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Enabling Technologies for Unified Life-cycle Engineering of Structural Components 3 MANUFACTURING CURRENT ENVIRONMENT Manufacturing currently is informally linked to the initial design process described in Chapter 2. It traditionally starts with only planning and support personnel working with the design community. The transition to the factory floor consists of a series of steps from concept through demonstration, validation, full-scale development, and finally production, with a more formal organizational link to design as production nears. However, as with the design effort, each phase involves shifts in personnel and learning curves for new personnel on the project. Manufacturing-Design Interface Where ULCE concepts are included in the current manufacturing environment, they begin with the interface of the design engineer and the manufacturing engineer during the preliminary design phase of the project at hand. As noted in Chapter 2, however, the computer tools that support the conceptual phases of the design do not have the interface capability or the accuracy necessary for direct use by manufacturing. Computerized cost-estimating tools, design assessment and models of the manufacturing process are not generally available in easy-to-use packages that are integrated with data from other functions in the company. As the product progresses through its various development phases and enters the initial production design phase, manufacturing value process engineers periodically review the engineering drawings to identify producibility issues and make cost evaluations. Although design engineering considers the design frozen from the manufacturing point of view it is still flexible, since design engineering generally continues to make minor design changes well into production. The series of "minor" revisions can significantly affect manufacturing; long lead-time items on order may have to be changed and process revisions made that could affect costs. Again, as with the preliminary design phase, the computer tools that support the detailed design phases of the parts technical planning do not have the interface capability or the accuracy necessary for direct use by manufacturing. Cost trade-off studies are initiated by the design team leader to compare costs of alternative fabrication or machining methods based on past experience and process upgrades being developed for production. Producibility issues are handled informally, and significant problems are frequently not highlighted until very late in the
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components development cycle. Proper development of a defect-free production environment frequently suffers because producibility problems are left to be solved in production. Computer-Integrated Manufacturing Automation is generally not now widely applied to inspection and assembly activities in the aircraft industry. Quality assurance activities are focused primarily on inspection after components have been processed. Inadequate effort is directed toward relating statistical manufacturing process capabilities to design requirements, and statistical process capability data are usually not made available to the designer in either a timely manner or in a usable forum. Joints and attachments are difficult to control directly and to test for process defects. Statistical process control is sometimes used to help the manufacturing engineer control the manufacturing process, but more often it is used by the direct labor force for visual display of process performance rather than trend analysis and control. Progress on computer-integrated manufacturing (CIM) in industry has delivered mixed results—successes, failures, and often unmeasurable effects. It is generally agreed that there is still too much reliance on paper as the communication method in both the design and manufacturing functions. The task of transferring product definition from design to manufacturing with sufficient accuracy to meet the necessary tolerancing and dimensioning requirements of the parts is very difficult. CAE software systems for manufacturing engineering for activities like tool design are emerging but currently are too difficult to adapt and apply, especially by interfacing existing data from the design systems. CAM systems related to machine-tool control to make the components via numerically controlled machines still function for the most part in an off-line fashion. This approach requires skilled parts programmers with extensive shop experience—a very difficult combination of skills to acquire or train people for today. Techniques are emerging to model manufacturing processes to improve yield, material flow, and product quality. Manufacturing engineers are, however, just beginning to use computer capabilities to assist in process planning, tool management, proactive quality control, and automatic data acquisition and testing. Sourcing Most products are manufactured by the same company that designed them. However, weapons systems generally involve many subcontractors and a multi-tiered vendor base. This requires extensive, accurate, and timely communications based on compatible computer information systems for both internal and external communications; such systems are just starting to emerge. Electronic data interchange (EDI) standards are beginning to be effective, at least in administrative areas like traffic and accounts payable and receivable. The manufacturing environment today uses computer assistance for very focused detail efforts or large-volume data processing. Integration with the design function, major weapon systems integrator, and subcontractors is minimal, requiring backup procedures for historical data and audit trails. There is a real "islands of automation" situation in information processing for manufacturing today. FUTURE ENVIRONMENT In the future, manufacturing will be an integral part of a product resource planning and control system, linking design, manufacturing, quality, vendors, assembly, and field service operations. This system will be the foundation for the implementation of real-time, two-way
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components information flow. Computer-based technology will provide the foundation for the efficient small-lot manufacturing so essential to the aerospace industry. Design-Manufacturing-Support Interface Early and continually in the design cycle, engineering will be able to analyze the impact of proposed new materials and processes that are critical in state-of-the-art products. The basis of this analysis will be a mathematically accurate, solid-model-based, feature-driven definition of the required parts. The technically complete definition will be easy for the designer to use and to communicate with production and outside suppliers. This concept will be the basis for a true "art-to-part" system, with greatly reduced total cycle time to market a product incorporating design for performance, quality produced to the required cost and schedule, and effective support in the field. Factories will need fast and accurate transfer of all necessary data from the engineering function to make the part. Linking the design and manufacturing functions will be a unified manufacturing and engineering product definition data base and a corresponding design release and control system. This integrated structure will be the major change in the manufacturing environment and will foster the responsive and automatic flow of design data to manufacturing. This will enable production in a computer-driven, truly flexible network of focused process production facilities consisting of both internal and vendor shops. Fully computerized audit trails will be incorporated, and decisions on items from material selection to weight constraints will be stored for later retrieval and review. The geometric definition will flow into the fully integrated and computer-based manufacturing process planning system, which will ensure that the correct process and techniques are planned for the part. All required production documentation, from routing sheets through time standards and related job sheets, for all operations, including inspection, will logically flow from the engineering data. Also included in the overall information flow will be the numerical data necessary to run the automated factory equipment (machining, assembly, and inspection). All of these numerically controlled software routines will be automatically generated directly from the product definition data file. This will include the critical software verification tasks like tool path analysis to ensure producibility clearances and tolerances to design intent. In addition, all numerically controlled machines will be under adaptive control to ensure that the parts are made exactly to specification. Support tools and master models for production tooling, especially in the new materials areas like composites, will also be generated directly from the product definition. The establishment of a unified and integrated design and production data base will enable manufacturing to have the as-built quality data available for life monitoring and life-cycle analysis by field support. This will be the final link in closing the loop of product monitoring and control via life-cycle engineering principles all the way through the life of the product. Computer-Integrated Manufacturing The key computer technology applications within manufacturing will be flexible and effective real-time status, automatic data capture, and real-time process control. Each focused plant will have increased process integration using automated material-handling systems. Tied into the process flow will be automated nondestructive evaluation (NDE). In contrast to today's experience new NDE techniques will quickly catch both product discrepancies and, more
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components importantly, will identify any adverse process performance trends before product specification limits are reached. NDE will be an integral part of the manufacturing process rather than being used solely in post-process audits, as is generally the current practice. The result will be continuous process capability analysis, which in turn can guide process performance improvements. Manufacturing will finally be given the tools necessary to run the plant in a controlled, continuous flow. Finite scheduling will be possible that will control all critical shop resources: material, tool, fixture, part programming, human resource by skill, etc. The real advantage will be the highlighting of all waste—which in the total quality view includes any nonproductive step, effect, or delay—in a timely fashion so that the process can be remedied immediately. In the area of critical and complex processes, the advanced sensor data capture and analysis capabilities will allow fast, precise process capability and performance analysis studies. This will cause a fundamental switch in the maintenance of manufacturing resources from preventive maintenance to predictive maintenance. Factories will be able to produce efficiently small lot sizes approaching a batch size of one via computer-based scheduling and dispatching systems that will be flexible and responsive. They will meet the real need of the manufacturing enterprise on the shop floor. The emerging concept of integrating simulation, emulation, and expert systems will allow truly flexible scheduling systems that will match the flexible manufacturing environment. Sourcing Product component sourcing will be based on process technologies and on group technology coding. The individual components required for a product (or subproduct) will be produced in specially designed factories and will feed the final assembly steps at a pace equal to the product flow rate. This method of logistics planning and control is sometimes called continuous flow manufacturing (CFM) or just-in-time (JIT) replenishment. Advanced computer-based simulation will highlight both physical barriers and bottlenecks at various states of automation, based on either a real or proposed production plan. The availability of costing data from the cell operating in various stages of automation will be a valuable byproduct of future simulations. Sourcing decisions will favor retaining leading-edge process technologies for competitive advantage in flexible, efficient automated factories. Where the design exceeds the constraints and capabilities of the automated cell, a quick and early producibility alert will be signaled. This will allow for a timely analysis of the option to change the design, increase the flexibility, or change the capability of the cell prior to release for production. SIGNIFICANCE OF THE CHANGE In the future, most factory and office workstations will be directly connected to an integrated computer environment. All nodes in the automated system will either supply control or guidance to the process directly and/or receive information and status. This integration will foster a major change in the outlook of manufacturing engineers and require modification of training of future manufacturing engineers. There will be two new main thrusts. The first will be to expand the concepts of process analysis and process dynamics, emphasizing total systems rather than components and production engineers will need to participate with their counterparts in design in the initial process of product concept, embodiment, and choice of material, leading to the
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Enabling Technologies for Unified Life-cycle Engineering of Structural Components consideration of method of manufacture. Tasks will extend to cover maintainability by field support, with all the implications for logistics, service, and repair. The second thrust will be to emphasize team aspects of project management and economic considerations that greatly influence successful manufacturing projects.
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