Cycle Time Reduction in Plastic Industry
Ms. Jayata Chanchlani1*, Dr. I. P. Keswani2
1 M. Tech. Student, Industrial Engineering Department, Ramdeobaba College of Engineering and Management, Nagpur, Maharashtra, India
2Professor, Industrial Engineering Department, Ramdeobaba College of Engineering and Management, Nagpur, Maharashtra, India
*Corresponding Author Email: jayatachanchlani.29@gmail.com
ABSTRACT:
RASSA Pipes Private Limited, deals with the production of PVC pipes, Garden pipes and suction pipes of various sizes. At the same time global competitiveness and cost optimization has been the need of the time to look into seriously. This project is about the productivity improvement by reducing the cycle time of a PVC pipe production process with the help of Simul8 Software. The main objective of this project is to study the existing scenario of the shop floor and to improve the productivity of the plant. There are many techniques used for productivity improvement, still there are no definite techniques to be used. By using Simul8 and process flow observation also the un-needed workstation can be identified and be reduced so that the number of workers needed for each process of the production can be reduced so that the productivity can be improved. Thus adding to the objective of productivity improvement as a result.
KEYWORDS: Simul8 Software, Cycle time.
1. INTRODUCTION:
“RASSA Pipes Private Limited” deals with the production of PVC pipes, Garden pipes and suction pipes of various sizes. The production of different types of pipes such as PVC, Suction, Garden pipes of different sizes and colours are being produced. This manufacturing process includes of raw materials, man power, machine hours, online system etc. At the same time the competitiveness and optimization of time has been the need of today to look into seriously.
Polyvinyl chloride, more correctly but unusually poly (vinyl chloride), commonly abbreviated PVC, is the third-most widely produced synthetic plastic polymer, after polyethylene and polypropylene. PVC comes in two basic forms: rigid (sometimes abbreviated as RPVC) and flexible. The rigid form of PVC is used in construction for pipe and in profile applications such as doors and windows. It is also used for bottles, other non-food packaging, and cards (such as bank or membership cards). It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is also used in plumbing, electrical cable insulation, imitation leather, signage, inflatable products, and many applications where it replaces rubber.
Pure poly (vinyl chloride) is a white, brittle solid. It is insoluble in alcohol but slightly soluble in tetra hydro furan.
1.1 Polyvinyl chloride
1.2 PRODUCTION
Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), as shown.
About 80% of production involves suspension polymerization. Emulsion polymerization accounts for about 12% and bulk polymerization accounts for 8%. Suspension polymerizations affords particles with average diameters of 100–180 μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2 μm. VCM and water are introduced into the reactor and a polymerization initiator, along with other additives. The reaction vessel is pressure tight to contain the VCM. The contents of the reaction vessel are continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is exothermic, and thus requires cooling. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain the suspension.
Once the reaction has run its course, the resulting PVC slurry is degassed and stripped to remove excess VCM, which is recycled. The polymer is then passed through a centrifuge to remove water. The slurry is further dried in a hot air bed, and the resulting powder sieved before storage or pelletization. Normally, the resulting PVC has a VCM content of less than 1 part per million. Other production processes, such as micro-suspension polymerization and emulsion polymerization, produce PVC with smaller particle sizes (10 μm vs. 120–150 μm for suspension PVC) with slightly different properties and with somewhat different sets of applications.
1.3 ADDITIVES TO FINISHED POLYMERS
The product of the polymerization process is unmodified PVC. Before PVC can be made into finished products, it always requires conversion into a compound by the incorporation of additives (but not necessarily all of the following) such as heat stabilizers, UV stabilizers, plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants, biocides, blowing agents and smoke suppressors, and, optionally pigments.[9] The choice of additives used for the PVC finished product is controlled by the cost performance requirements of the end use specification e.g. underground pipe; window frames, intravenous tubing and flooring all have very different ingredients to suit their performance requirements.
2. LITERATURE REVIEW:
Literature review in the area of productivity improvement indicates that basically there are two approaches available for better performance of improvement in process industry. The two approaches are (1) Cycle time reduction approach (2) Taguchi’s method of design of experimentation (D.O.E) approach. The project implements Cycle time reduction method.
Cycle time reduction approach comes under time study. In time study the objective is to reduce the time required for machining by different methods. According to Frederick W. Taylor (1880) [27] they are working on time study by using a stopwatch to study and measure work content with his purpose to define “a fair day’s work.” Among his study is “Taylor Shovelling Experiment” which they studied between 400 and 600 men that using their own shovel from home to moving material from mountains of coal, coke and iron ore in around two mile-long yards. Purposes of Taylor to identify that there have different size of shovels and which shovel was the most efficient. Thus analyzing it using stopwatch the results were fantastic which it reduced time, saving numbers of workers and budgeting for every year. This method involves making direct observation by means of a stop-watch.
(a) Siti Anisah Atan, Yaakub, Rohaizan Ramlaan, Taan Geok Foong have proposed Cycle time can be shortened by reducing activity times that contribute to flow time such as setup, move operation, and inspection time. It also can be reduced by decreasing work-in-process or average number of entities in the system. Since over 80% of cycle time is often spent waiting in storage or queues, elimination of buffers tends to produce the greatest reduction in cycle time.
(b) Toly Chen has analysed Shortening the production cycle time improves the responsiveness to customer demands, and leads to significant profits from yield improvement and cost reduction. Some controllable factors that are influential to the job cycle time are identified. Subsequently, the relationship between the controllable factors and the job cycle time is fitted with a BPN. Based on this relationship, actions to shorten the job cycle time can be planned. The feasibility and effectiveness of an action have to be assessed before it is taken in the practice.
(c) In a Case Study: Cycle Time Reduction and Process Improvement at an Electronics Equipment Manufacturer the author has observed,
i) Elimination of 70% of the tool transfer (waiting) time between departments.
ii) Reduction of the waiting time for operators by 50%.
iii) Reduction of the overall tool cycle time from 37 days to 27 days (27% reduction)
iv) Hemanand K, Amuthuselvan D, Chidambara Raja S, Sundararaja G. (2012)[2] focus attention on reduction of waste. This research work has been carried out as a case study in an automotive industry with the objective of waste reduction. Lean manufacturing concepts are mostly applied in industries where more repetitive human resources are used. In these industries productivity is highly influenced by the efficiency working people with tools or operating equipment. To eliminate waste, it is important to understand exactly what it is and where it exists. The processes add either value or waste to the production of goods. This research aims at improving productivity, increasing revenue of the plant by the reduction of motion wastes. In addition, the design and development of the gravity feeder for the material handling have been done as a value addition to this research work. The collection of data is done by direct observation method. The time study is conducted using stop watch. From the collected data, the problems in the current layout are identified and rectified by redesigning the layout in two aspects. One aspect is reducing the material handling by the design and development of new material gravity feeder which is designed in solid edge V19 and structural analysis is done in Ansys 12. Another aspect is conducting the simulation study to reveal the performance of current layout using WITNESS simulating software. Based on the results, a new layout is proposed and implemented. In this research paper the study of whole layouts is considered. And by making some minor changes in sequencing and operator movement, improvement in productivity is done.
v) A window opening is made between the deburring and inspecting operation which saves time by 30 minutes for 100 parts .The machines are replaced and their orientations are changed for easy transfer of material and for sharing the idle time of the operators with other machines. The modifications in the layout will reduce two operators and increase the utilization of the operators by 11.95%. It saves 640 rupees per shift from the operator’s salary. Hence it saves Rs. 5, 99,040 per year which is a considerable savings in the total revenue. Also the implementation of gravity feeder in between the workstations reduces the motion waste and monotonous efforts of the labors which further enhances the labors’ job satisfaction and goodwill of the organization.
3. About Simul8 Software
Simul8 i.e. Simulation software is a product of Simul8 Corporation used for simulating systems that involve processing of discrete entities at discrete times.
It’s a tool for planning, design, optimization, etc.
Its use to create computer model, which takes into account the real life constraints.
It is concerned with cost, time & inventory.
It helps to give unambiguous, concrete results & proofs on how the designed or optimized production system will actually function.
Construction of simul8 model is not usually based on computer programming or statistical data but on drawing organization schemes.
Wherever in the industry there is a process, simul8 can be applied.
Example: service industry, supply chain, etc.
4. Data Analysis (Block Diagram)
5. Properties
PVC has high hardness and mechanical properties. The mechanical properties enhance with the molecular weight increasing but decrease with the temperature increasing. The mechanical properties of rigid PVC (uPVC) are very good; the elastic modulus can reach 1500-3,000 MPa. The soft PVC (flexible PVC) elastic is 1.5-15 MPa. However, elongation at break is up to 200-450%. PVC friction is ordinary; the static friction factor is 0.4-0.5, and the dynamic friction factor is 0.23.
The heat stability of raw PVC is very poor, so the addition of a heat stabilizer during the process is necessary in order to ensure the product's properties. PVC starts to decompose when the temperature reaches 140 °C, with melting temperature starting around 160 °C. The linear expansion coefficient of rigid PVC is small and has good flame retardancy, the Limiting oxygen index (LOI) being up to 45 or more. The LOI is the minimum concentration of oxygen, expressed as a percentage that will support combustion of a polymer and noting that air has 20% content of oxygen.
PVC is a polymer with good insulation properties, but because of its higher polar nature the electrical insulating property is inferior to non polar polymers such as polyethylene and polypropylene. Since the dielectric constant, dielectric loss tangent value, and volume resistivity are high, the corona resistance is not very good, and it is generally suitable for medium or low voltage and low frequency insulation materials.
6. Applications
PVC's relatively low cost, biological and chemical resistance and workability have resulted in it being used for a wide variety of applications. It is used for sewerage pipes and other pipe applications where cost or vulnerability to corrosion limits the use of metal. With the addition of impact modifiers and stabilizers, it has become a popular material for window and door frames. By adding plasticizers, it can become flexible enough to be used in cabling applications as a wire insulator. It has been used in many other applications. In 2013, about 39.3 million tonnes of PVC were consumed worldwide. PVC demand is forecast to increase at an average annual rate of 3.2% until 2021.
7. CONCLUSION
The current study reflects that the situation in our country is very alarming. For reduction of cycle time in a process flow one can use several techniques such as through Simulation model, Back propagation network, Multi observation Study (MOS), etc. Out of this the best technique applicable for this project was to apply simulation in the process flow of Plastic industry with the help of Simul8 software. Also we found the results like reduction of overall process cycle time from 60 minutes to 54 minutes i.e. 10% reduction.
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Received on 12.04.2015 Accepted on 28.05.2015 © EnggResearch.net All Right Reserved Int. J. Tech. 5(1): Jan.-June 2015; Page 25-29
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