes to achieve more perfection.
Lean production techniques
A wide variety of lean practices have been addressed as lean techniques in different literature. However, some of these practices are being addressed in almost all of literature that has studied lean techniques. Twenty six of these techniques have been addressed. Following are the few techniques description:-
Value Stream Mapping:
Value stream mapping is a lean-management method for analyzing the current state and designing a future state for the series of events that take a product or service from its beginning through to the customer. At Toyota, it is known as "material and information flow mapping". It can be applied to nearly any value chain.
Using the following Method:
1. Planning and preparation. Identify the target product family or service. Create a charter, define the problem, set the goals and objectives, and select the mapping team. Socialize the charter with the leadership team.
2. Draw while on the shop floor a current state value stream map, which shows the current steps, delays, and information flows required to deliver the target product or service. This may be a production flow (raw materials to consumer) or a design flow (concept to launch). There are standard symbols for representing supply chain entities.
3. Assess the current state value stream map in terms of creating flow by eliminating waste.
4. Draw a future state value stream map.5. Work toward the future state condition.
Single Minute Exchange of Dies (SMED):
Single Minute Exchange of Dies is one of the many lean production methods for reducing waste in a manufacturing Process. It Enables manufacturing in smaller lots, reduces inventory and improves customer responsiveness. Also provides a rapid and efficient way of converting a manufacturing process from running the current product to running the next product.
Technique includes:
1. Separate Internal from External Setup Operations: Firstly internal and external setup elements needs to be recognized.The activities that just can be carried out while the machine is shutdown are called internal setup elements while the activities that can be accomplished while the machine is running is called external setup elements.
2. Convert Internal to External Setup: It is important to decrease the amount of tasks that have to be accomplished while the machine is shut down. For example: pre-heating mold to reduce the trial time, etc.
3. Standardize Functions, not Shape: Function standardization requires only uniformity in the parts necessary for the parts setup”. For
example by adding a particular thickness of a palate to the edge of the mold can allow using same clamps in different setups.
4. Simplify Internal Setup: To eliminate fasten and unfasten times some functional clamps can be designed that can reduce fastening time to just some moments. For Example, Replace bolts with knobs and levers.
5. Eliminate Adjustments and non essential operations:
Adjustments and trials takes lots of internal setup time therefore, eliminating them can reduce the setup time considerably.
6. Creating Standardized work & mechanization: Mechanization is often necessary in moving big molds and dies. Hydraulic and pneumatic pressure can be applied in this technique to considerably reduce the setup time to few minutes.
Fig.1
Standardization:
It is the documented procedures which includes safe, easy and most efficient way of doing the work we currently know (also includes the time to complete each task). It helps to eliminate waste by consistently applying best practices and forms a baseline for future improvement activities.
When a task is standardized, then it provides the opportunity to measure how changes in the sequence and the way a task is done affect the results; in fact by standardizing tasks we can compare different ways to complete a job and then choose the best one .
Following are the few benefits for standardizing task:-
a) Process stability. ”stability means repeatability”; therefore, it is necessary to achieve a certain level of productivity, quality, cost, lead time and safety daily. Standardization is a valuable help to achieve this aim.
b) Clear stop and start points for each process. By being aware of market demand and consequently Takt time, it is possible to know which cycle time we need and then measure where in the schedule we are; for example whether we are behind or ahead of the plan.
c) Organizational learning. “Standardized work preserves know-how and expertise. For example, if an expert employee leaves the company, we won’t loss his/her experience”.
d) Audit and problem solving. Standardization makes it possible to assess current condition and identify problems.
e) Employee involvement and Poka-Yoke (error proofing). Since the team member develop standardize work, they can also find inexpensive solutions for the error-proofing.
Fishbone diagram
It is also called as Cause-and-effect diagram or Ishikawa diagram. The tool does not specify the root cause of the problem, but it assists to review different possible sources of a problem. Each cause or reason for imperfection is a source of variation. Causes are usually grouped into major categories to identify these sources of variationIt is used to identify improvement opportunities and to assist in reducing
variability and eliminating wastes.
The categories typically include
People: Anyone involved with the process. Methods: How the process is performed and the specific requirements
for doing it, such as policies, procedures, rules, regulations and laws.
Machines: Any equipment, computers, tools, etc. required to accomplish the job.
Materials: Raw materials, parts, pens, paper, etc. used to produce the final product.
Measurements: Data generated from the process that are used to evaluate its quality.
Environment: The conditions, such as location, time, temperature, and culture in which the process operates.
Fig.2
Overall Equipments Effectiveness (OEE)
It is the tool or framework for measuring production performance/loss by measuring values of availability, performance and quality for a given manufacturing process. It helps to provide a benchmark/baseline and a means to track progress in eliminating waste from a manufacturing process. 100 % Overall Equipment effectiveness means perfect production. (Manufacturing only good parts, as fast as possible, with no down time)
Calculations of OEE components:
The first measured term is machines or processes availability. “The availability element of the OEE measure is concerned with the total stoppage time resulting from unscheduled downtime, process set-up and changeovers, and other unplanned stoppages”
The second element which is measured is Performance Efficiency. “This measures the ratio of the actual speed of the equipment to the ideal speed”
Key Performance Indicator (KPI):
Metrics designed to track and encourage progress towards critical goals of
the organization. Strongly promoted KPIs can be extremely powerful
drivers of the behaviors- so it is important to carefully select KPIs that will
drive desired behavior.
Following are the reason for best manufacturing KPIs:
a) They are aligned with top-level strategic goals thus helping to
achieve those goals.
b) They are most effective at exposing and quantifying waste.
c) Readily influenced by plant floor employees so that they can drive
results.
PET bottling technology
PET (Polyethylene Terephthalate) also named PETE is a kind of polyester material for fiber, injection molded parts, as well as blow-molded bottles and jars. PET is supplied by the resin manufacturers in the form of small pellets; each about .05 gm.
Its strength, temperature tolerance and wear-resistance made it an ideal replacement .This PET bottling technology is almost a new technology. We can remember that few years ago almost all beverages‟ packing was done in either glass or aluminum, still some are. But, PET market has overtaken a big share of beverage packing market. The new markets for PET are still introducing, for example some countries going to use PET for alcoholic drinks packing (especially for beers),for mineral water, juice, edible oil, pharmaceuticals, cosmetics etc.
Main advantage of PET are:-
Crystal Clear: - These products look good, pure and healthy. Brilliant glass-clear PET bottles attract attention and presentation of our product.
Pure and Safe:-PET complies with international food contact regulations. These bottles are tough and virtually unbreakable during production, storage and transportation.
Good Barrier and Lightweight:-The low permeability of PET to O2, H2O and CO2 means that it protects and maintains the integrity of products giving in good shelf life. Its lightweight reduce shipping costs, also the
material in the wall is thinner as compared to glass. Hence high strength and low weight PET bottles can be stacked as high as glass.
No Leakage and designed flexible: - Absolute finish integrity is possible because of injection molded neck finish so the absence of weld line in base means no leakage problems. Also it is suitable for all sizes, shapes, neck finishes, designs and colors.
Recyclable: - Used PET bottles can be washed, granulated into flakes and reshaped as PET bottles or can be used as material for strapping, carpeting, fiber filling ,etc. When it is burned it produces CO2 gas and water leaving no toxic residues.
Good resistance & Long Shelf-life: - PET offers best chemical resistance performance of any polymer used in packaging today. It also has excellent shelf-life performance, especially with new higher barrier formulations.
To manufacture PET bottles two main processes are used in consequence. First the raw PET material is formed to a so called Pre-Form, using injection molding process, then the pre-forms are blew in blow molding process.
Injection Molding Process
Injection molding process have generally used in plastic industries since 50’s. The majority of plastic components are formed through this process. In this process the melted raw material (plastic) injected to a mold and the mold cavity forms the components and then after solidifying the plastic component(s), they are ejected from the mold. It is a fast and economical process and is used to produce large numbers of identical items from high precision engineering components to disposable consumer goods.
Injection molding works in following way:
Material granules are fed via a hopper into a heated barrel, which is melted using heater bands and frictional action of a reciprocating screw barrel.
The plastic is then injected through a nozzle into a mould cavity where it cools and hardens to configuration of the cavity.
The mould tool is mounted on a moveable plate, when the part has solidified, the platen opens and the part is ejected out using ejector pins.
Fig.3
The quality of manufactured components highly depends on 4 factors:
1. Quality of injection machine,
2. Quality of injection mold,
3. Plastic raw material quality, and
4. Injection parameters setting (temperatures, pressures, speeds Etc.).
Once the three first factors met quality levels and the fourth factor (parameters) set correctly, the components can be manufactured within the quality boundaries and no operator to be needed to take care of the machine and quality.
Blow molding process
Blow molding is a manufacturing process by which hollow plastic parts are formed. The blow molding process begins with the melting down the plastic and forming it into a parison or a perform formed by injection stretched. The
perform (parison) is a tube like piece of plastic with a hole in one end through which compressed air can be passed.These performs is then clamped into a mold and air is blown into it. The air pressure then expands the plastic in the shape of mold.Blow molds prices are much cheaper compared to injection molds. Thus even small quantities of a bottle can economically cover the mold price.
There are three types of blow molding:-
1. Extrusion blow molding
2. Injection blow molding
3. Injection Stretch blow molding
Here also the quality of manufactured components highly depends on same factors which are mentioned above along with the quality of pre-forms.
Lean Production Implementation
To investigate improvement opportunity on shop floor we prepared value steam map. Furthermore for specific problem we implemented lean principle.
Value Stream Mapping of Unit:
Raw material for Preform manufacturing is Polyethylene Terephthalate (PET) which is produced by few manufacturer in India namely Reliance Petrochemical (RELPET), Indian Oil Corp Ltd (ASPET). Material is usually shipped in truck load of 15-20Tons in packing on 25-30Kg bags or 1100 Kg Jumbo Bag. Material is usually stored in 1 ton Container.
Pet material is Hydroscopic thus prior to processing it need to be de-humidified for 4-6 hours to reduce moisture content below .02%. This is very important step because it one of the most time consuming and product quality highly depends on moisture content in the raw material. Once raw material is dehumidified it is transferred to injection molding machine via vacuum loaders.
Pet resin get melted at 270-280 Degree Celsius through rotating screw and injected into hot runner mold. Moulds have about 4-24 Cavity depending upon shot weight and neck size of pre-form. This means with single shot machine produces 4-24 Preform. Once melted resin enters mould, it is solidified
via chilled water flowing in the mould channel and Preform is dropped on the conveyor. Production cycle time is about 14-30 seconds depending on shot size. Preform are been packed manually in Box cartoon or PP woven bags and stored in the inventory area.
Company sells Preform as well as bottle. Thus few Preform are directly shipped to customer and they blow them in-house while other are blown by company itself. Company produces all standard size products (Used by many customer) thus giving them flexibility to produce them throughout the year. Company usually maintains 3 Days Stock.
On the other hand majority of pre-form are blown into Jars/bottles in semi automatic blowing machine. Thus waiting time highly depends on standard jars or customized jar. Standard jars are used by many customers while customized jar are made for specific customer. Another problem to be noted is injection molding machine has higher production capacity thus waiting time increases before it’s been blown into jar.
Fig.4 describe the overall basic process of the Unit
Fig.5 Value Stream Mapping Of Novitas Plast Pvt. Unit
After accomplishing Value Stream Maps, few sources of inefficiencies were identified. They were as follows:
1. Mould Setup2. Equipment efficiencies 3. Defect rate
Mould Setup and SMED:
Major inefficiency of company’s production was frequent changeover of mold. Usually changeover time last 2-3 Hours. In many moulds core half needed to be changed, for which mould had to be taken off the machine and then core half are replaced. This is time consuming as operator has to manually pull core out of the mould and another half has to be replaced.
After installing new mold on machine, the process also required to be adjusted in order to have a smooth production process and meet quality specifications. These parameters were injection speed, barrel temperatures and
pressures, on different segments of the machine. These process parameters were adjusted by experience, regarding the product, mold, raw material and injection machine, by an operator.
Changeover procedure for blow molding and injection molding machine were totally different with their individual challenges. Operator spend long hours in setting parameters on machines control panel to produce standard specification product without any defects.
To address this problem I suggested SMED. We prepared process improvement plans and studied overall mold changeover method in-depth. During initial period operator and helper were taught basic of lean manufacturing and introduced to concept of SMED. Some training sessions were been organized during end of shifts. Implementing SMED:
Preliminary stageDuring this stage of project we made in-depth study of the current setup
of process, identifying every movement of machine and tools. It is necessary to know the process, the variability and the cause(s) that produce this variability.
In order to specify the internal and external changeover elements at Company let first look at the procedure of a changeover, on an injection molding machine. The first action the machine operators did was to turn off the machine once the order was completed; then the operator run to the production manager to coordinate the new order details and to complete some paperwork; after getting the new batch order details, he transferred the new molds and auxiliary equipments to the station, where the changeover is supposed to carry out. The previous batch mold was unloaded and the new mold was installed. After installing the new mold, raw materials were transferred to the feeding station
and the machine was adjusted with the process parameters and finally the trial processing take place.
For typical mold changeover, there is requirement of two workers for individual task. After analysis we enlisted task person by individual.
Separating internal and external setup
The first stage consists of separating the operations that should be carried out when the machine is still processing the previous lot (external setup) and those where it is necessary to carry out setup with the machine stopped (internal setup).
The goal for this stage is to separate/classify setup operations according to the given definition of external and internal setup. This classification takes into account the same operations and duration included in the current method, that is to say, without improving any particular operation. First, this seems obvious,
but it is always worth explaining to the worker that the necessary tools for the setup changeover and the new die should be prepared beforehand so that production time can be gained. In practice, it is not unusual for the external activities to begin until after a batch has been completed. The main reason for this is that time to get the necessary tools and materials are not allocated to the operator while he/she is overseeing production operations.
In this stage, the largest SMED cost gains are achieved. It is not unusual to reduce the exchange time by as much as 60%, in some cases, without any capital investments.
In Stage 2, we are Converting internal setup to external setup
The setup process time reduction from the first stage can be very significant but is not where SMED ends. To reduce setup time as far as possible (or economical), it is necessary to study the possibility of converting some internal setup operations into external setup, so that they could be carried out while theMachine is running.
Fig.6 Setup time of machine internal & external setup’s
It is necessary to distinguish the case in where the investment is necessary in spite of the economics. That is to say, in the case where a company could lose an important customer if delivery time cannot be reduced.
In order to decide on an alternative’s viability, it is not only necessary to analyze the economics, but one should also study the new process or system reliability; the possible appearance of new operations (both internal and external) that increase the setup time; and of course, the benefits and possible risks of the new process.
The development of this stage can achieve, in some cases, setup process time nearing single minutes (< 10 minutes).
Stage 3. Consist of streamlining all aspects of the setup process.
This stage tries to improve all the setup operations, both internal and external, reducing their duration or even, if it is possible, trying to eliminate some operations.
Further improvements are possible when the elements of the setup times are recognized. For example, the process parameters can be inputted into the machines controlling system and memory while the mold is installing on the machine, which requires doing the setup in team; or for example if records of the
previous production process parameters were in hand, the trial production could be shorten and the first work of piece of the batch could meet the quality levels.
Capacity, the potential problem: One reason the Company manager and employees were not concern much about their long setup times, was that they had excess capacity; therefore, they didn’t feel urgent to put effort on reducing their setup times. The sense of urgency is critical to create change in routines, and it has been mentioned as the first step in creating any change (Kotter, 1995). However, the SMED is not just about increasing production capacity, and it has been invented at the beginning to reduce the production lot sizes. Shows that increase in capacity is just one of the advantages of SMED. .
High defects rates
The last inefficiency in process is higher rate of rejection and defects. Rejection not only disturbs production but also reduce profit margins. As per our analysis I have enlisted few major causes of higher rejection rate:-
Non-Stable Process: Lack of standardization was major cause of problem on the shop floor. Each time Mold was installed, all process data need to be adjusted as per experience and there was always situation in which some parameter didn’t get correctly adjusted causing lot of rejection and production loss. Thus it is critical to standardize the production process to eliminate the risk to any mistake in setting process parameter. And basic of statistical Process control suggest that before any
improvement in process we need to limit the variations which can only be achieved via process standardization.
Weak Maintenance: Due to lack of any specific maintenance plan, there was regular breakdown of machinery. Employee need to be motivated to perform preventive maintenance and machines health need to be monitored on regular basis. This is very important for production point of view because a single defect in pre-form, which couldn’t be indentified until its blown would cost heavily. Example if 1 of 4 cavities is producing defected pre-form, till the time of Identification Company would have produced more than 25% of defective product. And it will be very difficult to separate defective piece from entire lot. There is definite need for a more scheduled and tougher maintenance was fundamental to keep the equipment in good condition.
Lack of data from previous production runs: In order to start with reducing defects at Company, I have focused on highest rejection rate product, its percentage was as high as 4-5% and company has monthly sale of 15 Tones of the product. There were different kind of defects found in product like burn mark, shrinkage; water mark etc. since company didn’t had any records to each defect. It was really had to differentiate and analyze the root cause of yearly defect.
Furthermore, the detailed records from production history are essential to map how the figures have changed after any action. It is not possible to distinguish if a change in routines or procedure has improved the performance once we do not know how the performance (i.e. figures, defect rates and etc.) has been before the action.
Lack of periodical controlling: As it is very difficult to check all of the manufactured products to ensure that they have met our quality levels, like others, our company also maintains a schedule of checking the quality of products periodically. Initially at Company the manufactured products were supposed to be investigated every 3-4 hours by operators. But many times operators don’t do the task properly.For Example, Imagine for a 48 cavity mold which manufacture’s 48 Pre-forms in each injection (every 30 second), if a quality problem occur, in 4 hours 23,000 defected Pre-forms could be manufactured. Maybe instead
of regular coffee breaks, they were better to plan a more regular quality check/inspection.
Other sources of defects:
Molds :- Since the hot material is injected into the molds and also the mold’s halves open and close repeatedly, under high hydraulic pressure, mold depreciate over time and therefore, some components require to be replaced regularly (e.g. the mold cavities). The maintenance plan specifies how frequent each component should be replaced.
Raw material: - Initially we need to select, the right grade of the plastic material for a specific product with a specific application and process. Secondly, the material should be stocked and preserved under certain circumstances (e.g. warehouse air moisture content should be below some defined levels). Finally, the material should be dehydrated properly right before being processed with injection machine.
Injection machines: - If the process parameters in the machines were not set properly then they will produce products which will not meet our quality specifications. These parameters can highly be different for different products, materials and molds (e.g. temperatures, speeds, pressures and etc.).
Results and Conclusion
Research Question 1: What were the main sources of inefficiencies?
We have identified few major sources of inefficiencies in company. After reviewing VSM we have prioritized these factors on the basis of magnitude (Time), energy and money wasted in the process. We have categorized each inefficiency in three categories namely high, medium and low. Total score is product of impact and ease of solution.
Table.5 Inefficiency Chart
It should be noticed that many other wastes at company were linked to the above items; and if they could be improved the above inefficiencies, then we could have eliminated some of other wastes too. For example, excess inventory and overproduction was mainly because of the long production lead times. And the long production lead times can be reduced by reducing setup and downtimes. Another example is that if we can reduce defects rates, then it would be possible to reduce over-processing.
Research Question 2: How could Lean Production practices help to amend problems?As per Analysis lower equipment efficiency, high defect rate, longer setup time and lack of automation were the major sources of ineffective operations. For particular problem we have addressed specific set of lean principles. For Example setup time could be cut down by proper implementation of SMED, by dividing mould changeover operation into
internal and external elements. By converting internal elements into external elements which provided uninterrupted series of operation which considerably reducing molds setup time. Since company has mould changeover every 36hour, thus via implementation of SMED changeover time has been cut down by 80 Minutes each time.
Per changeover time saved 20min.Annual Time saved = 325*24*80/36 = *4*72Hours= 12 Days.Thus on annual basis 12 days production can be improved with smarter implementation of SMED.
Work Standardization allowed operating with consistency throughout the day. Preparation of Standard operating procedure gave employee better understanding of process and importance of Safety. We maintained Process record from last standard working of mold which helped to reduce rejection rate as there was no hit and trail method adopted to set process parameter.Rejection rate for First 2 Hour of Working was about 3-4%, By using proper process parameter this rejection rate was cut down to 2-2.5%.
Equipment availability could be improved by identifying the root cause of the errors in production lines. The defect rates could be reduced by implementing a quality control process, which periodically checks the quality of the manufactured products, and documents the quality records to use them in statistical tools for further improvement strategies. We have developed few preventive maintenance plans which we have implemented on shop floor, buts it is very tough to stop 4-5hours of production to perform maintenance. New sets of quality testing equipments have been introduced to have completed monitoring of performs during production.
Bibliography and References1. Shingo, S., 1985, A Revolution in Manufacturing: The SMED System.
Stamford, Conn., Productivity Press.2. Lukas et al. “Lean implementation in a low volume manufacturing
environment: A case study” Proceedings Industrial Engineering Research Conference (2010)
3. Chakraborty et al. “Internal obstacles to quality for small scale enterprises”’, International Journal of Exclusive management research, vol. 1, no. 1, pp. 1-9, 2011.
4. GREEN, L. (2004) Implementation of Lean manufacturing in a small sized company. California State University Dominguez Hills.
5. WOMACK, J. P. & JONES, D. T. (2003) Lean Thinking: Banish waste and create wealth in your corporation, New York, Simon & Schuster.
6. ACHANGA, P., SHEHAB, E., ROY, R., NELDER, G. (2005) Critical success factors for lean implementation within SMEs. Journal of Manufacturing Technology Management, Vol. 17, 460-471.
7. Culley, S.J., Owen G.W., 2003, Sustaining Changeover Improvement. Proceedings of the Institution of Mechanical Engineers, Part B: Journalof Engineering Manufacture, 217/10: 1455-1470.
8. ROTHER, M. & SHOOK, J. (1998) Learning to see: Value stream mapping to create value and eliminate muda, Brookline, Massachusetts, USA, The Lean Enterprise Institute.
9. EMILIANI, M. L. (1998) Lean behaviors. Management Decision, Vol. 36, 615-631.
10.Shigeo Shingo, A Revolution in Manufacturing: The SMED system. Portland: Productivity Press Inc, 1985.
Checklist of items for the Final Dissertation Report
1. Is the final report neatly formatted with all the elements required for a technical Report?
Yes / No
2. Is the Cover page in proper format as given in Annexure A? Yes / No 3. Is the Title page (Inner cover page) in proper format? Yes / No 4. (a) Is the Certificate from the Supervisor in proper format?
(b) Has it been signed by the Supervisor? Yes / NoYes / No
5. Is the Abstract included in the report properly written within one page? Have the technical keywords been specified properly?
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descriptive, precise and must reflect scope of the actual work done. Uncommon abbreviations / Acronyms should not be used in the title
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7. Have you included the List of abbreviations / Acronyms? Yes / No8. Does the Report contain a summary of the literature survey? Yes / No 9. Does the Table of Contents include page numbers? Yes / No
(i). Are the Pages numbered properly? (Ch. 1 should start on Page # 1) (ii). Are the Figures numbered properly? (Figure Numbers and Figure
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