Like any good doctor, each machine operator at Amcor’s PET (Polyethylene Terephthalate) Packing plant in Blythewood, S.C., carries a pager. Because the operators there tend more than one machine, they rely on one-way alphanumeric pagers to keep in touch with their automated charges as they go about their business of producing plastic bottles and preforms for the food and beverage industry.
When one of the injection-molding, labeling or blow-molding machines begins to exhibit symptoms of a developing problem, the ailing machine calls its operator, transmitting a short message identifying itself and explaining the trouble it’s having. Using this information, the operator then decides on the best course of action, that is, whether to complete the task at hand or to go to the machine to examine it and administer the appropriate corrective action.
This kind of communication between operators and their machines is becoming increasingly commonplace in automated factories that practice lean and just-in-time manufacturing—thanks largely to computer and information technologies that were developed initially for consumers and offices. In some cases, these technologies have been available to consumers commercially for years at OfficeMax and other retail stores.
The migration of these so-called commercial off-the-shelf technologies (COTS) onto the factory floor shows no signs of slowing. And, “they haven’t even had their most significant impact yet,” says Keith Campbell, executive director, OMAC (Open Modular Architecture Control) Packaging Working Group, at the Louisiana Center for Manufacturing Sciences. He points to the acceptance of a number of commercial devices on the factory floor: personal digital assistants (PDAs), tablet personal computers (PCs), cell phones and wireless communications.
“If anything, we’re seeing a narrowing of the time gap between the creation of these home and office technologies and their adoption in the manufacturing environment,” notes Ron Sielinski, senior industry technology strategist, at Microsoft Corp., the Redmond, Wash., software company. A case in point is the PDA. A pocket PC, it was originally designed for people on the go, but has already found a home in progressive factories.
“Most people in the home and office environments are using PDAs to keep track of their calendars, their contacts, and, to a certain extent, their inboxes,” continues Sielinski. “In the manufacturing environment, however, people are using the devices differently.” Here, PDAs contain custom applications that help users to perform tasks, such as preventive maintenance or troubleshooting problems, while walking around the machine. Using a PDA equipped with wireless communications, a technician even can search manuals and engineering drawings without having to drag them to the machine and flip through hundreds of pages.
The use of tablet PCs in the factory has grown in a similar way. Originally designed for people on the go in the office, tablet PCs have the same basic capabilities as PDAs, but the screen real estate is larger. A common application is shipping and receiving. “It’s very easy to go down a manifest [on a tablet PC] and check things off,” says Sielinski. Users can insert a digital signature and submit the manifest to either the supply chain execution system or an order management system.
Mining for Information
Although wireless communication is the most visible of these so-called commercial computer and information technologies, many more are at work behind the scenes at Amcor. Each machine at the Blythewood plant is connected to a sophisticated PC and Ethernet-based computer network that contains elements that are industrial versions of technology originally developed for home and office computing. Besides the Ethernet infrastructure and the PCs themselves, one of these elements is the real-time historian in the software from Lake Forest, Calif.-based Invensys Wonderware that processes the raw data coming from the machines, gleans useful information from it and distributes the information to the places that need it.
The PCs controlling each machine or group of machines send process information directly to Wonderware’s IndustrialSQL Server, a real-time database organized around Microsoft’s structured query language (SQL). Wonderware essentially built it upon Microsoft’s SQL Server, adding some functions that allow it to store large amounts of data much more quickly than is required for general office use. “We have systems that process 40,000 to 50,000 transactions per second, which is three to four times what the New York Stock Exchange does,” notes Tim Sowell, vice president, ArchestrA Product Strategy, Wonderware.
For retrieval of data, the company developed a number of reporting tools that leverage other technologies. Tools for the Microsoft Office suite, for example, simplify report generation. According to Sowell, these tools solve one of the biggest problems the software industry has today—that is, teaching the users in a plant to use new software. Appearing as buttons at the top of Excel and Word tool bars, the tools help users to generate a Word template that queries the database and populates itself with the appropriate information automatically. “Now all you do is open up that Word document, and you can e-mail it anybody or print it,” says Sowell.
At Amcor’s Blythewood plant, the network’s server collects process data automatically as injection molding machines produce test-tube-shaped preforms, its blow-molding machines transform them into soft-drink bottles and other plastic containers, and its labeling machines apply the appropriate graphics. Besides giving operators and management the ability to study historical data, the network also allows them to view live data from multiple sources simultaneously.
This ability gives technicians and engineers greater control over the molding operations. In injection molding, for example, melt and coolant temperatures, injection and packing pressures, and the speeds of various components in the machine are all process parameters inside the equipment. Ambient temperature and humidity, however, also are process parameters, but are parameters external to the equipment. “There is no way really to get your arms around the process without putting all of them into one report or one graph where you can see the interactions,” says Thom Iwancio, controls engineering manager at Amcor. And the industrial version of SQL Server provides the means to do so.
Although management can view all of the crucial internal and external parameters in real time, it needn’t. Scripts running in the background automate the task, watching for changes in each variable. When a variable exceeds either its upper or lower control limit, the software activates an alarm and pages the operator. The goal is to keep the process in control. “If you can keep your process in control, then you know that you are making good parts,” says Iwancio. “Quality control really just becomes final inspection.”
Machines Talk Too
Giving people access to computer networks and control over machinery is not the only use for commercial information technology. This technology also is instrumental for connecting industrial machinery to computer networks, coordinating their activity with other machines and monitoring their work. A good example is a robotic assembly line putting together automotive dashboards at a Delphi Delco plant in Troy, Mich. On this assembly line, robotic screwdrivers must apply the specified torque to the fasteners, and records of the applied torque must be stored for both self-imposed quality control and regulatory-compliance reporting.
As components come down the line, a barcode scanner reads each part’s serial number and transmits it to a SNAP Ultimate I/O (input/output) system, an Ethernet-based remote control, monitoring, and enterprise data acquisition system from Opto 22, a Temecula, Calif., technology firm. Using this information, the robotic arm can query a Delphi Delco database for the appropriate torque for the component at hand and then report torque measurements back to the database for quality control calculations and validation records.
Wireless communications seems to be gaining a measure of popularity in automated factories. “The same technologies that are used in wireless phones for person-to-person communications are being tweaked a little and deployed in industrial environments,” says David Crump, a spokesman for Opto 22. “So instead of connecting people, you’re connecting a person to a machine or a machine to a machine.”
He believes that the wireless technology is the way of the future. Not having to string wire not only cuts costs but also offers users the flexibility to move equipment wherever they like without worrying about access to a port. Consequently, Opto 22 is working with Nokia, the Espoo, Finland-based telephone manufacturer, to make communications between machines as simple and cost effective as it is currently between two people.
They and their competitors have made great strides in making this goal a reality. “Standards such as GSM/GPRS (Global System for Mobile Communication/General Packet Radio Service) in the cellular world, and IEEE 802.11 in the wireless LAN (local area network) arena are making wireless cheap and inexpensive to install,” reports Crump. “In fact, installation can be much cheaper than running the cable that you need for a wired application.” This is especially true when assets such as storage tanks are in remote locations.
Wireless technology also is finding application in environments that are too harsh for wired networks. For example, splashing water from a nearby waterjet-cutting operation is the reason that a Grupo Antolin plant in Hopkinsville, Ky., relies on an IEEE 802.11-based wireless I/O system from Opto 22 to control robots assembling headliners for automobile interiors. Aside from the wireless connection to the computer network, the application is similar to the one at Delphi Delco: A barcode scanner on the assembly line reads the serial number and transmits the information to the control station, which then tells the robot what the appropriate assembly routine is. By not having to separate the waterjet cutter and the assembly robot, the factory not only increased throughput, but also made its quota with fewer people in 2½ shifts, rather than three.
Web Makes Links Easy
互联网协议(ip) and browsers are additional commercial technologies that hold great potential in manufacturing—potential that factories are striving to tap as a means of simplifying the flow of information between platforms. “The full set of Internet protocols is a low-cost, ubiquitous way of sharing information,” says Sielinski, at Microsoft. “So many business applications expose their user interface through the browser.”
An advantage of software interfaces built with Internet protocols is that computer networks can exploit the power of the Java applets and other plug-in technologies that produce the graphic displays on Web pages. Java applets make checking the status of a machine as easy as checking stock quotes, sport scores, or the weather on the Web. “You just go to the Web page, and click it,” says Mike Broussard, manager, Ethernet-enabled automation and control products, at Schneider Electric’s New Orleans office.
此外,数据的位置变得irrelevant. “It could be in the plant manager’s office, on the factory floor or anywhere in the world,” say Broussard. “You don’t have to go around with a clipboard checking levels or alarm lights. You can sit in your office and pull up the Web page.” Even better, the script can page or e-mail a maintenance person or an engineer when things go awry.
Another advantage of Internet technology is that the software exists in one location. “So you don’t have to buy a $5,000 license for every machine that you want on the network,” says Broussard. Not only is buying individual licenses for each machine expensive, but “it’s kind of a bear to maintain, because you have to actually update each machine” as upgrades become available.
Internet protocols also are helping to streamline the flow of data between databases. Despite the robustness of relational databases built on Microsoft’s SQL Server technology, many industrial automation systems experience lag in data exchanges, mostly because the data flow from the machine through a human-machine interface (HMI) before arriving at the database. Consequently, many hardware companies are developing methods for bypassing the HMI and allowing the data to flow directly into SQL Server. One method of doing so is to combine a Web server—such as Microsoft’s Internet Information Server (IIS)—to the SQL Server database. The technique allows the database to exchange extensible markup language (XML) data directly with equipment on the plant floor.
XML is a unicode scheme (of mostly ASCII characters) being championed by Microsoft for tagging data so that any platform can search the database for the tag and find what it needs. “We’re envisioning XML Web Services as a technology that will be appropriate for virtually every communication scenario,” says Sielinski. “Microsoft and our partners have been defining a very low cost way for solving fairly hairy technical problems with respect to the exchange of information, particularly interoperability and the transparency of these messages going through things like firewalls.” The OPC (for OLE for Process Control) Foundation has already published its first tagging standard for XML Web Services.
These strides toward helping various platforms to share data with one another will have enormous consequences for supply chain management, as well as for the technician or engineer who is on call. Imagine receiving a page or phone call from the machinery while you are half way home on a 50-mile commute. With this technology, you will be able log into the Internet with the nearest computer, look at the problem, and decide either to make the appropriate adjustments online or to return to the plant. The machines stay healthy, and the people get some rest and relaxation—which is good medicine for both man and machine.
