CIM begins at home for Texas Instruments.
Texas Instruments' Lubbock, Texas, plant is bringing world-class manufacturing back to the U.S. by using CIM to manufacture a scientific calculator from raw materials to finished product in just 20 minutes. What's most unusual about TI is that the company also manufactures much of the intelligent devices that make up its CIM system for injection molding and assembly.
TI's use of CIM and automation enables its customer, Wal-Mart, to offer the TI-25 Solar calculator to consumers at a price of less than $10. Sales of the TI-25 and other TI calculators have exceeded Wal-Mart's expectations, requiring TI to add a second manufacturing line to meet growing demand. TI expects to ship more than two million "Made-In-The-USA" solar and other calculators to Wal-Mart in 1990 alone.
POSSIBLE ONLY WITH CIM
Paul Greenwood, TI operations manager for the project, conceived the idea of an all-U.S.-manufactured calculator in March 1989. CIM was essential to meet the twin goals of high quality and low price. "Total automation was required to give us complete control over all processes for quality assurance," says Greenwood, who began the project by recruiting an all-volunteer TI army to bring the idea into reality. "Our team accomplished a feat that might qualify as an entry in the Guinness Book of World Records," says Greenwood. "In less than five months, it concurrently developed the product design and manufacturing line, and rolled its first working calculators off the assembly line."
This TI team consisted of experts in design, manufacturing automation, and other disciplines, who worked together to design the calculator for automated manufacturing from the start. The automation program for the TI-25 consists of three phases. The first phase is complete and fully functional. In it, all critical manufacturing stations were fully automated, leaving only a few stations for manual operations. TI plans to implement phases two and three next year, which will fully automate the entire manufacturing system.
The brains and nerve center of the CIM system developed at Lubbock are TI's own programmable controller family and the TI Turbomold (TM) and Cell/View family of injection molding controls. The injection controls were developed fairly recently by TI's Plastics Automation Group in Johnson City, Tenn. (see PT, May '89, p. 77).
"We completed the first phase in August 1990," says Kenneth Barnes, Lubbock equipment engineering manager. "This involved controlling the injection molding presses using TI's PLCs and closed-loop controls, and installing Cell/View Cell Supervisor to link the molding machines," he says. "Turbomold and Cell/View gave us the level of precise control required for the Wal-Mart contract."
Phase One yielded impressive productivity improvements. Lubbock realized a dramatic improvement in part defects, dropping from 5.8/1000 to 0.162/1000. Downtime was reduced by 65%, setup time by 38%, and maintenance by 31%. Cycle times were cut by 23% and scrap by 22.5%. These statistics were obtained by comparing Lubbock's manufacture of similar calculators without the use of Turbomold and Cell View to the manufacture of the TI-25 using Turbomold, Cell/View and the TIWay data-communications network.
The Turbomold family has a high-speed electronic module with dedicated analog I/O circuitry for closed-loop control of both injection and clamping. "We chose Turbomold to control our presses because it provides precise control and could simultaneously handle all manufacturing support equipment, including robots, dryers, chillers, conveyors, and material feeders, and communicate with the plantwide management network," says Barnes.
Cell/View software provides real-time information from the mold floor along with reports and historical trending. On-screen displays, such as "Machine No. x Statistics" and "Injection Cell Overview" permit real-time shop-floor monitoring, SPC and SQC to help maintain high quality and consistency. Customized trend charts are available at operator request, to help the operator make adjustments before problems get out of control. Downloading complete set-up "recipes" from storage also ensures use of consistent processing conditions for quality control.
Information from Cell/View and the TI PLCs pass through the plantwide Ethernet-based TIWay local-area network, and is then stored on several mini-computers. Information is stored and monitored for several essential functions, including the tracking of defect and scrap rates, auditing quality control and monitoring maintenance and spare parts.
TI's Just-In-Time oriented system automatically delivers calculator parts to the assembly as needed. TI vendors communicate by modem directly with the system. This keeps them up to date on warehouse inventories and defect rates, while achieving TI's goal of maintaining low inventory.
Key to achieving low manufacturing cost for the calculators is elimination of costly inspections and storage of work-in-process (WIP). TI accomplished this by tight quality control and elimination of WIP storage.
MOLDING, DECORATING, ASSEMBLY
Dedicated to the calculator line are three 250-ton, Cincinnati Milacron injection presses controlled by TI PLCs. Parts are injection molded with closed-loop controls using the TurboPlastics Injection module. A pick-and-place robot removes parts from the presses and places them into a transfer tooling area called a "boat." The boats transport the parts directly from the presses to the assembly area.
Manufacturing the calculator begins with molding the plastic cases. Resin pellets are vacuum-conveyed from outdoor silos into the molding shop, where they are combined with regrind and colorant before entering the injection presses. The presses make two top and two bottom halves of the calculator case in each machine cycle.
A continuous series of travel boats on a conveyor system transports the molded parts from the molding area directly to the assembly area. When the travel boat arrives in assembly, a pick-and-place robot transfers molded parts to "decorator" boats. Each decorator boat travels on a conveyor through two heat-transfer decorating stations that apply decals to the calculator face. For the TI-25, decorations include the label, TI logo, and scientific labels for keys.
The flexibility of the assembly system allows use of one or both heat-transfer stations, depending on the calculator model. This flexibility allows the same manufacturing line to produce the TI-25 and other models of calculators with few adjustments.
The final decorator station applies the date code to the back of all calculators. A pick-and-place robot transfers top and bottom plastic halves from the decorator system to the assembly line. The assembly system transports the calculator parts through assembly and testing stations to the packing and shipping area.
As in the molding area, all critical assembly steps are fully automated. Although several assembly stations currently have workers manually inserting electronic components into the calculator housings, these will be replaced with fully automated stations in later phases.
Once all components are inserted, the next stations use an automated process to heat-seal components into the top and bottom halves of the calculator. Finally, a robot joins the top and bottom parts of the calculator by ultrasonic welding. A transfer gate then moves the fully assembled calculator to the final test line.
Here, workers perform manual drop tests and a series of calculation tests to ensure electrical functionality. A worker enters detected problems and other information into the data collection system, which communicates with the TIWay network. Reasons for product rejection and quality data are displayed in real time on a large marquee that's easily read by workers in the assembly area. From the display, workers read the latest reports on production and quality. This feedback allows workers to make immediate adjustments and monitor their progress.
A conveyor places products passing the quality-assurance tests into a container, where a worker carries them to the packing and shipping area. There, a worker places the calculators in blister packs, a machine heat-seals the packages, and a worker packs them in boxes.
DESIGN FOR ASSEMBLY
TI Lubbock offers several innovations in calculator design and manufacture, according to Peter Chia, an automation engineering manager who played a large role in designing the TI-25 manufacturing line. "These innovations enabled us to meet Wal-Mart's requirements for high quality and low cost," he says. The first step toward lowering costs was reducing the total number of parts in the TI-25 to seven. "This is the lowest number of parts in the world for a scientific calculator," says Chia. "This allows Wal-Mart to price the TI-25 20% lower than any scientific calculators manufactured anywhere in the world including Thailand, China, Malaysia and the Phillipines."
The next step was to design the calculator and the machines to use heat sealing and ultrasonic welding. The automated sealing and welding processes eliminate use of screws and simplify assembly. "This is the first time ultrasonic welding has been used in calculator manufacturing," says Chia.
NEXT STEPS IN AUTOMATION
TI plans to beat its own 20-min manufacturing time achieved at the end of Phase One of the project by replacing manual assembly with automated methods in two additional phases. In Phase Two the conveyor system will be extended to automatically transport calculators passing quality-assurance tests to the shipping and packing area. There, a pick-and-place robot will place each calculator onto its cardboard blister-pack backing, which will then be automatically sealed to the blister.
In Phase Three, TI will have machines instead of workers insert the electronic components into the calculator housings. As the machines are integrated into the system, workers will be reassigned to other manufacturing lines. Additional plans include using surface-mount equipment to assemble the circuit boards and all other components at Lubbock. An outside vendor currently supplies preassembled circuit boards.
PHOTO : Texas Instruments' CIM operation enables it to mold, assemble and package this calculator in 20 minutes, while enabling its customer, Wal-Mart, to offer it to consumers for less than $10.
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|Title Annotation:||1990 CIM Leaders; computer-integrated manufacturing|
|Author:||Fallon, Michael R.|
|Date:||Nov 1, 1990|
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