Implementation of Lean Manufacturing Philosophy for Productivity Improvement in Knitwear Manufacturing Company Md.Mohibul Islama, Md. Mosharraf Hossainb* and Md. Ariful Islamb Lean manufacturing is a systematic approach to identify and eliminate wastes of all nonvalue added activities through continuous improvement that is being adopted by world class, high performance firms to produce remarkable results. It is also called as a manufacturing system in which friction is absent. Global competition is forcing companies to improve quality, reduce delivery time and lower cost. The traditional manufacturing way of thinking has been “Cost + Profit = Selling price” but in the competing global environment, customers, more or less influence the selling price of a product. Hence the lean way of thinking is “Selling price – Cost = Profit” Under this redefined scenario, the only way to survive in the market is to decrease cost by eliminating all forms of wastes [1]. Lean focuses seven wastes such as overproduction, inventory, waiting, transportation, motion, over processing and defects [2, 3, 4 ]. It hampers the productivity and quality noticeably. It is possible to figure out these wastes by observing production processes intensively. Lean talks about eliminating of these wastes not people. Lean is a journey for eliminating wastes. It makes the manufacturing system more economical by eliminating the mentioned wastes from the system gradually. It achieves the following such as reduction in cycle time, on time deliveries, reduction in work in process inventory, improve in quality, increase in the availability of machines and reduction in scrap / rework. Eliminating waste also frees up valuable resources, such as capital, human, building and machine resources. In this study a knitwear printing floor is practically observed very intensively then setting the parameters for calculating standard printing time as well as printing efficiency and proposed a cellular layout .It is found that both manpower and the fabric which is to be printed are waited simultaneously though both are available there. This waiting is a big waste of this floor. It consumes high working hour through giving small output. A reciprocating auto run dryer is used in printing process for drying the printed area of the fabric. This auto run dryer moves upon the printed fabric and dries the printed area. It moves minimum two times upon the printed fabric and takes about three minutes to dry where printing standard time for once five to seven seconds only. During this time man and printed fabric both are waited until completion of drying for next print. This waiting kills a great deal of working times. Under this situation for eliminating waste forms as waiting time workstations are divided into small work cells and a hand dryer is proposed. A pilot line is setup there for observing the redesign work layout and observed that this is working better than the current layout and it takes only nine to eleven seconds for drying the printed area. Also Printing efficiency is increased about twice by the proposed layout compare to existing one.

Keywords: Lean Manufacturing, Waste, Cellular layout, Dryer, Printing Efficiency _______________ Md.Mohibul Islam, Comfit Composite Knit Limited,Mirzapur, Tangail, Bangladesh, b

Dr. Md. Mosharraf Hossain *, Corresponding Author, Email : [email protected] b

Md. Ariful Islam , Email: b

Department of Industrial and Production Engineering (IPE), Rajshahi University of Engineering and Technology, Rajshahi 6204, Bangladesh,

1. Introduction The knitwear manufacturing industry is a large and most export oriented field of Bangladesh in terms of output, export and employment. The most export items are Tshirt, Polo shirt, Trousers, Jackets, Sweaters and others. At present these manufacturing industries are earning foreign currency about three quarters of total exports, and the industry is a symbol of the country’s dynamism in the world economy [5]. Spinning, Knitting, Dyeing, Cutting, Printing, Sewing & Finishing sections are available in knitwear manufacturing industries. The export items T-shirt, Polo shirt and Trousers are the outcomes of these sections. The cost of manufacturing of a product is directly depends of these individual sections. The survival competition in term of manufacturing cost versus selling price of these fields is increasing day by day in competitive global market. Today, so the main focus is to improve the productivity so that the cost of manufacturing can be reduced. Hence lean seven wastages such as overproduction, inventory, waiting time, transportation, over movement, over processing and defects must be gradually reduced and finally be eliminated. Because every waste incurs cost directly & indirectly, this ultimately enhanced cost of manufacturing & makes the manufacturing processes inefficient. So it is high time to make the processes waste free and dynamic. It may be possible to reduce any kind of non value added activities from the manufacturing processes. Besides job idleness, machine idleness, manpower idleness must be reduced and eliminated. Any wastage indicates the opportunities of improvement & investment of any section. Printing is one of the most important sectors of knitwear industries. Non value added activities are easily visible in printing processes. To develop this section in this paper first printing parameter is selected to calculate printing standard time as well as printing efficiency and finally a cellular layout is proposed to improve the printing productivity.

2. Problem Statement Comfit Composite Knit Limited is one of the most typical knitwear composite factories in Bangladesh where knitting, dyeing, cutting, printing, sewing & finishing departments are available. Printing is one of the most important departments of this factory. In this process basically there are printer man, layer man, screen cleaner, fabric spreader man, pick up man are available who working together to complete printing process. Rubber, pigment, discharge, high-density ete types of printing are printed here. Sewing section is an internal customer of printing section in this factory. So due to print delay sewing lines are directly hampered. To find out the root causes of printing delay it is found that inconsistent are available in printing processes that are responsible for hampering the higher printing productivity. Printing tables and auto run dryers, printing screens, and rubbers are mainly used in printing process. In this study it is found that both manpower and the fabric which is to be printed are waited simultaneously though both are available there. This waiting is a big waste of this floor. It consumes high working hour through giving small output. A reciprocating auto run dryer is used in printing process for drying the printed area. This auto run dryer moves upon the printing table and provides heat on the printed area. It moves minimum two times upon the printing table and takes about three minutes to dry

where printing standard time for once five to seven seconds only. During this time printer man and work in process printed fabric both are waited until completion of drying for next print. This waiting kills a great deal of working times. It is also noticed that there is no specific time measurement to complete a print. So the production target per hour is fixing on the base on thumb rule. So production capacity is remained unknown to management. Besides over movement is occurring there due to improper line layout that occur physical fatigue of the operators quickly. Work is not properly distributed among the operators. So the printer men and others men are frequently waiting at a time interval. Under this situation for eliminating waste forms as waiting time workstations are divided into small work cells and a hand dryer is proposed. The objectives of this study is to select printing parameters to calculate printing time& efficiency so that production target/hour of any kind of printing is given instead of thumb rule and setting proper layout for higher productivity and eliminating waiting time

3. Mathmatical Model Having particular style of a product size wise breakdown quantity may be different, at the same time print design and print size may also different. It varies the printing time. In the printing process spreading, laying and pick up times are directly dependant on the size of fabric that is to be printed. If the fabric size is large then the spreading, laying & pick up times are relatively large than the medium and small size. But the color impression time and drying time are directly proportional with the size of design to be printed rather than product size. If the size of design is large color impression time and drying time will be large compare to medium and small design. Parameters which are considered for formulating mathematical model to calculate printing standard time are1. 2. 3. 4. 5.

Fabric Spreading time (St) Laying time (Lt) Color impression time (Ct) Drying time (Dt) Pick up time (Pt)

Objective function Printing time P0 = ∑ (St + Lt + Ct + Dt +Pt) subject to St = [ {( /n) * ( /n)/100} + {( /n) * ( /n)/100}* Allowance %] Lt = [ {( /n) * ( /n)/100} + {( /n) * ( /n)/100}* Allowance %] Ct = [ {( /n) * ( /n)/100} + {( /n) * ( /n)/100}* Allowance %]*Fc Dt = [ {( /n) * ( /n)/100} + {( /n) * ( /n)/100}* Allowance %]*Fd Pt = [ {( /n) * ( /n)/100} + {( /n) * ( /n)/100}* Allowance %] St > 0, Lt > 0, Ct > 0, Dt > 0 Pt > 0, n > 0, R > o, Nc > 0, Nd > 0

Where, Xi = Cycle time (min) of ith cycle, n = Number of cycles (such as 25 to 50) Ri = Estimated rating of ith cycle time (rating would be given based on cycle time may be70%, 80%, 90% etc) Fc = Frequency of color impression (may be 1, 2, 3………….20 etc) Fd = Frequency of drying (may be 1, 2, 3……………………..20 etc) Therefore printing production target per hour is determined following Yo = (Mp *1*60*Eff.)/P0 Where, MP = Working manpower, Eff. = Estimated working efficiency %, P0 = Printing time (min) Printing efficiency is determined following Pff =Total earned minutes/Total available minutes Where total earned minutes = Total production quantities (pieces)* Printing time per pieces and total available minutes = Total working manpower* Total working hour*60 min

3.1 CURRENT LAYOUT It is found that four printing tables are used in every printing line. There are different types of colors are impressed to obtain expected shade. Color sequence flows mandatory. Any mistake of color sequence defects occurs that may reject the printed fabric. So every printer man uses single color at a time. When impression of a specific color is needed one more time, after every impression needs to wait for drying the printed area where reciprocating auto run dryer is responsible for drying. When one color impression is finished then second color impression is started by another printer man. This is normal practice in line. As the printing line is consisted with four tables so it takes much time to complete a impression cycle by a printer man by moving the long distance. By this time second printer man eagerly waits until the first color impression is completed. It is visible that others printer men are also wait as the same causes. It is also noticeable that if the first printer man does not impress one more colors then waits until the whole color impression is accomplished and new input coming again. On the other hand it is visible that only initially and finally fabric spreader, layer man, pick up men are worked on the printing table. Recess time they wait. Under this layout internal waiting time is so high hence poor productivity & average printing efficiency is 20% per line. Schematic diagram of current layout is mentioned above.

3.2DISADVANTAGES OF CURRENT LAYOUT a) Operators movement path is quite large b) Large cycle time c) Waiting time very high (specially fabric spreader, layer men and pick up man) d) Concentration area large e) In continuous work flow f) Inflexible auto run dryer.

g) Work distributed in equally h) Poor resources utilization specially operators. Fig.3.1.1: Schematic diagram of current layout

Printer man movement path

Sc

Auto dryer movement path

Print Starting Point

Sc

Table-1

Sc

Auto dryer movement path

Sc

Table-2

Sc

Auto dryer movement path

Sc

Table-3

Sc

Auto dryer movement path

Table-4

Sc Print Finishing Point

3.3PROPOSED LAYOUT

Printer man & Hand dryer user movement path (Left to Right) Print finishing

Sc

Print starting

Printing table

Sc Print finishing

Print starting

Printer man & Hand dryer user movement path (Left to Right)

Cell No: 1 From the current layout it is clear that waiting time is very high in printing process. So it kills the valuable time of the system and hampered the productivity. So the cost of printing is enhanced. To overcome this situation a cellular layout is setup there where two printer men are always fixed for two side of a particular printing table and responsible to impress sequentially all kinds of colors that are required to obtain expected shade. Hand dryer is used instead of auto run dryer to provide heat quickly at the printed area for drying. The operator who uses hand dryer always follows the printer man. So there is no chance both the printer man and hand dryer user to wait for next printing. Normally two hand dryer are used two sides of every table. If the printed area be large then maximum four hand dryer can be used but the printer man is always fixed two per table. Under this redesigned layout fabric spreader , layer men, and pick up men are not needed because screen cleaner(Sc) and hand dryer users now responsible for spreading, laying and pickup the finished printed fabric from the table hence the waiting time is eliminated and concentration area for everyone becomes small so printing productivity and quality is improved. Under this proposed layout average printing efficiency becomes about 40% per line that is twice than existing one. The schematic diagram of proposed layout is mentioned above.

3.4 ADVANTAGES OF PROPOSED LAYOUT Operator’s movement path relatively very small for cellular layout. Low waiting time and process dynamism enhance Reduce cycle time Continuous work flow High resource utilization Concentration area relatively very small so quality improve Flexible hand dryer Working environment relatively low heated for instantaneous on/ off system in hand dryer i) Finally brings competitive working environment that improve productivity a) b) c) d) e) f) g) h)

4. RESULT The proposed process compared with existing process it is acknowledged that proposed printing process is really better and printing efficiency is improved about twice than the current one. It gives the signal that productivity and capacity utilization is really enhanced by this process. That means it brings the dynamism in printing process by eliminating non value added activities. So undoubtedly it is spoken that under this system cost of printing will relatively reduce than existing one.

5. Conclusion Now a day, it is really a great challenge for the knitwear manufacturer of Bangladesh to manufacture the knitwear garment economically facing varieties risks. There may be printing section of every knitwear factory. As knitwear manufacturing Industry is mostly based on the human performance and little chance to develop the technical aspect. For this reason time is the major constraint to utilize the workforce with limited resources. This problem may be alleviated by following a better production process. In this case lean manufacturing philosophy is noble idea and implementation of this philosophy is working well. The essence of this study is recommended that this approach is working well in Comfit Composite Knit Limited and should be fully practice at their factory and may be suggested to other knitwear manufacturing industries of Bangladesh.

References Panneerselvam R., (2006), “Production and Operations Management”2nd edition Prentice Hall of India Jeffrey K. Liker and David Meier (28thSeptember 2005) “The Toyota Way” McGraw-Hill Company Book Jeffrey K. Liker and Thomas Lamb ( 26th June, 2000) “Lean Manufacturing Principles Guide” Version 0.5 Aza Badurdeen (2007), “ Lean Manufacturing Basics” Uddin M. S. and Jahed M. A., (2007), “Garments Industry: A Prime Mover of the Socio Economic Development of Bangladesh” An International Journal Of The Cost And Management, vol. 35, no. 1, pp. 59-70.