Reconfigurable Manufacturing Systems

Reconfigurable Manufacturing Systems (RMS) are innovative production systems designed to rapidly adjust their structure, hardware, and software components in response to changing market demands. These systems allow manufacturers to increase or decrease production capacity and adapt functionalities to produce new products or variations within existing product families. Key characteristics of RMS include modularity, integrability, convertibility, diagnosability, and customization, which collectively enhance flexibility and responsiveness. As the global marketplace continues to evolve, manufacturing organizations face increasing pressures to innovate and respond swiftly to consumer preferences. Traditional manufacturing paradigms often fall short under these dynamic conditions, necessitating a shift toward more adaptable systems like RMS. Research efforts are being made across various industrialized nations to refine the design and implementation of these systems, employing methodologies such as the Analytical Hierarchical Process and Virtual Production Systems. By adopting RMS, manufacturers can not only meet the current needs of consumers but also position themselves strategically for future challenges in an increasingly competitive landscape.

Published in: 2021

By: Wienclaw, Ruth A.

Subject Terms

Reconfigurable Manufacturing Systems

Manufacturing organizations need to be able to respond both fully and quickly to the demands of today's rapidly changing marketplace. To enable their production facilities to do this, an increasing number of manufacturing organizations are investing in technology for reconfigurable manufacturing systems. These systems are designed from the outset so that their structure, hardware, and software components can be rapidly changed to adjust production capacity in response to changing market needs. Reconfigurable manufacturing systems have five key characteristics: Modularity, integrability, convertibility, diagnosability, and customization. Research into practical ways to approach the designing of reconfigurable manufacturing systems is underway in many industrialized nations. These approaches include the analytical hierarchical process and the virtual production system approach.

The term "globalization" brings with it thoughts of wider marketplaces and greater opportunities. However, on the heels of such thoughts is the concomitant realization of greater competition. This is compounded by the fact that we live in an age where technology affects virtually every aspect of our lives both at home and at the workplace. However, this technology is not static: Technological advances continue to proliferate, and businesses must stay abreast -- or even ahead -- of the needs of the marketplace in order to not only offer the goods and services that customers want, but also to be able to provide these goods and services at all. In short, technology not only offers opportunities to businesses but challenges as well.

Changing Demands for Manufacturers

One of the places where this fact is readily seen is in manufacturing companies. Long gone are the days of Henry Ford when one could have a car in any color "as long as it is black." Contemporary customers want options and alternatives. If one company is unwilling or unable to offer it, its competitors typically are. In some cases, this means that an organization needs to expand its product line or offer new services. In other cases, however, this means that an organization needs to be flexible so that it can meet the demands of a changing marketplace and stay ahead of the competition. For an organization that primarily deals in services, this can be a challenging enough situation requiring the reengineering of business processes or changing of a marketing approach. However, in manufacturing organizations where there is a tangible product, this often means not only that the product needs to be changed, but that the equipment used to manufacture it must be changed as well. As the twenty-first century progresses, manufacturing organizations will face increasing challenges including the high frequency introduction of new products and innovations, new product demand and mix, new parts for exiting products, new government regulations, and new process technology. To maintain their competitiveness in this rapidly changing environment, manufacturing organizations will need to be able to respond both fully and quickly to the demands of any of these variables.

Manufacturing Paradigms

There are a number of generic paradigms for traditional and conventional manufacturing systems.

The dedicated manufacturing system is designed for a fixed process technology in stable market conditions. This manufacturing approach allows the company to manufacture a single product.
The flexible manufacturing and cellular manufacturing systems are designed to produce limited product types under predictable market conditions and using an adaptable process.

Classifications

Manufacturing systems are also often categorized broadly into four major classifications: job shops, mass and continuous production facilities, batch production, and traditional cellular manufacturing. Virtual manufacturing (a more recent approach) combines the features of jobs shops and traditional cellular manufacturing. A comparison of some of the aspects of traditional, conventional, and advanced manufacturing systems is shown in Table 1.

Manufacturing Systems Aspect Traditional Manufacturing Systems (e.g., dedicated systems) Conventional Manufacturing Systems (e.g., cellular and flexible systems) Advanced Manufacturing Systems (e.g., reconfigurable systems) Process technology over time Fixed Needs to be adaptable to market Should be responsive to market Market Stable Predictable Uncertain Manufacturing policy Pushing Pulling Customizing The gap level between manufacturing systems and demand variations (present/future) high/very high Medium/high Low/very low (expected)

Reconfigurable Manufacturing Systems

Because of the changing demands of the marketplace, an increasing number of manufacturing organizations are investing in technology for reconfigurable manufacturing systems that are designed from the outset so that their structure, hardware, and software components can be rapidly changed to adjust production capacity in response to new market circumstances or alter their functionality to produce a new part of the same part family. Using this philosophy, manufacturing systems will be able to provide organizations with exactly the functionality and capacity needed, exactly when it is needed in response to such rapidly evolving circumstances as changing product demand, the need to produce a new product on an existing system, or the need to integrate new process technology into an existing system.

Components that might be changed in a reconfigurable manufacturing system include individual machines, conveyors within a system or mechanisms in individual machines, new sensors, or new controller algorithms. An example of a generic reconfigurable manufacturing system is shown in Figure 1. In this example, the initial installation of the system (Figure 1a) includes only the capacity and functionality required for a specific part family. The same system can later be upgraded to meet changing requirements such as production of a new product on the same reconfigurable manufacturing system. As shown in Figure 1b, the system can be upgraded to include a second spindle unit and to include an autonomous vehicle or other requirements. The upgraded system also includes additional machines to accommodate increased production capacity. The factory controller has also been reconfigured to handle the additional equipment.

To be useful, reconfigurable manufacturing systems need to be open ended so that they can be improved or upgraded rather than replaced. This approach to system design enables reconfigurable systems to be flexible both for producing a variety of products and for changing the system itself. One of the keys to building this kind of flexibility into the system is to do so from the onset using a modular design for both the hardware and the software that allows the system to be quickly and reliably rearranged to meet changing requirements.

The Research Center for Reconfigurable Machining Systems

One of the leaders in research on reconfigurable manufacturing systems has been the Engineering Research Center for Reconfigurable Machining Systems at the University of Michigan. The center has worked on the development of a type of evolving factory that is designed using a system that allows for reconfiguration of both controls and machines. The development philosophy for this system has several goals.

First, the system is being designed to reduce lead time and ramp up time for both the new and later reconfigured systems.
Second, the system allows for rapid incremental changes to manufacturing capacity to accommodate changing needs of the marketplace.
Third, the system design allows existing manufacturing systems to be quickly reconfigured to produce new products and parts.
Finally, the system allows new process technology to be integrated into existing production systems.

Characteristics of Reconfigurable Manufacturing

Reconfigurable manufacturing systems have five key characteristics: modularity, integrability, convertibility, diagnosability, and customization. Modularity is required in both the product and process design states to enable the system to produce different product families using common resources related by means of different configurations. A true reconfigurable manufacturing system is rapidly integrated from product to process design and can be rapidly upgraded in process technology to meet new operational requirements. To do this, reconfigurable manufacturing systems replace an existing module with a new module when requirements change and the old configuration is no longer sufficient to meet the demands. In addition, reconfigurable manufacturing systems can be converted to produce new products within a product family or quickly adjusted to produce different predictable or unpredictable capacities.

Applications

Research into practical ways to approach to designing reconfigurable manufacturing systems is underway in many industrialized nations. Two of these approaches -- the analytical hierarchical process and the virtual production system approach -- are discussed in the following sections.

Analytical Hierarchical Process

The analytical hierarchical process is a multicriteria decision-making approach that deconstructs a complex problem into a hierarchy that shows the relative importance of each manufacturing alternative using pairwise comparisons. This approach can be applied to select an optimal plant layout configuration (e.g., group technology, transfer lines, functional layout) vis à vis defined objectives and their preferences. Abdi and Labib (2003) performed a research study utilizing an analytical hierarchical process to deconstruct the decision-making process for determining the relative importance of manufacturing alternatives. Design parameters included both conventional considerations (e.g., cost, quality) as well as newer concerns (e.g., responsiveness). A strategy for a reconfigurable manufacturing system was achieved by making trade-offs between the relevant objectives, criteria, and alternatives. This approach was intended to support management strategies for planning and designing systems over their planning horizons.

Process Steps

Specifically, the approach comprised six steps.

First, the strategic objectives and criteria for the evaluation of the manufacturing system were set.
Second, the decision hierarchy was set that could be used to determine the manufacturing choices that were both feasible and best suited to the nature of the manufacturing system.
Third, the weight (relative importance) of each attribute was determined using the inputs of the organization's upper-level management.
Fourth, the criteria, subscriptions, and alternatives were rated vis à vis the next higher objectives or criteria.
Fifth, the preferred alternatives (i.e., those with the higher ratings) were identified and the solution analyzed with respect to the criteria.
Finally, a strategy was developed to determine the most viable manufacturing systems across the criteria for the appropriate planning horizon. Table 2 shows the strategic design parameters of the analytical hierarchical process model used in the study.

Goal: (Re)Design of a manufacturing system for reconfigurability -- Level 0 Level 1: Planning horizons Level 2: Decision makers Level 3: Objectives Level 4: Criteria Level 5: Alternatives Long Term Plant Manager Responsiveness • Ability to produce a wide variety of product type • To let a new product be produced • To quickly respond to changing demand • Reduction of the lead time of product development (new improved models) Existing Manufacturing System (product lines) (EMS) Medium Term Shop Floor Manager Product Cost • Raw material cost • Process cost (machines, energy, operators) • Indirect cost (production planning, inventory maintenance) Reconfigurable Manufacturing System (RMS) Short Term Manufacturing Designer Product Quality • Quality of raw material • Process quality • Finished goods Hybrid Manufacturing System (EMS + RMS) Inventory • Raw inventory • Work-in-progress inventory • Final product inventory Operators Skills • Motivation • Training • Facilities (dedicated or multipurpose)

Process Success

The resultant model was validated in a case study in an actual manufacturing company that produces a large variety of spare parts for the automotive industry. The existing manufacturing system of the company was based on production lines. In the existing system, each line was dedicated to a particular customer. However, the company found that this approach does not provide the flexibility necessary to respond adequately to changes in product designs. In the past, the company tried to increase flexibility by standardizing similar products of different customers at the design stage in an attempt to maintain the existing system without increasing functionality of the product lines.

The use of the analytical hierarchical process helped management of the company better understand the process needed for future investments in manufacturing technology. The process also provided a realistic method to qualitatively and quantitatively evaluate the various aspects of the system options. The authors attributed the strength of the analytical hierarchical process to its use of multiple periods, actors, and criteria. The analytical hierarchical process approach of dividing a far planning horizon into multiple periods (e.g., short-term, medium-term, long-term) both decreases uncertainty and risk over time and also facilitates analysis of the model from the point of view of the various actors. The model is flexible, although not necessarily applicable to all situations.

Virtual Production Systems

As discussed above, there are a number of traditional and conventional approaches to the design of manufacturing systems. These vary on a number of characteristics, including their flexibility toward a changing market. Of these approaches, mass production and batch production manufacturing systems tend to be fairly inflexible and, therefore, less appropriate to many of the constantly changing products in the twenty-first-century marketplace. Two other conventional approaches -- the job shop and traditional cellular manufacturing system -- do have the potential to meet the demands of a quickly changing marketplace. • Job shops are an approach to manufacturing characterized by irregular material flow patterns, long material handling times, high flexibility, frequent machine set-up times, and low production efficiency. In a job shop, machines are grouped by functions to form departments. Job shops are used to produce a wide variety of products in relatively small volumes.

Traditional cellular manufacturing systems are another approach to manufacturing system design that groups together machines required to produce a family of parts, allowing jobs in the same part family to share machine set-up, thereby reducing overall set-up time for the jobs and reducing travel distance. However, cellular manufacturing also tends to require redundant machines among the various cells.
A cross between these two systems is offered by the virtual manufacturing approach. This is a more recent approach to cellular manufacturing in which the cells are logical rather than physical. Virtual cells are also adaptable and allow the sharing of machines and cells. Because the cells are virtual rather than physical, machines within a virtual cell are not necessarily collocated on the shop floor. Virtual manufacturing combines the features of jobs shops and traditional cellular manufacturing.

Procedure for Adapting to Product Mix Changes

Ko and Egbelu (2004) researched the reconfiguration existing job shop and batch manufacturing systems in order to develop a systematic procedure to adapt operations in response to changes in the product mix. Their research indicated that there are efficiencies to be gained in using the virtual manufacturing system philosophy even when it was not possible to rearrange the shop layout.

To apply the virtual cell approach to an existing system, one must first define the initial job shop and the initial traditional cellular manufacturing configurations including machine locations.
To develop a new product mix, the next step is to form virtual cells and form a transport network.
An appropriate scheduling method is next developed to schedule the jobs through the cells and the machines.
When this has been done, the next step is to compute the total machine set-up time and travel distance for each configuration. This information is used to combine the processing system and network system configurations to form the basis of various possible manufacturing system configurations.
The weighted performance for each configuration is then computed using a distance-to-time conversion factor, and the configuration with the minimum weighted performance is used until a new product mix is launched. At that point, the system is reconfigured using the same steps.

Conclusion

Continuing advances in technology, coupled with the demands of a global marketplace, mean that an organization needs to be flexible in order to quickly adapt to the changing needs of the customer and gain or maintain a competitive advantage. One of the ways that this can be done in manufacturing firms is through the approach of reconfigurable manufacturing systems. These systems are designed so that their structure, hardware, and software components can be rapidly changed to adjust production capacity in response to new market circumstances or alter their functionality to produce a new part of the same part family. This is done through the key characteristics of modularity, integrability, convertibility, diagnosability, and customization. Although research continues to determine better approaches to the design of reconfigurable manufacturing systems, the results to date show this to be a viable approach to meeting the ever-changing needs of the twenty-first-century marketplace.

Terms & Concepts

Analytical Hierarchical Process (AHP): A multicriteria approach to reconfigurable manufacturing systems that breaks down the decision process into a hierarchical sequence that shows the relative importance of each manufacturing alternative using pairwise comparisons.

Batch Production Manufacturing: A flexible manufacturing system that can process a large variety of parts in small to moderate volumes of products ("batches"). Batch production systems are characterized by a large amount of work in process and long production times. Batch production systems lie between job shops and mass production systems. They are most suitable for markets with mature products and stable periodic or seasonal demands.

Business Process: Any of a number of linked activities that transforms an input into the organization into an output that is delivered to the customer. Business processes include management processes, operational processes (e.g., purchasing, manufacturing, marketing), and supporting processes, (accounting, human resources).

Cellular Manufacturing: An approach to manufacturing system design that groups together machines required to produce a family of parts, allowing jobs in the same part family to share machine set-up, thereby reducing overall set-up time for the jobs and reducing travel distance. However, cellular manufacturing also tends to require redundant machines among the various cells.

Competitive Advantage: The ability of a business to outperform its competition on a primary performance goal (e.g., profitability).

Globalization: Globalization is the process of businesses or technologies spreading across the world. This creates an interconnected, global marketplace operating outside constraints of time zone or national boundary. Although globalization means an expanded marketplace, products are typically adapted to fit the specific needs of each locality or culture to which they are marketed.

Innovation: Products or processes that are new or significant improvements over previous products or processes that have already been introduced in the marketplace or used in production.

Job Shop: An approach to manufacturing characterized by irregular material flow patterns, long material handling times, high flexibility, frequent machine set-up times, and low production efficiency. In a job shop, machines are group by functions to form departments. Job shops are used to produce a wide variety of products in relatively small volumes.

Mass Production Manufacturing: A production system characterized by high production volume, low product variety, flow shop layout, relatively smooth material flow pattern, lower material handling, lower machine set-up time, high productivity, and low flexibility. Because of their lack of flexibility, mass production manufacturing systems are unsuitable for use in an environment with a frequently changing product mix.

Planning Horizon: The length of time a plan or model projects into the future.

Reconfigurable Manufacturing System (RMS): A manufacturing system designed so that its structure, hardware, and software components can be rapidly changed to adjust production capacity in response to new market circumstances or to alter their functionality to produce a new part of the same part family.

Risk: The quantifiable probability that a financial investment's actual return will be lower than expected. Higher risks mean both a greater probability of loss and a possibility of greater return on investment.

Strategy: In business, a strategy is a plan of action to help the organization reach its goals and objectives. A good business strategy is based on the rigorous analysis of empirical data, including market needs and trends, competitor capabilities and offerings, and the organization's resources and abilities.

Technology: The application of scientific methods and knowledge to the attainment of industrial or commercial objectives. Technology includes products, processes, and knowledge.

Virtual Manufacturing: An approach to cellular manufacturing in which the cells are logical rather than physical. Virtual cells are also adaptable and allow the sharing of machines and cells. Because the cells are virtual rather than physical, machines within a virtual cell are not necessarily collocated on the shop floor. Virtual manufacturing combines the features of jobs shops and traditional cellular manufacturing.

Bibliography

Abdi, M. R., & Labib, A. W. (2003). A design strategy for reconfigurable manufacturing systems (RMSs) using analytical hierarchical process (AHP): A case study. International Journal of Production Research, 41(10), 2273-2299. Retrieved October 17, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=10149095&site=ehost-live

Cazares, A. (2012). Reconfigurable manufacturing systems. In Production and manufacturing management (pp. 101-106). New Delhi, India: World Technologies. Retrieved December 2, 2013 from EBSCO online database eBook Collection (EBSCOhost). http://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=397557&site=ehost-live

Engineering Research Center for Reconfigurable Machining Systems. (2007). Creating the new manufacturing paradigm -- exactly the functionality and capacity needed, exactly when needed. Retrieved October 18, 2007, from http://www.nsf.gov/pubs/2000/nsf00137/nsf00137l.pdf

Ferreira, P., Reyes, V., & Mestre, J. (2013). A web-based integration procedure for the development of reconfigurable robotic work-cells. International Journal Of Advanced Robotic Systems, 10, 1-9. Retrieved December 2, 2013 from EBSCO online database Business Source Premier. http://search.ebscohost.com/login.aspx?direct=true&db=buh&AN=91531031

Ko, K.-C., & Egbelu, P. J. (2004). Reconfiguration of a job shop to respond to product mix changes based on a virtual production system concept. International Journal of Production Research, 42(22), 4641-4672. Retrieved October 17, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=15440825&site=ehost-live

Malhotra, V., Raj, T., & Arora, A. (2012). Evaluation of barriers affecting reconfigurable manufacturing systems with graph theory and matrix approach. Materials & Manufacturing Processes, 27(1), 88-94. Retrieved December 2, 2013 from EBSCO online database Business Source Premier. http://search.ebscohost.com/login.aspx?direct=true&db=buh&AN=69892539

Reconfigurable Manufacturing Systems

On this Page

Subject Terms

Reconfigurable Manufacturing Systems

Changing Demands for Manufacturers

Manufacturing Paradigms

Classifications

Reconfigurable Manufacturing Systems

The Research Center for Reconfigurable Machining Systems

Characteristics of Reconfigurable Manufacturing

Applications

Analytical Hierarchical Process

Process Steps

Process Success

Virtual Production Systems

Procedure for Adapting to Product Mix Changes

Conclusion

Terms & Concepts

Bibliography

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