CHAPTER 01 INTRODUCTION At the outset of the project report, the general introduction of the poly bag manufacturing system and the essential facts of industrial collaborator for better understanding of the research project are briefly given in the first chapter. 1.1 Introduction to the Research Project Poly bag products are indispensable in day-to-day life. The film blowing plays a major role in manufacturing of the poly bag products. Film blowing is largely deployed to manufacture poly bags in a continuous flow. The material prices skyrocket to new heights and forecasters see no end to this trend. Also legal restrictions have imposed to some types of polythene products. Under these circumstances, any positive contribution in the poly bag manufacturing value chain is vital to face the challenges of poly bag manufacturing. High density polyethylene (HDPE), low density polyethylene (LDPE), and polypropylene (PP) are basically used as raw materials for poly bag manufacturing process and subsequently undergo some other processes such as cutting, sealing, printing, quality checking, and packing. Due to the variations of parameters in poly bag making process with different products, a considerable setting time as well as a substantial amount of raw material is wasted. Material wastage is 10% to 12% in figures. Rather high lead-time, improper line balancing, and improper inventory control mimic serious bottlenecks in a poly bag manufacturing system from performance point of view. Fluctuation of raw material prices aggravates this current inventory control practice. 1
With the purpose of improving the productivity and the efficiency of the poly bag manufacturing, risk and bottleneck analysis have been carried out in poly bag manufacturing system as a preliminary study for simulation. Further, a simulation has been carried out for the poly bag manufacturing system to further investigate draw backs of the system quantitatively, to propose suggestions to improve the productivity of the system, and to overcome existing challenges. A Graphical User Interface (GUI) is developed to run and present the results of simulation in much user friendly manner. 1.2 Introduction to the Factory The research project is carried out with the industrial collaboration of Thermo Plastics (Pvt) Ltd [1]. The company that sits within the highly diversified umbrella of the BAM group of companies [2], a renowned manufacturing conglomerate that has over decades, maintained a synergy of principles, ideals, and values woven into the fabric of quality, commitment, and dedication for the advancement and development of the group, thereby uplifting and enhancing the quality of life among the people of the nation. The BAM group, an established and highly reputed garment manufacturer and exporter, diversified into various strata of manufacturing, in the industrial boom that took place in the mid-1980s. The boom in Sri Lanka's apparel manufacturing trade brought with it a plethora of accessorized industries, established to consolidate and buoy this multimillion rupee industry in the country. The growth of support industries heralded the beginning of operations for Thermo Plastics (Pvt) Ltd, which was set up in 1985 as a backwards integration company. The biggest asset of the company, pride and joy is skilled Thermo Plastics Team, whose untiring and dedicated commitment to excellence has been the cornerstone of 2
its success. This strives to keep its team continuously competitive, initiating training and development programs, and workshops which include the precepts of quality awareness, productivity, competitiveness and new management, and work tools used in the industry, within the sphere of self motivation and total career advancement. 1.2.1 Mission The mission of the company is "To delight the customers by exceeding their expectations and achieve the highest quality in the products and services offered". 1.2.2 Vision and Objectives of Industrial Partner "To be the most sought after flexible packaging manufacturer within the export apparel sector in Sri Lanka is the vision. The objectives of the company are stated as follows: 1. To be on par with technological advancements within the industry and automate the manufacturing base through an information technology driven policy. 2. To safeguard the environment by adopting ecologically friendly manufacturing technology. 1.3 Production Capacity Present capacity of the company is; 1. Polypropylene (PP) - 500 metric tons per annum 2. Low Density Polyethylene - 2000 metric tons per annum 3. Bag making in side welded and top & bottom welded 4. Bags with gusseted, adhesive tapes, perforation, and with air holes 3
1.3.1 Types of Products The factory is manufacturing few types of poly bags: top seal poly bags, bottom seal poly bags, straight hanger poly bags, angular hanger poly bags, envelope bags, pillow case type poly bags, perforated bags, and bags with ventilation holes. Sizes of poly bags, lengths of printing and types of poly bags are tabulated in Table 1.1 and Table 1.2, respectively. Table 1.1: Poly bag film sizes Polypropylene Polyethylene Minimum film size Maximum film size Average output per month (25 days) Minimum film size Maximum film size Average output per month (25 days) 06 inches 32 inches 37 metric tons 04 inches 47 inches 125 metric tons Table 1.2: Printing lengths Maximum printing length (single print - 06 Colours) Maximum printing length (single print - 02 Colours) 30 inches 50 inches Various types of polyethylene and polypropylene are basically used as raw materials for the poly bag manufacturing. Fig. 1.1 shows a simplified schematic diagram of film blowing process [3], [4]. 4
Fig. 1.1 Simplified film blowing process 1.4 Divisions of Poly Bag Manufacturing System The system consists of five divisions: film blowing, printing, bag making, quality checking and packaging, and administration. Here administrative division is not highlighted, since it is not within the scope of investigation. The simplified process flow diagram of the system is shown in Fig. 1.2. From the process flow diagram it can be identified the sequence of steps in the production process and the storage in work-in-progress (WIP). Detailed process flow diagram of the system of interest is annexed in Appendix - A. Fig. 1.2 Simplified production process flow diagram 5
1.4.1 Film Blowing Division Film blowing which is the initial process of poly bag manufacturing is carried out with film blowing machines in this division. Polypropylene and polyethylene are the basic materials used to blow the film. In the selected production system, the division has four film blowing machines. Two types of machines are used for film blowing according to the materials used for the process: one type is used for polyethylene and second type is used for polypropylene. Fig. 1.3 shows the film blowing division. Fig. 1.3 Film blowing division 1.4.2 Printing Division The second process of poly bag manufacturing is printing, which is carried out in this division. Two printing machines are used to print the bags in the system. One machine is single colour single side one and other machine has the capability to print both side with two colours. Few snap shots of the printing division are shown in Fig. 1.4. Fig. 1.4 Printing division 6
1.4.3 Bag Making Division Bag making is the process which is carried out after the printing in the bag making division. In this division bags are made by cutting and sealing the film. Strips are attached for some bags according to the requirements of the buyer. Fig. 1.5 shows few cross sections of bag making division. Fig. 1.5 Bag making division 1.4.4 Quality Checking Division The final process of poly bag manufacturing is quality checking and packaging. Quality of the manufactured poly bags are checked in the quality checking division by skilled quality checkers. Visual inspection is used to check the quality of finished product in the selected production system. The poly bags which survive in quality checking are packed according to the requirement of each and every buyer. Fig. 1.6 shows the quality checking and packing division. Fig.1.6 Quality checking division 7
1.5 Factory Layout Fig. 1.7 System layout Fig. 1.7 shows the layout of the selected poly bag manufacturing system. Two production lines are employed to produce the poly bags. Four film blowing machines are used for film blowing. Then, the films are stored until subjected to print. Prior to bag making printed films are stored as WIP. In the bag making process, cutting and sealing are carried out to obtain the finished product. The quality checking and packaging is carried out for the stored finished bags. 8