Manufacturing Facility Layout Design andOptimization Using Simulation

S. M. Kadane1 and S. G. Bhatwadekar2

The present paper deals with the design of manufacturing facilities layout with theconsideration of downtime of facilities and space utilization. Facility layout refers to thearrangement of physical facilities such as machines, equipment, tools, furniture etc. insuch a manner so as to have quickest flow of material at the lowest cost and with the leastamount of handling in processing the product from the receipt of raw material to thedelivery of the final product.

Keywords: Facility layout, optimization, ABC analysis, simulation, FLEXSIM.

1. INTRODUCTION

THE plant layout is a very critical part of running an efficient and cost effective business.All work areas, production lines, material storage facilities, etc. should be designed toperform to the highest rate and the corresponding shortest cycle time. When designinga plant layout it is necessary to take into account all the functions within the business.The design must include not only the needs for the present business levels but shouldalso have provisions for future expansion. This is included to avoid frequent and costlychanges to the design as demand increases.

Plant Layout is the physical arrangement of equipment and facilities within a plant.i.e. the grouping of equipment and operations in a factory for the greatest degree ofefficiency. The Plant Layout can be indicated on a floor plan showing the distancesbetween different features of the plant. Optimizing the layout of a plant can improveproductivity, safety and quality of Products. Unnecessary efforts of materials handlingcan be avoided when the Plant Layout is optimized. This is valid for:

1. Distances through which the material has to move2. Distances equipment has to move3. Distances operators have to move4. Types of handling equipment needed5. Energy required to move items against resistance (i.e. gravity).

1 Assistant Professor, 2Associate Professor, Department of Production Engineering, Kolhapur Institute ofTechnology, Kolhapur, Maharashtra, Shivaji University, (1smkadane@gmail.com) (2sgbhatwadekar@rediffmail.com)

International Journal of Advanced Manufacturing SystemsVolume 2 G Number 1 G January-June 2011 G pp. 59-65 © International Science Press

I J A M S

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2. METHODOLOGY FOLLOWED FOR ANALYSIS OF THE PROBLEM

2.1. Raw Material Requirement

Total raw materials are divided according to their weights and this data is used forABC analysis. From this we come to know the importance of each type of material.This data is helpful to decide raw material policy.

2.2. Understanding of Existing Process Sequence

To design an efficient plant layout understanding of process sequence is necessary. Forthis the existing manufacturing processes are studied in sequence. The critical operationsin each process are observed carefully. This will help in redesigning the process sequence.

2.3. Time Study

The time study has to be carried out at each processing stage. It is done manuallyusing a stop watch and readings are recorded in time study sheet. The time studyhelps in finding out the time required for each process in the sequence. This data willbe useful in deciding the capacity planning for a new plant. From the time study wealso come to know the bottlenecking stage.

2.4. Layout Designing and Simulation

After studying the process sequence and the time required for each process, the layoutdesigning is done. The layout is designed by taking into consideration the availablespace, interrelation between two successive departments, the importance of eachprocess and the capacity required to achieve the desired output rate.

After designing the layouts, they are simulated using simulation softwareFLEXSIM. The capacity of each workstation and the bottlenecking locations areunderstand by observing the simulation results. From these results a decision is taken,whether to revise the capacity or not. The revised plant layout is again simulated. Therevision is applied in a progressive manner. After comparing the throughput of eachlayout, the one having maximum throughput rate is selected and is proposed to thecompany for implementation.

3. SIMULATION OF FACILITY LAYOUTS

Simulation means process of testing an existing or new invention for modification oruse by means of a prototype. Plant designers generally have only two choices: eitherphysically change the layout of an existing facility and then measure results, or modelthe system and measure results to develop the final facility design before making changes.Plant layout simulation is a tool that uses data to evaluate a current facility layout andshow potential improvement areas. The same data is then used to objectively evaluatevarious layout alternatives for new construction, additions, and/or re-organizations.

3.1. Need of Simulation

Facility layout problems are rather difficult in terms of analytical modeling. When thenumber of departments is large, the material flow volumes between departments are

MANUFACTURING FACILITY LAYOUT DESIGN AND OPTIMIZATION USING SIMULATION 61

random, and a flexible layout is desired, the problem becomes much more complexand usually intractable analytically. Therefore, simulation has been used as a modelingalternative to determine a good layout among a very large number of alternatives.

4. EXPERIMENTAL DESIGN AND RESULTS

Simulation software is a powerful analysis tool that helps engineers and planners makeintelligent decisions in the design and operation of a system. With the help of simulationsoftware, we can build a 3-dimensional computer model of a real-life system, andthen study that system in either a shorter time frame or for less cost than with theactual system.

The simulation software should have the capabilities so that it can be successfullyused to:

1. Improve equipment utilization.2. Reduce waiting time and queue sizes.3. Allocate resources efficiently.4. Eliminate stock-out problems.5. Minimize negative effects of breakdowns.6. Minimize negative effects of rejects and waste.7. Study alternative investment ideas.8. Determine part throughput times.9. Study cost reduction plans.10. Establish optimum batch sizes and part sequencing.11. Resolve material handling issues.12. Study effect of setup times and tool changeovers.13. Optimize prioritization and dispatching logic for goods and services.

4.1. Simulation of Proposed Plant Layout Using Simulation Software (FLEXSIM)

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4.2. The Simulation Results are as follows

Figure 1 Pie Chart of Queue before Tack

Figure 2 Pie Chart of Full Welding Station

Figure 3 Pie Chart of Tack Welding

MANUFACTURING FACILITY LAYOUT DESIGN AND OPTIMIZATION USING SIMULATION 63

After observing the simulation results we don’t find any stacking of componentsin the queue of full welding and finishing workstations. That means the capacity offull welding and finishing workstations are sufficient.

In the above layout two tack welding workstations are proposed, but by observingthe simulation results of the queue which supplies components to the tack weldingworkstations, it is found that there is a stacking of components. 143 components arejoining the queue and only 32 components are being processed at tack weldingworkstation (i.e. 111 components are to be processed). It indicates that the onlybottlenecking station is tack welding operation. So one more tack welding workstationis introduced to remove bottlenecking and to increase the throughput.

After revision the new plant layout is as follows.

4.3. Revised Plant Layout

Figure 4 Pie Chart of Finishing Station

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4.4. The Simulation Results of Revised Plant Layout are as follows

Figure 5 Pie Chart of Queue before Tack Welding

Figure 6 Pie Chart of Full Welding Station

After observing the simulation results, it is found that the bottlenecking beforetack welding is reduced considerably and throughput rate is also increased.

The same procedure is repeated for three different layouts and they are simulatedusing software. The one which is giving maximum throughput rate is selected forimplementation.

5. CONCLUSION

By observing the simulation results the layout which gives desired throughput ratecan be selected. The simulation provides the data which helps in the decision making

MANUFACTURING FACILITY LAYOUT DESIGN AND OPTIMIZATION USING SIMULATION 65

before costly changes or investments are made. It also maximizes the chances ofsuccessful implementation.

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