PCs Cover Coating System Control
Semicore Equipment Inc, based in Livermore, CA, manufactures vacuum coating and etching systems for the electronics, optical, solar energy, medical, automotive, military, and related high technology industries. Semicore vacuum sputtering and thin-film evaporation systems provide coatings for a variety of materials including plastics, glass, ceramics, metals, and hybrid substrates. Serving such a wide range of industries with a vast array of machine types requires flexible and highly scalable controls.
The company works with customers from the design concept stage through the machine assembly and installation stages. The company also remanufactures outdated machines to bring them up to speed with the latest in hardware and automation technology. Even though it uses high-end technology, Matthew Hughes, president, and Trey Haight, operations manager, always keep a “maintenance point-of-view” when designing systems. “We ensure that our machines perform well beyond the competition, but still have operational and trouble-shooting capabilities that are simple for users to work with,” Hughes says.
Semicore machines use special vacuum technology to apply gaseous or particle materials to surfaces on the outside and inside of various part shapes. These materials must be applied in chambers that have the pressure reduced to assure freedom from atmospheric contamination. When the chamber environment has been purified, coating materials are applied through sputtering or evaporation processes. Coating materials may include high purity gold, platinum, silicon, titanium, and tungsten.
Unburdening the CPU’s back
Having abandoned PLCs in favor of PC-based control more than seven years ago, the company’s engineers are well beyond debating whether to use PC-based control: they live by it. Older PC-based Semicore systems, however, used software coded in Flow Chart for control and in Visual Basic (VB) for human machine interfaces (HMIs), and it became apparent that the software platform had become a legacy product with little true advancement for it seen on the horizon. The software was also a substantial drain on CPU performance, causing maxed-out PC processors without the ability to run other applications quickly or smoothly.
The company’s PC provider also lacked an acceptably scalable hardware line. Semicore needed products ranging from very low end, inexpensive controllers (to suit specific application demands and migration options) to the highest performance processors available. Another difficult challenge was the possibility of failures in RS232 communication to gauges, power supplies, gas controls, and motion.
Lightening the CPU load
Acknowledging that big changes were needed to determine the automation future at Semicore, Hughes and Haight gathered a great deal of information on major PC-based controls providers. They found what they considered the ideal match at the Semicon West 2005 trade show in San Francisco. “Trey and I both spent a lot of time in the Beckhoff Automation booth at the show,” Hughes said. “We quickly learned that Beckhoff had the scalable control solution for us.”
The result of Semicore’s ambitious controls automation initiative was the company’s advanced HMI and control package. This system incorporates Beckhoff’s C6330 cabinet-mount industrial PCs, CP7802 control panels, TwinCAT automation software, distributed I/O networked over Ethernet TCP/IP via BK9000 bus couplers, Ethernet switches, AM3044 motors, and AX2006 servo drives.
The first application of this new control system was implemented on one of the most complex machines the company had ever built. “It was really a trial by fire because the first application was as demanding as it gets in our industry,” Hughes said. “The project was to develop a brand new coating system that applied diamond-like carbon, chromium carbide, and titanium nitride coating on internal surfaces.”
This coating method is used to increase the life of pipes used in gas, chemical, and petroleum applications. “It’s not difficult to apply wear and corrosion resistive coatings to the outside surfaces of pipes,” Hughes said. “Coating the inside of pipes is where it gets tricky.” The plasma and vacuum-based machine had high frequency control, arbitrary waveform generation with multi-channel scope feedback, and highly complex gas-management functionality.
The coordinated motion axes on Semicore machines are highly dynamic and require very accurate positioning systems. Beckhoff’s TwinCAT software handles the transport and positioning system motions throughout the coating process. The software also proved helpful to Semicore in developing its HMI. “TwinCAT works well with VB. As a result, we can very easily create our own event-based HMI software,” Haight says.
“Also, we went from well over 90% CPU usage on our old polling-based system to less than 10% usage with the new event-based system. This means that we’re free to use a variety of other software applications without hitting CPU performance limits,” Haight said. “The software has also given us the ability to switch a machine from zero manual control to full manual control in hours. With our previous systems, this process could take weeks.”
In addition, the flexibility to code within a multi-language IEC 61131-3 programming environment saved the company hours of programming time. “I enjoy the option to code in Structured Text rather than Flow Chart, since it fits my programming background,” says Haight. “The software allows programmers to choose code languages to fit their skill sets and specific application requirements.”
Semicore achieved further streamlining because of the Beckhoff I/O system’s flexibility. With more than 200 terminal types, Semicore had access to a full range of analog and digital I/O as well as numerous special function cards that helped eliminate third-party devices and greatly reduced the required cabinet space. In order to improve troubleshooting efforts for customers, Semicore used digital and analog interfaces via bus terminal I/O wherever possible.
“Explaining serial RS232 to a non-electrical engineer is sometimes very difficult,” Haight said. “But with bus terminal I/O, we can very easily teach customers to use a voltage meter on analog or digital I/O to quickly determine if a device is operating properly or not. This takes a great burden off the Semicore support team and avoids confusion for customers.”
In addition, KL2612 relay output terminals eliminated the need to purchase additional power supplies or develop special circuitry in-house. These terminals have two relays, each of which has a single contact. The relay contact is connected to the power contacts, which are suitable for use at up to 230 V ac and can easily be used for switching devices requiring main power.
“There are several other examples where the flexible bus terminal I/O helped us fill small gaps for which we would have had to develop our own solutions in the past,” Haight says. “For our heating systems, we use a low-cost I/O terminal to do the work of several separate components tied together: a temperature controller, a solid-state relay and a thermocouple. This removed unnecessary complexity in our system by eliminating a dedicated controller that needed to communicate with the rest of the system.”
“Semicore continues to have a very high success rate with repeat customers,” Hughes says. “The new machines have been well received and helped increase reorder rates. In addition, several companies using our machines have referred us to their own customers located around the world, so we’ve seen a great boost in word of mouth sales.”
“We saw reductions on the order of 20% in both programming and electrical wiring on our machines,” says Haight. “This helps us reduce machine cost and make custom changes per last-minute customer requests. We can even create new features easily after machines have been delivered and installed on site if needed.”
The new PC-based control system also created a higher end machine without a steep learning curve. “While pushing our automation and controls to new levels, we completely retained user friendliness. You don’t have to be an engineer to operate or troubleshoot our machines,” Hughes says.
|Norm Hardy is a senior process engineer at Semicore Equipment. Contact him by email at email@example.com .|