World-class CIM in America.
An example is General Electric's Steam Turbine-Generator Business (STGB), Schenectady, NY--a paperless factory that will help GE respond to an increasingly service-oriented market for electric-generating equipment. A 30 percent reduction in manufacturing cycle time is expected along with significant cost reductions in direct labor, indirect labor, salaried personnel, and inventory. Already the break-even volume has been reduced 70 percent.
"With CIM we are getting the right information to the right people at the right time to make the right decision," says Randall J Alkema, general manager of STGB's engineering and manufacturing department.
Alkema points out that the move to CIM began in 1980 with implementation of a 10-year master plan (updated every two years) calling for computer integration of the entire 10-plant complex--a projected $50-million investment. This is a strategic response to a major shift in the electric-utility industry.
Electric utilities, the primary users of large turbines and generators, are buying few new units. Instead, they are investing in service and parts to run old equipment longer. The change is a result of reduced electrical load growth caused by conservation, high reserve margins, and high financing costs.
Today, STGB's primary business is supplying service and parts for its fleet of more than 4000 operating turbine-generator sets. Whereas manufacturing cycle times in the new-unit business are measured in years, cycle times measured in hours or days are required in the replacement-parts business.
That's particularly true when a generator breaks down. Such occurrences are rare; however, each day the machine is out of service can cost a utility hundreds of thousands of dollars. Now, STGB's small-parts shop (the prototype CIM installation) can manufacture and ship some emergency parts the day the order is received. Similar high-priority orders previously took days.
"CIM also is important in making routine replacement components," emphasizes Alkema, "a business that requires manufacturing parts in high volume in an almost endless variety of designs. For example, in the small-parts shop, a data base contains about 25,000 unique part designs for manufacturing small turbine components such as packing rings, spill strips, packing casings, oil deflectors, bolts, nuts, and studs. The shop (employing 180 people, 24 NC machines, and 90 manual machines) turns out 350,000 parts/year to fill more than 15,000 orders."
CIM begins at order entry, where an automated Honeywell mainframe-based quotation system provides price information to customers throughout North America, Figure 1. When an order is placed, it is logged instantly by an on-line system, which triggers design and manufacturing processes.
An automated process planning system, running on a Data General MV/10000, receives the order from the mainframe and matches it to a part-recognition (group-technology) code. The system determines the most efficient routing for the part, selects the proper materials, and chooses the correct NC family part program.
A Calma CAD system is used extensively in turbine-generator engineering at STGB. Drawings are done on 3-D interactive graphics terminals that have improved productivity about 3:1 over conventional drafting. CAD also enhances product quality by minimizing errors.
The original CAD setup (installed in 1978) consisted of two Data General Eclipse minicomputers and seven graphics workstations. STGB since has expanded its CAD system to include six Eclipse minis and a Digital Equipment VAX 11/780 mini supporting 22 color and black-and-white workstations, two on-line plotters, two off-line plotters, six printers, and 11 alphanumeric terminals, Figure 2.
Software running on the system includes DDM (Design Drafting & Manufacturing) and GDS I (Graphics Display System). The former is used for 3-D mechanical design of steam turbine and generator parts; the latter is used for printed-circuit-board design to support turbine-generator control equipment.
About 1.5 million paper drawings at STGB soon will be stored on optical disks, inscribed and read using lasers, and linked to remote drawing retrieval stations by microwave transmission.
Digital engineering information, significantly enhanced by the DAL (Design Analysis Language) and GPL (Graphics Programming Language) languages, automatically forms the basis for the part-recognition code that electronically defines parts and feeds the process planning system.
The CAD facility operates on three shifts--two for production tasks, one for system operational tasks. More than 100 drafters and engineers have been trained in-house to use the system.
Total factory management
Design information is sent to an NC programming package that runs on a Data General 32-bit minicomputer, which automatically develops required machining data. This information then is downloaded to an NC programming system that processes and postprocesses the family-of-parts program (language is APT IV). Postprocessing generates the estimated time to manufacture the part, which is passed back to the process planning system.
The NC programming system transmits the part program to the manufacturing shop's factory-management system, which provides DNC, shop-floor control, and factory communications.
Shop-floor control consists of programs for material dispatch, scheduling, production control, material tracking, production change capability, labor reporting, machine and process status, and factory instructions. This module uses the same hardware as the DNC and factory-communications systems to operate in an on-line, real-time mode and transmit information to and from the host.
The factory communications function, which provides communications between machine operators and the host computer, is carried out via terminals in the factory, Figure 3. Shop workers receive job assignments through the terminals, for example. Assignments are determined by a computer using a priority algorithm based on customer delivery requirements.
Factory communication provides the network for communications between the operators and their support functions as well, e.g., foreman, methods, production control, quality control, and maintenance. It also passes data back to the business and financial computer systems to keep track of job completions, inventory status, and job costs.
When a machine tool finishes a part, it notifies the factory-management system. The machine operator then enters real-time labor details into the system via the computer terminal. The factory communications module subsequently notifies an inspector that the part is ready.
After examining it, the inspector enters an approval code at the terminal. The factory communications system notifies a materials handler that the part is ready to move to another machine or to shipping. To close the loop, dock workers enter appropriate information into terminals when the part is shipped.
Out on the floor
Computers provide the foundation for streamlining information flow; however, automated machining systems play an important role in CIM as well. One such system at STGB involves a pair of flexible machining cells used for rough milling turbine buckets, a process now completed up to eight times faster than a year ago. The cells are among many NC machining processes being woven into the system.
Buckets, airfoil-shaped turbine parts that convert the energy in high-pressure steam to rotary motion, are manufactured in high volume and in hundreds of designs. Milling contoured stainless steel parts is an exacting operation, as each bucket of a particular design must be identical to others of that design to ensure that the turbine rotor is balanced.
The cells are fed by two robots, Figure 4. Work is carried to and from the system and between cells by conveyors.
The cells can be reprogrammed off-line to handle different bucket designs as the CIM system feeds new customer orders into the shop's load.
Last autumn, the Society of Manufacturing Engineers presented its annual LEAD award (Leadership Excellence in the Application and Development of Computer-Integrated Manufacturing) to STGB's CIM project team. Their effort is a multidisciplinary world-class example of applying advanced manufacturing technologies.
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|Title Annotation:||computer-integrated manufacturing|
|Publication:||Tooling & Production|
|Date:||Jan 1, 1985|
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