Keys for Redesign Industrial Facilities in a Current Productive Environment

Pablo Carrizosa I. Eng1, a *, Oliver Rubio M. M.Sc1,b, Julián Mora O. Eng1,c

and Álvaro Guarín G. PhD 1,d

1Universidad EAFIT - carrera 49 N° 7 Sur – 50 Medellín - Colombia - Suramérica apcarrizo@eafit.edu.co, borubiom@eafit.edu.co, cjmoraor@eafit.edu.co, daguarin@eafit.edu.co

Keywords: Redesign methodologies, Dynamic value stream map, Discrete event simulation, Lean manufacturing, Manufacturing systems, Product lifecycle management

Abstract. Today companies don’t have time and resources availability to stop their production to

evaluate new layout and strategies, unless the results are guaranteed. Developing or redesigning

products, gathering them in a product family and creating product platforms can be expensive tasks

that represent a meaningful outlay for companies if they don’t have the adequate tools in order to

facilitate the work. Thus, it is important to define the most appropriate manufacturing system as

well as the performance of the chain value and the equipment layout in order to achieve an optimal

production with the best quality and the shortest times and production costs. Therefore,

computational tools, validated by working strategies and philosophies as Lean Manufacturing (LM)

and Product Lifecycle Management (PLM) become necessary. After the evaluation of products, the

value chain and the layout, these tools allow the construction of models and simulations as dynamic

Value Stream Map (dynamic VSM), to analyze the actual process functioning or future process

plans and PLM software, to estimate production flows, equipment and human labor requirements

without stopping the normal production activities and providing competitive advantages to the

company.

Introduction

The decision of establishing, modifying, moving or removing work stations in order to improve

the facility’s productivity is quite risky. Thus, they must be strongly supported. For this reason, a

series of steps are proposed, based on existing tools validated in industrial environments, which can

help companies to take decisions in order to achieve the plant’s redesign successfully. First, by

applying LM methods as VSM, the current state of the plant is analyzed in order to propose waste

reduction and upgrades in the facilities. Then, performing the simulation of production flows

through a software of discrete event simulation (DES) designed for PLM systems, allows to

intervene in the redesign of the plant to be able to make modifications to the current model and

evaluate the required improvements within what is known as a dynamic VSM, permitting the

development of a greater amount of analysis, process variations and generating possible scenarios

comparable to each other enabling a more accurate decision making.

The benefits offered by strategies such as Flexible Manufacturing Systems (FMS) and

Reconfigurable Manufacturing Systems (RMS), product families and platforms generation,

modularization processes as well as tools such as Integrated Computer Manufacturing (ICM) allow

to evaluate the best solutions for redesigning the plant whether or not the creation of Manufacturing

Cells (MC), different production lines or other strategies to form layout. A valid table model in

terms of cost and time reduction with an increase in the quality of both products and process is

looked for.

Approach

In order to redesign a facility layout, it is required to start by evaluating and inspecting the

products as well as defining product platforms and families that would provide an optimal

Applied Mechanics and Materials Vols. 752-753 (2015) pp 1312-1319 Submitted: 07.10.2014© (2015) Trans Tech Publications, Switzerland Revised: 04.12.2014doi:10.4028/www.scientific.net/AMM.752-753.1312 Accepted: 29.12.2014

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fabrication process. Manufacturing systems must be considered the starting point in order to

propose a production strategy and implement all the appropriated tools. The aim is to achieve an

adequate layout and resources use. For this, there are simulations technologies and validated tools

as VSM and other applicable LM methods. At the end, it is possible to define a layout by employing

computational tools that allow identifying not only the best work point's position, but also internal

transportation equipment, workers quantity, materials distribution, and much other information that

could be obtained doing an accurate analysis.

Products Evaluation

Redesigning industrial facilities not only must involve the production process. For optimal and

reliable results, products and product groups must be evaluated as well. Some methodological tools

allow the identification of efficiency in the fabrication process and facilitate the redesign decision.

An important example of this are: Design For X (DFX) and Design For Manufacturing and

Assembly (DFMA), where software like Boothroyd and Dewhurst[1] let to evaluate, according to

the projected product quantities, optimal processes and materials for the fabrication. These tools

also allow making a comparative analysis between different design alternatives.

Another important tool, called Design for Variety (DFV), evaluates product platforms families

and identifies which components are more important, reducing the impact of variety in product life

cycle costs [2]. In order to evaluate product families there can be applied the product line

commonality index (PCI). This index shows the possibility that products of the same family could

share parts effectively (modularity) reducing total parts number (multifunctionality) [3]. In DFX

there is a large variety of tools to explore depending on the product and process requirements.

The Production Technologies Research group in EAFIT University performed an academic

exercise where it was proposed to design and fabricate a chess board with all its pieces, which had

to be modular. Thus, all of them were made by several parts and some of these parts were common

for several pieces, Fig 1. For this exercise it was employed the methodology proposed in this

document in order to obtain a product, layout and production in an efficient and successful way.

Design, manufacturing and engineering computer assisted tools (CAD/CAM/CAE) were applied as

they are crucial in both academic and industrial environments nowadays. These tools not only allow

defining the product formally, but also help identifying the type of materials needed and the proper

quantities to produce each piece, as well as calculating resistance and physical characteristics of

each component and fabrication times.

Fig. 1 Modular chess conformation

Applied Mechanics and Materials Vols. 752-753 1313

Adaptable Manufacturing Systems

In the past, manufacturing systems were configured once, for a stable environment. Nowadays

turbulent environments demand facilities a permanent adaptability of their manufacturing systems.

Companies must leave behind old procedures and re-configure their organizations continuously.

Some of the most effective manufacturing systems used in the present are:

Cellular Manufacturing Systems (CMS). A cell is a group of work points, machines and

equipment dedicated to a process, a sub component or a whole product that is progressively

organized for a continuous flow between work stations without time loss. The most important

problem in CMS is the cell establishment according to family parts and machines group. Once this

problem is solved it enables any part to be processed within a cell with minimum interaction with

other cells [4].

Flexible Manufacturing Systems (FMS). The concept of Flexible Manufacture was introduced as

a response of a mass personalization necessity and a greater sensitivity to changes in products,

production technologies and market. The main objective in FMS is to show the cost-effectiveness

relation in manufacturing parts that can change over time, with shorter replacement lapses, in order

to achieve productivity and flexibility simultaneously [5]. The main FMS components are:

computer numerical control (CNC) machines, robots and material handling systems (MHS).

Reconfigurable Manufacturing Systems (RMS). These systems are designed to make fast

changes in the structure, hardware and software components in order to adjust production capacity

and functionality within a product family in a quickly way to respond to an unpredictable market

changes [5]. There are a number of technologies available today to achieve physical and logical

reconfiguration in manufacturing systems, but the implementation of RMS still requires additional

development of specific key technologies [6].

Fig. 2 Machine functional reconfiguration [7]

In the chess exercise, for pieces manufacture, prototyping CNC lathes and mills were used. It

required a CMS with a fluid transit of the parts between workstations and a flexible and

reconfigurable capacity to allow the fabrication of the different kinds of pieces in the same

equipment. Equipment layout, conveyor utilization and storage systems help increasing productivity

and reducing times. Thus, generating a 3D model of the manufacturing cells allow the visualization

of the different work spaces, helping to improve the plant distribution and becoming a base to

further simulations.

Fig. 3 is a render of the didactic production micro plant for chess modular pieces. There are two

main manufacturing cells, each one with a materials rack, the proper CNC machines and

transportation conveyors there is also an assembly line and a side area with computers to simulate

and evaluate the process.

1314 Advanced Engineering and Technology

Fig. 3 Didactic production micro plant for chess modular pieces

Value Stream Map Visualization.

In order to make improvements to the plant, the first thing to do is a process map to identify the

most important issues involved with the manufacture and that are related with time, quantity and

quality when implemented. Lean manufacturing has shown that production processes can be

optimized through highly applicable and simple tools that add value to the process. According to

Ohno [8], "LM is widely considered the major step in the development of products beyond the mass

production of Ford." The theory behind the lean philosophy consists in creating more value with

less. During the last decade, competition among organizations has become a matter of not only

productivity, but also the overall performance of the supply chain [9].

One of those tools are valued maps (VSM) that allow visualization of the current and future

production flows, tracing the waste generated in the processes and drawing the route to identify

opportunities for improvement. A value chain is defined as the group of activities (value and non-

value added) that is employed to produce a product or service, or a combination of both for a client

[10]. These actions consider the flow of information and materials within the global supply chain

[11]. In order to identify the source of the waste, non-value added activities and improvement

opportunities, the value chain must be mapped using tools and systematic techniques such as VSM

[10].

Fig. 4 Value stream map scheme [10]

Applied Mechanics and Materials Vols. 752-753 1315

Process Simulation

Discrete event simulation (DES). If the VSM is the picture of the process, the simulation is the

video. DES programs simulate production flow in a system, tracking state changes in model

components when they occur. Unlike the continuous simulation, where time runs in a continuous

state, in the DES time jumps from one event to the next scheduled event, considering only the

necessary processing times. This stochastic technique is selected due to its capability of dealing

with the uncertainty resulted by customer demand patterns, the variability in operation times and

resources availability in addition to high variance in handling systems [12].

Production flow simulation has several uses as: Creating a realistic virtual model of the process

operation; determining and optimizing processing times; evaluating the influence of errors in the

process; identifying bottlenecks and shutdowns in the production flow; determining labor

requirements; evaluating different layout alternatives; optimizing the sequences at production

orders; improving operation control strategies; comparing different scenarios depending on the

production requirements; validating the process design in the planning process; reducing work in

process (WIP); assessing the impact of capital investment; improving production flow (throughput),

resources utilization and the use of facilities; determining storage buffers capacity, number of

required forklifts and conveyors, schedules and production sequences [13].

According to the Association of German Engineers (VDI) Policy 3633, it is estimated that 20%

of the investment costs are influenced by the results obtained by simulating. A reduction around 2%

and 4% of the investment costs is obtained, and only around 0.5% and 1% of the investment costs

correspond to simulation costs [10].

Simulation Phases. The VDI describes three phases that guide simulation users through production

and logistics.

Fig. 5 Phases for a simulation study according to the Association of German Engineers VDI [13]

Selecting the DES Software. At the time of deciding which simulation software to use, it is

necessary to take into account different factors. There are several options of discrete event

simulation software in the market, some of them are more powerful than others like simul8 and

promodel, both have a quick learning curve and allow running simulations with a very good degree

of complexity. There is also DES software like Dassault Sistems or Siemens, each one of these are

part of a suite pack to work on the Product Lifecycle Management (PLM). PLM represents the

missing link between CAD, digital manufacturing and simulation. It also represents the virtual

1316 Advanced Engineering and Technology

world and the interfaces with the enterprise resource planning system (ERP) supporting the physical

side of modern manufacturing throughout the supply chain [14]. Therefore, a simulation program

associated with a PLM platform enables interaction and information transfer with other programs,

involving all those that are related with the process.

VSM and Simulation. The combination of Value Stream Maps and simulation is a powerful

strategy that is called dynamic VSM. The structure and symbology of the VSM are used in a

simulation program making this analysis more truthful and realistic; in consequence the future

model can be more accurate and really predictable. Within the range of DES software it is possible

to obtain libraries to do dynamic VSM. This software has the necessary LM tools, like kanban or

fifo, to formulate the VSM. In Figure 6 it can be seen a typical structure of VSM in a Siemens plant

simulation.

Performing a dynamic VSM instead of classic VSM, represents benefits like: The ability to

examine various product groups and process variations; a reliable dimensioning of the capacity

requirements of the system; real parameters are determined such as delivery reliability, aggregate

value, delivery times and inventory; dynamic effects such as fluctuations in demand,

malfunctioning machines, shift changes and maintenance of equipment are considered; the

calculation of kanban levels and sizes of containers are based on the dynamic fluctuations;

quantifiable results to compare current and future states.

Fig. 6 Dynamic VSM in plant simulation [15]

Layout Analysis

Once the product structure, manufacturing systems applicable to the process, production flows

and value chain behavior are known, it is necessary to organize the physical space of the plant to

operate in the most optimal way. Arranging the layout of a factory depends on many factors that

must be analyzed. The order of processes to be performed initially determines the layout of the

equipment, manufacturing cells and production lines. There should also be considered the storage,

access routes, employees, carriers, etc. Making changes to the distribution requires strong

arguments due to its impact in terms of time and money. For a successful layout diagnosis, PLM

offers simulation analysis based on the facility plans, even in 3D. It is important to give the program

as much data as possible; the exact trajectory of each piece, the transformation that it suffers,

process and transportation times, location of storage places and shipping area, the devices and

Applied Mechanics and Materials Vols. 752-753 1317

routes to move the parts, etc. All this information allows the software to calculate and produce

reports that facilitate in an enormous way decision making.

In the layout analysis, the typical elements to consider are: Determining manufacturing cells to

manage more effectively the flows, share machinery and perform multiple operations in different

components, generating a cluster matrix; generating a quick view of the flows in general, product

flow diagrams, equipment utilization reports, material flow and handling; timing analysis in

material handling activities; creating routes and schedules for the everyday forklift deliveries

minimizing delivery times; organizing and classifying products in the storage area; packing and

organizing products into containers for shipment, generating a detailed operation report [15].

Fig. 7 Layout simulation in Tecnomatix Factory Flow [15]

Conclusion

The steps, tools and considerations presented in this paper, are the main elements of the path that

nowadays companies should follow in order to redesign or improve the production process. The

facility examination, starting from the product evaluation, considering production strategies,

distribution and use of equipment, and the storage and dispatch; combined with the use of validated

philosophies as successful as Lean Manufacturing, all within the digital environment, offers

amazing possibilities to be assertive in decisions making, enabling to use design and simulation

tools that make work easier and allow significantly reducing time and production costs.

1318 Advanced Engineering and Technology

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