Part I is an overview of the Manufacturing Systems Environment project. Part I is organized as follows:
Chapter 1: Introduction to the MSE Project
Chapter 2: Objectives and Scope of the MSE Project
Chapter 3: Project Implementation
1. Introduction to the MSE Project
This chapter provides background information about the SIMA project, and in particular those of its activities which fall under the major subheading of Manufacturing Systems Environment (MSE). The remaining chapters of this document deal exclusively with these activities, which will from here on be referred to collectively, for the sake of brevity, as the MSE Project. Section 1.1 discusses the challenges facing U.S. industry in advanced manufacturing, and the need for a systems approach to the introduction of new technologies. Section 1.2 discusses the potential contribution of manufacturing systems integration--the focus of the MSE project--towards meeting these challenges. Section 1.3 places the MSE project within the wider context of the SIMA program as a whole. Additional background information on MSE and supporting SIMA projects can be found in [1], Technical Program Description Systems Integration for Manufacturing Applications (SIMA).
1.1 The national challenge of advanced manufacturing
To stay competitive in today's manufacturing environment, many companies are introducing advanced technologies, particularly computer-based applications, into their businesses. This is motivated by a belief that advanced technologies such as computer-aided design, manufacturing, and engineering (CAD/CAM/CAE)--combined with effective resource management and improved work force training and education--can greatly improve a company's competitiveness and profitability. There are numerous examples supporting this belief, yet on the other hand many cases exist where the expected benefits of advanced technology have not been realized by industry. Some examples of expectations and how they may go unrealized are shown in the following table:
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So companies today find themselves between Scylla and Charybdis. They must accept either the costs and risks that accompany the introduction of advanced technologies or the risk of being driven out of business by competitors who are using those technologies to reach the market quicker, with better products at lower prices.
Despite the risks, businesses are increasingly choosing to introduce advanced technology. In 1993, for instance, the worldwide market for CAD/CAM/CAE software applications increased 5 percent to $16.5 billion, and it is expected to continue growing strongly.
The potential benefits of applying information-based systems to manufacturing are recognized by the Office of Science and Technology Policy in its August 1994 report Information Infrastructure Technology and Applications (IITA). The report describes advanced manufacturing capabilities needed to support Vice President Gore's National Challenges for the National Information Infrastructure:
"American manufacturers seek to recapture world leadership and respect. The specific technical goals are to exploit lean manufacturing (e.g., greater efficiency and lower cost), flexibility (e.g., variation in production runs to allow for consumer preferences), and agility (e.g., supporting small production runs, rapid retooling, and exploitation of . . . electronic commerce services)."
The report further describes how advanced information technologies might be used in manufacturing:
"In addition, companies will be able to band together to jointly manufacture goods. This will require rapid tailoring and composition of shared information services such as inventory control, work scheduling, and product delivery. Potential machine tool vendors and other manufacturing support companies will be willing to provide simulations of new process-control and planning software to enable companies to test before they buy. In addition, software specialty companies will provide access to powerful computer-aided design tools that are currently too expensive for purchase by small companies. This is economically viable because a small company can access both the software and the human expertise that lies behind it, through coordinated on-line consulting services."
This description clearly identifies key technical elements of advanced manufacturing:
Feasible and cost-effective implementation of these elements will require more than the development of new technologies. The liabilities and risks of these advanced technologies must be reduced by applying a comprehensive systems approach to the integration of new technologies into existing manufacturing systems. To be applicable on a national scale, a systems approach should include:
The MSE project will develop such a systems approach, focusing on advanced information technologies for manufacturing, and will disseminate the results through workshops, training materials, electronic data repositories, and other mechanisms.
1.2 Program background
Background
The National Institute of Standards and Technology (NIST)'s program is part of the multi-agency High Performance Computing and Communications (HPCC) initiative as described in the High Performance Computing Act of 1991 and the Senate bill S.4, "The National Competitiveness Act of 1993." NIST's program for FY 1994 and beyond is included under the Information Infrastructure Technology Applications (IITA) category of the HPCC initiative. The objectives of the program are: (1) to accelerate the development and deployment of HPCC technologies required for the national Information Infrastructure (NII) and (2) to apply and test these technologies in a manufacturing environment. Ultimately, these technologies will radically transform America's manufacturing environment, allowing individual companies to interact electronically as part of a "virtual enterprise" to produce world-class products for the 21st century.
The program will focus on technologies and standards that will improve the systems integration function in manufacturing. NIST will perform appropriate activities in the areas of flexible computer-integrated manufacturing (FCIM) with emphasis on both product data exchange (for manufacturing) and electronic data interchange (for electronic commerce) standards that are part of the overall vision for 21st century manufacturing. The infrastructure technologies being developed will serve as an enabler for such manufacturing paradigms as Agile Manufacturing, Concurrent Engineering, and the Virtual Enterprise. The centerpiece of these activities will be a model facility at NIST, the Advanced Manufacturing Systems and Networking Testbed (AMSANT). Researchers nationwide will use the AMSANT facility to research and develop methods for applying HPCC technology to manufacturing. Besides the technology development, important functions of the program include improving the process for developing the key manufacturing interface standards and providing a technology transfer mechanism for getting the program results to industry.
National Information Infrastructure (NII)
The National Information Infrastructure (NII) is designed to promote a seamless web of communications networks, computers, databases, and consumer electronics that will put vast amounts of information at users' fingertips. Development of the NII can help unleash an information revolution that will change forever the way people live, work, and interact with each other. The NII is the platform of information technology resources upon which industry, government, and academia can integrate their information functions.
The HPCC/IITA initiative supports the key areas of research and development and systems integration to demonstrate prototype solutions to National Challenges starting from the advanced technology level moving through higher level of user capabilities to the ultimate user level in National Challenge projects. The IITA consists of four elements: (1) National Challenges are fundamental applications that have broad and direct impact on the Nation's well-being and competitiveness, (2) Information Infrastructure Services provide the underlying network-capable building blocks upon which the national Challenges can be constructed, (3) Intelligent Interfaces will bridge the gaps between users and the future NII, and (4) System Development and Support Environments will provide the network-based software development tools and environments needed to build the advanced user interfaces and the information-intensive National Challenges themselves.
The NIST program is concerned with one specific National Challenge, Advanced Manufacturing:
Supports work in advancing manufacturing technologies through the use of HPCC capabilities in design, production, planning & quality control, marketing & user services. A key element is the development of the infrastructure necessary to make the process and product information accessible over the information highway to both enterprises and customers. Research areas include concurrent engineering, protocols for electronic exchange of product data, electronic commerce for manufacturing, virtual design technologies, etc.
Implementation of the NII concept for manufacturing will allow such capabilities as: (1) customer to "custom design" products, (2) companies to form alliances needed to produce new products (i.e., Agile Manufacturing), (3) small to medium size companies to interact with large companies for bidding on products (i.e., the Virtual Enterprise), (4) software system brokers to "rent" sophisticated manufacturing systems tools, and (5) rapid access to manufacturing knowledge by the product designers which will enable enterprises to use concurrent engineering practices.
1.3 The benefits of manufacturing systems integration
The MSE project is predicated on the belief that systems integration is key to the effective use of advanced information technology in manufacturing. Integration may help a company in several ways:
Knowledge and information: The quality of the decisions made by a company's managers and engineers depends on their knowledge and judgment, and on the information available to them when making the decisions. Decision-makers need access to accurate and timely information. In modern manufacturing facilities, many decision processes are supported by manufacturing software packages, and different decision-makers use different software packages designed for different functions. However, information transfer between packages is often inadequate or inaccurate. Integration of these packages into systems can significantly improve the availability, consistency and accuracy of the information delivered to the decision-makers and thus enhance the quality of their decisions.
People: The systems approach defines the principal functions of systems and standardizes the form of--and in many cases the access to--the principal information units. This reduces learning time for people who have to deal with multiple systems or new systems. Moreover, systems integration eliminates the need for human involvement in non-value-added activities such as copying, reorganizing, and reinterpreting information passed between different software systems. This releases skilled personnel for the value-added activities that further the interests of the company.
Systems: The systems approach defines the information interactions among all components of the system, so the impact of changes in one component can more easily be evaluated, and the overall system can be adapted to make the best use of new technologies. For example, improving the capability of a machining process without changing the economic models used in tolerance synthesis during product design may simply drive up manufacturing costs for the product. Such problems can be avoided through the use of integrated systems models.
Process management: Integration of design engineering, manufacturing engineering, and production software systems improves the availability of production-related information and constraints to designers, resulting in better design decisions. It also improves the availability of design-related information and constraints to production engineers, resulting in better production decisions. The major saving is in the number of engineering iterations required before production can commence.
Metrics and diagnostics: Systems integration creates the paths by which automated flow of information among systems takes place. This allows (without requiring) automated capture of the timing, source, and content of information transfers without special actions on the part of engineers and managers. Such captured data enable the evaluation of performance metrics for engineering and manufacturing systems. The data also provide valuable support in backtracking and diagnosing problems in the product realization process.
An activity model shown in Figure 1 defines the elements of SIMA's manufacturing model and identifies the major flows of information and controlling functions.
1.4 Overview of the SIMA ProgramDetails of the broad background of the SIMA Program as part of the federal government HPCC initiative were given in the Preface and also in section 1.2. As stated there, all eight NIST laboratories are involved in the program. By the time it is completed, NIST will have developed, tested, validated, and demonstrated multiple integration methods, tools, and technologies for integrating product and process-related activities in the product realization process. The intention is to use commercially available, state-of-the-art software systems wherever possible, and to utilize existing or emerging infrastructure technologies and standards to provide means for the construction of modular, open, reconfigurable, intelligent integrated systems.
The STandard for Exchange of Product model data (STEP: see Chapter 8) is considered to be the key standard for integration activities, although many other interface standards are potentially useful within the program. The STEP effort is expected to accelerate the evolution of concurrent engineering, support electronic commerce, and enable business partners to share sophisticated digital product data as easily as paper drawings are shared today. If it lives up to its promise, STEP will be one of the most influential standards that has ever been developed in the field of industrial automation.
Three major environments have been defined for SIMA program activities. These environments were defined as a result of a joint NIST/Industry workshop on defining systems integration ne eds for manufacturing. The workshop conference report [2] recommendations helped focus the SIMA program activities around three major needs. They include Standards Development needs, Technology Development needs and Technology Transfer needs. The SIMA program followed the workshop recommendations by creating three program environments which focus on the various needs in each area. The program environments are:
Each environment includes projects appropriate to particular NIST roles in support of the HPCC initiative, and addressing the major technology and standards issues outlined in the IITA program report referred to in Section 1.1. As mentioned earlier, the present document covers work performed in the Manufacturing Systems Engineering Environment of SIMA, referred to in what follows as the MSE Project. Both this and the other two major SIMA components are outlined below in order to place the MSE work in its wider context.
1.4.1 The SIMA Manufacturing Systems Environment (MSE)
The major focus areas of MSE are the development of information models, infrastructure technologies and interface protocols to support systems integration, and the application of HPCC to the design, planning and production activities of the product realization cycle. The chosen product domain is that of electromechanical products, though many of the MSE deliverables will have relevance to the integration of manufacturing applications in other domain areas. Little more will be said under this sub-heading, since the MSE scope, domain and methodology are described in detail in the remainder of this report.
1.4.2 The SIMA Standards Development Environment (SDE)
The SDE objectives are:
Within SDE there is a general theme of providing effective support environments for the development of standards as well as facilitating harmonization across a broad spectrum of standards supporting many diverse aspects of enterprise integration.
The following are the primary SDE focus areas:
1.4.3 The SIMA Testbeds and Technology Transfer Environment (TTTE)
The TTTE objectives are as follows:
1.5 Timescale and resources of the MSE project
The MSE project is planned for five years. During that time, it will develop through three distinct phases. Phase I includes analysis of integration problems and design of integration solutions. Phase II includes implementation and testing of integration solutions through prototypes and demonstrations. Phase III includes promotion of results through standards and industry implementations.
During Phase I, lasting two years, the project will gather information on new technologies that support integration, develop information models and interface specifications for a broad spectrum of manufacturing applications, and acquire CAD/CAM/CAE software systems representative of those used by industry. The objective will be to understand current integration limitations and to develop an engineering architecture that defines the technologies and standards to be used in Phase II to support MSE integration demonstrations. Activities in Phase I will allow the examination of integration requirements across a wide range of engineering activities, so that the results will be useful to many sectors of industry.
During Phase II (years 3 and 4) an integrated system will be constructed, and integration solutions will be tested in collaboration with industry through computing and communication facilities provide by the NIST AMSANT (see below). Phase II demonstration activities will be more narrowly focused due to a number of factors, including resource constraints on the range of commercial packages that can be included in the integrated system, the capabilities of those packages, their level of conformance to standards such as STEP (STandard for the Exchange of Product model data), the availability of human resources, and the choice of product domain. The specific domains of interest may be influenced by collaborations with industry.
The third and final phase of the MSE project (year 5) will concentrate on the dissemination of integration solutions developed in Phase II, in order to promote the implementation of these solutions as future standards.
MSE will make use of SIMA's Advanced Manufacturing System and Networking Testbed (AMSANT), which will serve as a site for demonstrations and for testing high-risk technologies and interoperability by industrial technology suppliers and users. AMSANT is a distributed set of testbeds linking the computing resources of researchers at NIST and in industry in order to promote collaborative development of integration solutions. AMSANT will provide high-speed communications, software development tools, information repositories, and physical laboratory space in order to accomplish MSE goals. Researchers from across the United States will use the AMSANT facility to research and develop methods for applying HPCC technology to systems integration problems affecting manufacturing.
1.6 Collaboration and technology transfer
Throughout the MSE project, strong collaborations with industry, other research institutions, and standards organizations will be developed and maintained. Prototype systems and interface specifications will be communicated to appropriate standards organizations. Results will be made available to U.S. industry through workshops, training materials, electronic data repositories, and pre-commercial prototype systems that can be installed by potential vendors for test and evaluation. NIST will distribute standards reference data, technical information, and product designs via digital library technologies.
Figure 1 SIMA Manufacturing Activity Model
The product realization process is defined as:
The process by which new and improved products are conceived, designed, produced, brought to market, and supported. The process includes determining customers' needs, translating these needs into engineering specifications, designing the product as well as its production and support processes, and operating these processes.Improving Engineering Design: Designing for a Competitive Advantage, National Research Council, 1992.
The development of computational aids supporting specific aspects of the overall process has led to what are sometimes called "islands of automation." The MSE project is concerned with building bridges between the islands by integrating specialized software systems that support various parts of the product realization process.
The MSE project will focus on the technical aspects of that process, in the hope that they will be integrated with the more management- and business-oriented aspects in the future. This chapter briefly outlines the activities covered by the MSE project and explains how the product domain and scope of the project were decided.
1 Objectives
The overall objective of the MSE project is to provide industry with open architectures and interface specifications that will facilitate the implementation of CIM (Computer-Integrated Manufacturing) systems built from commercially available software packages.
This will be achieved through the use of a formal systems approach to the specification and implementation of integrated manufacturing systems. A suite of generic models and specifications will be developed for the information and processes within the scope of the MSE project. These will be validated by the implementation and demonstration of one or more integrated systems based on commercially available software.
The models and specifications will provide guidance to software developers and vendors on making their packages easy to integrate within larger heterogeneous systems. They also will be used to identify critical areas for--and provide technical contributions to--the development of new standards. An information repository containing the MSE models and specifications, as well as other related models, specifications, and software, will be made publicly available on the Internet to serve the needs of system developers, system integrators, and the research and development community.
2 Overview of the scoping activity
An important activity in Phase I of the MSE project has been the further refinement of the following initial broad guidelines:
A primary intention has been to identify a body of work that is appropriate for NIST to undertake, that advances what has been done before, and that will have a high payoff in terms of value to industry. The primary aims in establishing the scope have been to ensure that:
Since product realization processes are not the same for different types of products, it has been necessary to decide on a product domain appropriate for the MSE project. Boundaries also have been defined for the range of product realization activities covered and the aspects of information systems technology taken into account. These decisions and their rationales are detailed in the following sections.
3 Scope of product domain
The manufacturing processes specified in the guidelines quoted above are appropriate for mechanical products. But many familiar artifacts such as kitchen appliances are electro-mechanical in nature, and since a significant sector of U.S. industry manufactures such products, electromechanical products have been included in the MSE project domain. In order to adhere to the guidelines, that domain will exclude the design and production aspects of electrical and electronic components; such components will be treated only as additional parts to be assembled into the final product. This rules out consideration of systems oriented specifically toward electrical or electronic design and manufacture, and avoids possible conflict with other national research programs.
A further reason for excluding electronic products is that design and manufacturing integration in this area is currently more advanced than it is for mechanical products. In the field of microelectronics, for example, it has been possible for some years to proceed in an integrated manner from logic design, through chip layout and functional simulation, to manufacturing planning. This is far from the case in the domain of mechanical products, where geometric problems are more severe and the range of engineering activities is much wider and more diverse.
Even with the above provisos, electromechanical products represent an extensive domain, including the manufacture of parts by
These account for the great majority of mechanical parts made today.
The MSE project will concentrate on these four processes. However, in a time of rapid technological change, it will be important to give some consideration to less commonly used methods that may become dominant in the future. Some of these are similar to the processes listed (e.g., other types of molding and casting, forging, etc.). Less traditional methods include powdered metal forming, filament winding and other composite techniques, electro-discharge machining (EDM), and specialized sheet metal forming processes such as stretch-forming and shot-peening. Solid free-form fabrication processes, including stereolithography and selective laser sintering, currently are used only for prototyping, but may in the foreseeable future be used in production processes. The MSE project will monitor the progress of these emerging technologies; in Phase I however, attention will be restricted to noting their specialized information requirements.
Part materials will include metals, thermoplastics, and composites, the last being increasingly important in the manufacture of aircraft, cars, sporting goods, and medical equipment. Products within the chosen domain may also require materials conditioning operations such as heat treatment, and material finishing operations such as painting or anodizing.
There also is a domain-related aspect to product assembly. Aside from the purely geometrical positioning and orientation of mated parts with respect to each other, this concerns the actual fabrication of large parts from smaller components by joining techniques such as riveting, bonding, or welding. Some of these techniques have been automated, and so are included within the scope of the MSE project.
4 Scope of product realization activities
In order to make the project reasonably self-contained, it will cover the following product realization functions:
Activities covered under each of these headings are listed in the following subsections and described in more technical detail in Part II.
1 Design engineering activities
The design engineering function starts with the requirements for a new product. Its output is a completely documented specification of that product, including a geometric description.
Although the design process can be subdivided in several different ways, for the purposes of this report it is divided into four phases, each with its own output:
Computer aids for the first two phases are largely non-existent today, and they are therefore excluded from the scope of the project. Commercially available rule-based systems are currently used in industry for some aspects of configuration design. Conventional geometry-based CAD systems as well as newer feature-based and constraint-based systems are used for detail design. All these types of design systems fall within the scope of the MSE project.
It must be noted that a high proportion of design activity in industry is not design from scratch, but rather modification or redesign of existing products for improved performance or lower production cost.
A more detailed list of design engineering activities within the MSE project scope includes:
The above is merely a list of functions and is not intended as a system decomposition. These functions are fully described in Part II.
Design is not a one-time-only process; as noted above, redesign for product improvement is common, while design changes also are made in response to feedback from manufacturing engineering, as is shown in the next section.
2 Manufacturing engineering activities
Traditionally, once the design engineering phase is complete, the resulting product specification becomes the input to the manufacturing engineering phase, which essentially determines how the product is to be made. There is a current trend toward concurrent engineering, in which some activities from these two phases are carried out in parallel to shorten the overall product realization cycle. It is important that the results of the MSE project are compatible with this mode of operation.
The following manufacturing engineering activities fall within the MSE project scope:
These activities (which will be discussed in more detail in Part II) fall under the two main headings of planning and simulation. As will be shown below, planning activities may give rise to subsidiary product realization cycles.
Process planning is the task of determining a set of manufacturing operations--and a sequence for those operations--that will result in the satisfactory manufacture of a product. Usually, given a comprehensive set of manufacturing resources, there are many possible manufacturing plans, and a company seeks to find the one that is near-optimal in terms of either cost or manufacturing time.
There are two basic approaches to this problem. Variant process planning methods essentially edit existing plans for similar products, and rely on some form of coding to measure similarity between parts. Generative methods create plans from scratch; they need access to information on available manufacturing resources, but make no prior assumptions about the part itself.
Variant systems are used widely in industry, and most rely heavily on human interaction. Generative systems are increasing in popularity, since they provide greater flexibility and are potentially easier to integrate into larger systems. Since commercial process planning systems of both types are available, both approaches will be included in the MSE project scope. The use of variant planning will require some means for part coding.
There are many examples of feedback from manufacturing engineering into design engineering. For instance, one of the important outputs of process planning is a detailed estimate of production costs; a high estimate may lead to a request for redesign so that the product can be produced more cheaply.
Other planning activities include NC, assembly, and inspection planning. In the case of machined parts, NC planning specifies detailed machining strategies, from which control programs are generated to drive machine tools used in the manufacturing process itself. Inspection planning defines strategies for the inspection of manufactured parts to ensure that they meet their original design specifications. Assembly planning finds sequences by which parts can be assembled into subassemblies and full assemblies. Assembly planning is also relevant to product maintenance and repair, since they usually involve the reverse process of disassembly followed by reassembly.
Most manufacturing processes have specific requirements regarding tooling. For example, machining may require the use of one or more fixtures to hold the part while it is being processed, while injection molding requires the creation of a mold. Thus, once a part has been designed and the manufacturing process specified, an additional product realization cycle may have to be completed to generate the tooling requirements for the main production process.
It is possible to use the output from many types of planning activities to drive graphical simulations of the operations they specify. In an industrial context, this provides a valuable means of checking plan validity without the expense of taking production equipment out of service to carry out real tests on the shop floor.
Simulation also will provide a means for extending the range of activities covered in the MSE project. For example, resource limitations will restrict the number of production methods that can actually be implemented in SIMA demonstration systems. But simulation will allow the MSE project to investigate the integration of other methods. Simulation is therefore essential in the MSE project.
3 Production activities
It is in the production domain that the actual manufacturing processes occur. These are specified during the manufacturing engineering phase, which generates data essential for their control. However, further control data are generated by other activities within the production domain. This is partly because resources usually need to be shared in manufacturing a range of products rather than just a single product.
One boundary to the activities covered by the MSE project was set in the design domain, between functional and configuration design. A reasonably clear-cut boundary also has been identified in the production domain. The activities in the Finance and Administration sector of Figure 2.1 are either not computerized or are not intimately linked to the product realization cycle. The most direct links are those between the production activities and Finance, Procurement, and Distribution. These are relatively narrow information channels, which will be given sufficient consideration during the MSE project to ensure that results may be applied in a wider organizational context in the future.
Production systems handle the following activities:
Production activities determine the products to be manufactured at any one time, the order in which they are produced, and the allocation of resources to their production; they also ensure the quality of manufactured products. These activities are further discussed in Part II, with the exception of the last; although the software systems controlling and simulating them are within the MSE scope, the physical processes themselves (including machining, materials handling, assembly etc.) are not included.
Simulation also plays several important roles in the production domain, primarily in the optimization and verification of production plans. As in the manufacturing engineering domain, simulation will provide a valuable means for extending the effective scope of MSE project through the use of virtual rather than real production facilities.
5 Scope with regard to information systems technology
An integrated product realization system consists of many software modules, each of which may be regarded as an information system in its own right. Examples include CAD systems, planning systems, resource and materials databases, and scheduling systems. Each of these may generate information, store information, acquire information from other systems, or pass information on. Usually, the individual modules will be distributed over a range of hardware platforms. To make these components work together effectively, it is necessary to allow them to share information and to make use of each others' capabilities.
This requires the developers of an integrated system to agree on:
The specification of the functions a system will perform, and the information it needs and provides, is termed a system architecture. The specification of what information exchanges will occur, and how, is termed an interface specification. The MSE project must therefore define system architectures and interface specifications that permit integration of the component systems of design engineering, manufacturing engineering, and production systems. The scope of this activity encompasses:
In the context of protocol and interface specifications the primary focus of the MSE project will be on application protocols (APs) and application programming interfaces (APIs). These are the protocols and interfaces allowing direct communication with the manufacturing application software modules. Additionally, the MSE project will need to identify communications and networking protocols to serve as media for the exchanges.
A major part of the work in this area will stem from the differences between "ideal" and commercially available product realization systems in terms of architectures and interface specifications. One possible approach will be to embed each commercial system in a "wrapper" that makes it appear to comply with the ideal specifications for communicating with other systems. In some cases this will involve converting the native internal information formats of the embedded systems into the chosen ideal formats. Where possible, the MSE project will collaborate with the developers of commercial systems in overcoming these problems.
There are several existing and emerging standards for manufacturing information, systems, functions, and exchanges, and the MSE project will make use of these where appropriate. In addition, detailed architectures and information models proposed by various research consortia may prove valuable. In these areas, the MSE project will identify needs for new standards, make significant contributions to emerging standards activities, and support the broader acceptance and standardization of industry-developed specifications whose use is judged to be beneficial.
There also are numerous existing and emerging general-purpose information technology standards that are potentially relevant to the MSE project. In many cases it will be possible to use corresponding off-the-shelf commercial products, enabling the project to concentrate on the engineering and manufacturing application concerns. Such standards and products will be identified, evaluated, and in some cases used. However, it is not expected that the project will identify the need for new developments in information technology or general-purpose information technology standards.
6 Quality control
Quality considerations pervade the whole of the product realization cycle, and will be considered in more detail in various sections of Part II. The drive for product quality is a unifying influence throughout the domain of the MSE project. The term "quality" is used in both a narrow and broad sense. In its broadest interpretation, it refers to the responsiveness of an institution to societal needs. For a manufacturing enterprise, quality means meeting the needs of customers (end users, in particular) in regard to price, delivery date, and fitness for use. The most common broad view of quality is fitness for use, excluding price and delivery dates from the domain of quality.The definitions used in this section are taken primarily from: Juran, J. M., Quality Control Handbook, McGraw-Hill, 1974. "Fitness for use" is always taken to mean fitness as perceived by the user of a product or service. The evaluation of fitness for use by the producer or supplier is essentially irrelevant to the definition of quality (but not, of course, to the implementation of quality).
For products, fitness for use can be defined in terms of four classes of quality characteristics:
Another characteristic, manufacturability, is often considered a quality characteristic. However, this is concerned with whether a design can be manufactured with a given set of resources. It therefore relates to the quality of design from a company's internal viewpoint, and is not closely related to fitness for use of the resulting product by the customer.
It is clear from the above discussion list that the product specification--the material properties, geometric configuration, tolerances, finish requirements, etc.--is a substitute for the real goal: fitness for use.
It is important to understand the basic terms of quality. The Quality Control HandbookJuran, op. cit., Chapter 2. defines the quality function as "the entire collection of activities through which we achieve fitness for use, no matter where these activities are performed." It also defines quality control as "the regulatory process through which we measure actual quality performance, compare it with standards, and act on the difference." (Note that product inspection is only one part of quality control.) Finally, quality assurance is defined as "the activity of providing, to all concerned, the evidence needed to establish confidence that the quality function is being performed adequately." If quality control is comparable to accounting, quality assurance is analogous to the financial audit.
The MSE project is concerned with the quality function to the extent that quality activities are within the MSE project scope as described earlier in this chapter. Thus, in design engineering, the quality of the specifications resulting from embodiment and detail design are within the MSE project scope, while quality control of the conceptual design is not. The quality of process specifications developed during the manufacturing engineering phase are all within scope. Similarly, quality control of production activities includes the quality of production plans, production control strategies, etc.
All major quality objectives are cross-functional in nature. The MSE project will identify and address a multitude of integration issues regarding the implementation of the quality function. Some of the most obvious opportunities for improving implementation of the quality function involve communication between the activities in the scope of the MSE project. A number of examples can be identified. Design engineering must represent both functional and nonfunctional characteristics, and must identify the difference. (Typically, the Design Department must be a party to any waiver of functional requirements, but need not be for nonfunctional requirements.) Designers must in turn receive enough data to select tolerances, which involves a tradeoff between fitness for use and manufacturing costs. In theory, the designer should perform a formal tradeoff analysis; in practice, this is seldom done, often because of a lack of data or resources to model downstream effects. (This can result in the undesirable situation of unrealistic tolerances being loosely enforced.) Finally, manufacturing engineering must have access to process capability data to design the manufacturing processes for a product.
The MSE project will need to analyze these and other quality considerations in defining a systems approach to manufacturing. All aspects of MSE project work--data requirements, database architectures, functional models, and other elements--are affected by quality control issues.
The major focus of the MSE project is research and development of integration solutions. The implementation of manufacturing systems is not included in that focus, per se. However, because system implementations can serve a number of MSE project goals, they will be an important part of the project. Part of the background study therefore involved an analysis of implementation issues in order to support implementation demonstrations planned for Phase II of the MSE plan. This chapter discusses the study findings in the areas of implementation scenarios, selection of test-case products, selection of system components, and plans for implementing scenarios in Phase II of the MSE project plan.
3.1 Implementation scenarios
Systems implementation can serve three purposes: to demonstrate the feasibility and benefits of MSE project results; to carry out engineering experiments with specific technical goals; and to focus MSE project activities in general. These reasons may conflict in terms of their implementation requirements, and careful attention must be given throughout the MSE project to identify leveraging opportunities.
Demonstrations will be essential for communicating project results to a broad audience of industry, government, and academic visitors, who are likely to visit the MSE project on a yearly basis. They must be designed to emphasize the impact of MSE accomplishments and to point out optimal future directions for the project. The demonstration systems must also be sufficiently polished that their objectives are not obscured by technical minutiae. Test-case products must be chosen to highlight the technologies used to integrate design engineering, manufacturing engineering, and production functions.
The MSE project will carry out engineering experiments to identify and test solutions of specific systems integration problems. Major issues in MSE are interface definitions, testing the feasibility of standards, and systems interoperability. The implementation environment must support these experiments as efficiently as possible. Infrastructure systems--network communications, workstations, operating systems, etc.--should support open, distributed processing to enable these experiments. Test-case products must also exhibit manufacturing problems being addressed by the MSE project.
Developing integration solutions useful to industry requires the MSE project to focus its demonstrations on real-world manufacturing scenarios. The implementation of these scenarios must include software systems and test cases provided by industry collaborators actively working on problems in design engineering, manufacturing engineering, and production. Multiple scenarios will be defined and evaluated in Phase I, in order to devise a scenario that can be supported by the resources planned for Phase II.
3.2 Selection of test-case products
Test-case products will be selected many times throughout the MSE project. This section identifies the criteria to be used in this selection and identifies candidate products. The choice of specific test-case products will be the subject of future MSE project tasks.
Within the product realization process cycle, the nature and level of detail of the information used by different activities varies. Use of a common test-case product throughout the cycle will provide insight into the completeness and correctness of the shared information and its convenience of use in each of the manufacturing activities. The product data will be chosen to encompass all essential information requirements in each domain within design engineering, manufacturing engineering, and production, so that no application is limited by another's unique requirements.
Generally, test-case products should be representative of the mechanical parts manufacturing industry. They should pose challenging manufacturing problems, yet be feasible within the scope and domain of the MSE project. Specific product selection criteria are discussed further below.
3.2.1 Product perception
To serve as demonstrations, test-case products should be familiar to the public, present problems of significance to MSE's customers, and have relevance for a broad spectrum of the U.S. manufacturing industry. Manufacturing problems associated with the products should relate to integration issues rather than to processing technology or other issues unrelated to the scope of the MSE project.
Generally, consumer products are most likely to satisfy these requirements. Workshop tools, kitchen appliances, and certain recreational equipment are likely candidates. High-technology products run the risk that the processing requirements (e.g., extremely tight tolerances) may distract attention from the manufacturing integration issues.
Similarly, defense-related products do not meet these requirements. They are viewed as high-technology, complex, extremely expensive to fabricate, and highly specialized. These products can pose very interesting and highly complex engineering and manufacturing problems, but their choice could also raise controversial side-issues, again shifting attention away from integration problems. In addition, the applications, tools, and integration methods used in the defense industry often differ from those used in commercial industry due to federal guidelines, standards, and contract restrictions. Defense-related industries in any case are the focus of other national research programs.
The following list of product categories consistent with the selection criteria were identified in the study:
3.2.2 Product technical challenges
Ideally, test-case products should pose significant research challenges in all MSE domains. Design engineering research, for example, will benefit from a choice of test-case products having alternative designs so as to allow study of different design scenarios, such as design from scratch versus redesign. Manufacturing engineering research will benefit from test-case products belonging to common product families, allowing study of variant design and variant planning. Production research will benefit from a diverse mix of test-case products, allowing a study of production planning, scheduling, and resource allocation issues.
All MSE projects have recommended that test-case products be assembled from several components. The components of each product should represent various fabrication processes such as machining, near net shape formation (i.e., sintering, castings), and plastic injection molding, in order to test process-specific information requirements. It is also desirable to use a whole product rather than a functional subsystem or assembly within a larger product, so that "uninteresting" components also get considered in the testing. The use of test-case products with multiple components will provide a higher level of project input with respect to integration issues cutting across the major activity areas.
3.2.3 Product manufacturing characteristics
Several manufacturing characteristics affect the feasibility of producing test-case products within the resources of the MSE project. The following characteristics were identified in the background study as well as in recommendations from project participants.
Size/weight: The size and weight of a product is important in that the processes used to manufacture and assemble the product have limitations. Size limitations usually are defined in terms of a "working envelope." This defines the space that a product may occupy at each machine or assembly work station without adversely affecting machine or assembly operations. The weight of a component or assembly also can dictate whether special lifting equipment or specialized machining equipment is required. Based on project input, the work envelope of test-case products should be restricted to approximately 0.1 cubic meter to maximize the number of manufacturers that meet the machining and assembly characteristics.
Complexity: The complexity of a product is a function of the number and diversity of the engineering and production activities required for its realization. The following are the complexity factors considered and the corresponding recommendations:
Manufacturability/Assemblability: Manufacturability and assemblability of components are functions of material selection, manufacturing resources, assembly equipment, tooling, fixturing, and tolerances of manufacturing and assembly features. To achieve cost and quality goals, the product design must take into account manufacturing and assembly processes. Test products should not be extraordinarily difficult to make, because that would tend to divert the research away from integration issues. On the other hand, test products should be such as to make manufacturing engineering considerations important in some of the design choices.
3.2.4 Product availability
Product availability means that the product is either readily available at low cost (e.g., less than $150) or can be easily fabricated. Ready availability would facilitate using an actual product and its components, along with associated CAD models, to demonstrate project results. Using such "concrete" examples would help communicate and clarify key project objectives. On the other hand, the proprietary nature of some products may be a barrier to their use as test cases in the absence of collaboration by the manufacturer.
Two MSE projects have expressed a desire to have some key components of the test-case products fabricated at NIST. The ability to make a test product in-house at NIST depends largely on the processes involved in designing the part. Facilities and equipment to cast, forge, and extrude are not available within NIST.
3.2.5 Market considerations
The volume of production can drastically affect the entire product realization process. A product may be designed quite differently if only one is made, as compared to 100,000. Likewise, manufacturing plans and production requirements may vary significantly with market volume. Test-case products should therefore reflect a range of market requirements to better address these issues.
Special reliability and safety restrictions, such as commonly apply to health-care products, create additional design requirements and also affect the requirements for process control and inspection during production. Such products therefore make good test cases for these aspects of manufacturing systems integration.
3.2.6 Recommendations
Based on consideration of all the factors described above, the background study identified three classes of candidate test-case products, as follows.
Household: A hand-held hair dryer could be a suitable example. This product is familiar to the public. Although it is viewed as low-tech, its design and manufacturing processes meet program guidelines. Due to the product's intended use and the environment in which it is used, strict safety regulations have to be met regarding shock hazard and noise levels. Since hair dryers are produced in high volume, manufacturing process optimization is important to minimize the component and assembly costs. Products from multiple manufacturers are available, which could support the evaluation of alternative approaches to design and manufacturing.
Recreational: A bicycle could be an example in this class. This product is also very familiar to the general public. Bicycles are manufactured by many companies in volumes ranging from very low (exotic racing bicycles) to high (bicycles for the general public). The complexity and number of components and processes match the program guidelines.
Tools: Here a home workshop drill could provide a suitable example. This product addresses all the areas listed for the household product, but is more advanced in terms of its technology content, using tighter tolerances and a more complex assembly.
3.3 Implementation plans
The real-world manufacturing scenarios developed in Phase I of the MSE project will lead to planning and implementation of demonstration systems during Phase II, i.e., in years three through five. This will be undertaken in collaboration with industry in order to ensure that proposed integration solutions support realistic product realization situations. Implementations will make use of the NIST AMSANT facilities in order to perform remote experiments with industry collaborators through the use of advanced networking and communication systems. Integration demonstrations will consist mostly of design to production simulations because of limited access to production resources. The specific topics of industry involvement, the demonstration facility, and simulation systems are discussed further below.
3.3.1 Industry involvement
Industry involvement is an important part of the MSE project. It is for this reason that actual manufactured products will be chosen as test cases, rather than artificial "benchmark products." One benefit from industry participation may be the provision of additional manufacturing support information for the product, such as a bill of material, engineering specifications, process plans, and assembly plans. However, if the chosen product requires industry-supplied knowledge and information, consideration must be given to any conditions that may be imposed on its use and dissemination. The effects on the MSE project of restricted access to proprietary information will need to be carefully evaluated.
Even with limited industry involvement, it would be possible to select a test-case product based on (but not identical to) an actual industry product. This would require significant effort by MSE project staff in creating and validating the product design and its supporting information, however.
Collaboration between industry, other government agencies and NIST is seen as an important, ongoing part of the MSE implementation plan. It is vital that the project remain aware of the broad spectrum of industry efforts to improve the design and fabrication of electromechanical products. It is also important for the MSE project to be aware of other government agency sponsored programs developing supporting technologies, and addressing similar integration problems, in order to eliminate redundant efforts and to leverage technology results supporting systems integration. Specific external programs will be targeted for SIMA participation, and new candidate products and functional subsystems will be reviewed as appropriate. If new product and process technologies are found to be superior to the solutions developed within the MSE project, existing MSE products and technologies will be replaced. MSE implementation scenarios must be realized in conjunction with existing programs whose plans include pilot demonstrations of real-world problems.
It is anticipated that formal relationships (i.e., Cooperative Research and Development Agreements or CRADAs) will be set up with the companies providing test-case products, and with programs developing supporting technologies. Additional collaboration mechanisms such as the NIST Industry Fellows Program will be used to provide NIST staff with the opportunity to work in an industrial setting. These industry collaborations will provide industry validation for the proposed integration solutions developed under the SIMA program.
3.3.2 Demonstration system and facility
The MSE project will include continuous and discrete-event simulations in design, planning, and shop-floor production activities as part of its implementation plans to demonstrate systems integration. Demonstrations of actual parts production will be limited to what can be accomplished using existing resources in the NIST workshops, and/or the facilities of an industrial collaborator. Inevitably, this will limit the real-world scope of the integration demonstrations. Heavy emphasis will therefore be placed throughout the program on the provision of simulation capabilities so that virtual demonstrations are possible over a wide range of part domains and engineering activities.
Virtual demonstrations will be facilitated by the advanced computing and communication capabilities implemented within the AMSANT. The AMSANT will serve as the primary test bed for project demonstrations, technology evaluations, and external collaborations, throughout the five-year duration of the MSE project. AMSANT will provide the MSE project and its collaborators with the ability to perform integration demonstration between multiple sites.