With competitive pressures in most industries at a fever pitch, CIM is truly an idea whose time has come.
Integrating machine-toolcontrollers with local-area networks so they can chat with engineeringminicomputers that talk to general-business mainframes can reinvigoratean existing plant. And it is. An example is General Electric’s Steam Turbine-GeneratorBusiness (STGB), Schenectady, NY–a paperless factory that will help GErespond to an increasingly service-oriented market forelectric-generating equipment. A 30 percent reduction in manufacturingcycle time is expected along with significant cost reductions in directlabor, indirect labor, salaried personnel, and inventory. Already thebreak-even volume has been reduced 70 percent. “With CIM we are getting the right information to the rightpeople at the right time to make the right decision,” says RandallJ Alkema, general manager of STGB’s engineering and manufacturingdepartment. Why CIM? Alkema points out that the move to CIM began in 1980 withimplementation of a 10-year master plan (updated every two years)calling for computer integration of the entire 10-plant complex–aprojected $50-million investment.
This is a strategic response to amajor shift in the electric-utility industry. Electric utilities, the primary users of large turbines andgenerators, are buying few new units. Instead, they are investing inservice and parts to run old equipment longer.
The change is a resultof reduced electrical load growth caused by conservation, high reservemargins, and high financing costs. Today, STGB’s primary business is supplying service and partsfor its fleet of more than 4000 operating turbine-generator sets.Whereas manufacturing cycle times in the new-unit business are measuredin years, cycle times measured in hours or days are required in thereplacement-parts business. That’s particularly true when a generator breaks down. Suchoccurrences are rare; however, each day the machine is out of servicecan cost a utility hundreds of thousands of dollars. Now, STGB’ssmall-parts shop (the prototype CIM installation) can manufacture andship some emergency parts the day the order is received. Similarhigh-priority orders previously took days. “CIM also is important in making routine replacementcomponents,” emphasizes Alkema, “a business that requiresmanufacturing parts in high volume in an almost endless variety ofdesigns.
For example, in the small-parts shop, a data base containsabout 25,000 unique part designs for manufacturing small turbinecomponents such as packing rings, spill strips, packing casings, oildeflectors, bolts, nuts, and studs. The shop (employing 180 people, 24NC machines, and 90 manual machines) turns out 350,000 parts/year tofill more than 15,000 orders.” CIM begins at order entry, where an automated Honeywellmainframe-based quotation system provides price information to customersthroughout North America, Figure 1.
When an order is placed, it islogged instantly by an on-line system, which triggers design andmanufacturing processes. An automated process planning system, running on a Data GeneralMV/10000, receives the order from the mainframe and matches it to apart-recognition (group-technology) code. The system determines themost efficient routing for the part, selects the proper materials, andchooses the correct NC family part program. Doing drawings A Calma CAD system is used extensively in turbine-generatorengineering at STGB. Drawings are done on 3-D interactive graphicsterminals that have improved productivity about 3:1 over conventionaldrafting.
CAD also enhances product quality by minimizing errors. The original CAD setup (installed in 1978) consisted of two DataGeneral Eclipse minicomputers and seven graphics workstations. STGBsince has expanded its CAD system to include six Eclipse minis and aDigital Equipment VAX 11/780 mini supporting 22 color andblack-and-white workstations, two on-line plotters, two off-lineplotters, 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 usedfor 3-D mechanical design of steam turbine and generator parts; thelatter is used for printed-circuit-board design to supportturbine-generator control equipment. About 1.
5 million paper drawings at STGB soon will be stored onoptical disks, inscribed and read using lasers, and linked to remotedrawing 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 codethat electronically defines parts and feeds the process planning system. The CAD facility operates on three shifts–two for productiontasks, one for system operational tasks. More than 100 drafters andengineers have been trained in-house to use the system. Total factory management Design information is sent to an NC programming package that runson a Data General 32-bit minicomputer, which automatically developsrequired machining data. This information then is downloaded to an NCprogramming system that processes and postprocesses the family-of-partsprogram (language is APT IV). Postprocessing generates the estimatedtime to manufacture the part, which is passed back to the processplanning system. The NC programming system transmits the part program to themanufacturing 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 changecapability, labor reporting, machine and process status, and factoryinstructions. This module uses the same hardware as the DNC andfactory-communications systems to operate in an on-line, real-time modeand transmit information to and from the host. The factory communications function, which provides communicationsbetween machine operators and the host computer, is carried out viaterminals in the factory, Figure 3. Shop workers receive jobassignments through the terminals, for example.
Assignments aredetermined by a computer using a priority algorithm based on customerdelivery requirements. Factory communication provides the network for communicationsbetween 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 systemsto keep track of job completions, inventory status, and job costs. When a machine tool finishes a part, it notifies thefactory-management system. The machine operator then enters real-timelabor details into the system via the computer terminal. The factorycommunications module subsequently notifies an inspector that the partis ready.
After examining it, the inspector enters an approval code at theterminal. The factory communications system notifies a materialshandler that the part is ready to move to another machine or toshipping. To close the loop, dock workers enter appropriate informationinto 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 aswell. One such system at STGB involves a pair of flexible machiningcells used for rough milling turbine buckets, a process now completed upto eight times faster than a year ago. The cells are among many NCmachining processes being woven into the system. Buckets, airfoil-shaped turbine parts that convert the energy inhigh-pressure steam to rotary motion, are manufactured in high volumeand in hundreds of designs.
Milling contoured stainless steel parts isan exacting operation, as each bucket of a particular design must beidentical to others of that design to ensure that the turbine rotor isbalanced. The cells are fed by two robots, Figure 4. Work is carried to andfrom the system and between cells by conveyors. The cells can be reprogrammed off-line to handle different bucketdesigns as the CIM system feeds new customer orders into the shop’sload. Last autumn, the Society of Manufacturing Engineers presented itsannual LEAD award (Leadership Excellence in the Application andDevelopment of Computer-Integrated Manufacturing) to STGB’s CIMproject team. Their effort is a multidisciplinary world-class exampleof applying advanced manufacturing technologies.