Alternative Machine Controllers
Alternate CNC choices can offer manufacturers cost and productivity enhancements
By Patrick Waurzyniak
Instead of buying an expensive CNC solution from one of the major machine-tool control developers, some machine shops turn to alternative controllers from machine-tool builders or from third-party control developers. Depending on a shop's requirements, such solutions can offer advantages in customization, costs, or productivity-boosting capabilities that may end up saving manufacturers substantial time and money.
Alternative machine tool controls are offered by a number of machine builders, either as captive or private-brand controls used only on their machines, or via third-party developers' controls that sometimes are retrofits on existing machines. Some alternative controls offer performance said to be superior to major control suppliers' brands, or significant cost savings compared to controls from major suppliers such as Siemens, GE Fanuc, or Heidenhain.
Machine builder Haas Automation Inc. (Oxnard, CA) offers only its own control on its machines. "We do not consider the Haas control an alternate control,” notes Kurt Zierhut, director of electrical engineering, Haas Automation Inc. (Oxnard, CA). "It is the primary control. It is the only one we spend engineering effort interfacing to our machines.
"Our control is designed specifically to run our line of machine tools," Zierhut adds. "It does not contain the overhead and complexity that is required to adapt to hundreds of different machine tool designs. We can build functions into the control electronics and software that are designed along-side the machine itself, while being aware of exactly what the machine 'iron' is doing. At the same time, we do not spend the time interfacing any other controls besides our own to our machines. We only use our own control."
Key technical trends in machine controls include a constant push or pressure for more spindle cutting power, spindle speed, axis power, and axis speed, Zierhut says. Other trends include the need for more control memory, more control speed—or blocks per second—more information displayed on one screen, more networking connectivity to other systems, lower costs, and easier interfaces to pallet systems and robot-loading systems, he adds.
Making its own control gives Haas a number of advantages, notes Zierhut, over manufacturers that must "adapt" someone else's control to their machine. The Haas control is nearly identical on all of its machines, from VMCs and HMCs to lathes. The company also takes full responsibility for the entire machine, Zierhut notes, both control and iron, and if there is a problem, there is no finger pointing at the control manufacturer saying it's a hardware problem, and vice versa.
Open-architecture, PC-based controls represent another step in machine controller alternatives to more proprietary CNC systems developed by major controls suppliers. One such offering is Okuma America Corp.'s (Charlotte, NC) OSP (Okuma Sampling Path) and THINC (The Intelligent Numerical Control) system that it sells to buyers of its machine tool equipment. Last year, the company started its "Partners in THINC" third-party developer program to help develop and build solutions along with partner companies, some of which have personnel located on-site at Okuma's THINC Tank facility in Charlotte.
"Okuma is a large machine control developer," notes Brian Sides, Okuma America engineering director, "we just happen to consume all our own product. Machine and control are not mutually exclusive. Okuma does not consider our control an alternative—just the opposite. In fact, on some machine models, Okuma offers a Fanuc 'alternative,' in addition to our standard OSP offering."
As a global machine builder and CNC developer, Okuma offers the industry a combination of mechanical and electrical technology designed for its products, Sides adds. "This blending of dependent technologies is known as mechatronics and is a key differentiator and technical advantage," Sides states. "The OSP control system is 'tuned' to ensure the optimum performance of the machine tool operation. This tuning goes well beyond the simple but fundamental necessity of having the correctly sized motor and drive system for each application.
"Employing mechatronics principles to develop machine and control in lock-step, Okuma is able to offer functions such as Variable Spindle Speed Threading [VSST], allowing real-time operator adjustment of feed rates while the cutter is in the thread, and our 'thermo-friendly' technologies, which monitor and actually take advantage of all mechanical heat generating sources to reduce process variability and ensure higher machining repeatability."
Productivity and cost improvements often can be realized when manufacturers use alternative controllers developed for specific machine tool equipment. "Eliminating process variability is one example of realized productivity improvement and cost savings," notes Sides. "Another benefit of developing controls with machines is the elimination of 'multisource' service support. When a machine tool is not operating to specification, the determination of 'is it a machine or control issue?' is an irrelevant question to our customer. The customer calls one source and that determination occurs internally at Okuma. If the concern is determined to be control-related, our customer is not redirected to the control vendor for support, thus delaying resolution and costing the customer time and money. Just as a Honda car owner would never be redirected to Nissan to diagnose and correct an engine problem, an Okuma OSP control customer need not ever call another vendor for their control support."
Some key differentiators for Okuma's controls lie in the fact that the controls are developed on a standard industrial PC platform, using industry-wide standards for connectivity and an open application programming interface (API) shared with software developers of machine-tool application programs. "The machine tool is typically the most expensive and highest value-adder in the metalcutting process, while being the least friendly communicator and consumer of critical operations information," Side explains. "Integrating to peripheral factory equipment, such as automation and quality systems, or communicating production information to business systems, has always been unnecessarily difficult and expensive, if not completely impossible, on fully proprietary CNC systems."
As metalcutting customers continue to streamline operations and improve efficiency to remain competitive, they are now demanding the flexibility to which they are accustomed in the office environment be applied on the factory floor, Sides contends. "Intelligent, adaptable machine controls are the answer," he says. "To meet this growing requirement, Okuma developed the latest OSP control system, THINC, which is developed on an off-the-shelf industrial PC platform, which includes Microsoft Windows, Ethernet, USB, and an included control API for software developers. This opens the door to implementing 'plug-and-play' on the factory floor and provides an economical path to future expansion and upgradeability of the control as PC technology advances."
With the THINC control, Okuma customers customize the controller to fit their needs, often independently of Okuma, notes Sides, adding off-the-shelf hardware and developing machine-related PC applications by themselves or third parties, to communicate with the THINC control.
Another alternative controls developer, the MAG Industrial Automation Systems (MAG IAS) Infimatic division (Hebron, KY) introduced its PC-based Freedom NC 200 control in March at WESTEC for the North American market. The Freedom control comes standard with a single-processor architecture using Windows XPe and a realtime kernel, and the system is also offered in an optional multiple-processor mold-and-die package configuration.
"Our focus is on enriching the customer experience, the user experience, so we've designed the controls to be extremely intuitive and easy to use," notes Pete Tecos, Infimatic vice president. "We're also leveraging our technology partners, such as Gibbs' GibbsCAM Shop Floor Programming [SFP] software package, and NextEngine, a scanning system supplier, so we're going to partner with other third-party technologies that complement the control to deliver a better experience to the end user."
The Freedom NC 200 pendant includes a new graphical user interface to give intuitive control of manufacturing processes. Designed to meet the needs of operators on the shop floor, the NC 200 pendant includes: a built-in mouse; mode buttons with LED visual feedback; light-ring buttons for 16 machine functions, 13 pre-assigned and three userdefined; a full command line capability; and Infimatic's VeriCode Advanced NC Editor. The system includes a 32-bit color display for 2-D or 3-D graphics, and the system is waterproof and built to machine-tool standards for fit, finish, and durability in the shop environment.
"In addition to the interface, we designed the whole pendant itself to be something that was very user-friendly to set up," notes Tecos. "We've got a set of function keys here. We've added LED rings so that you can really recognize when something is active." Initially available on Fadal machines, the Infimatic controls will eventually be migrated to the full line of MAG IAS machine tools for applications from simple turning to complex machining on five-axis machines.
For high-efficiency machining, a new control called the Constant Velocity Controller (CVC) has been developed by controls developer Miceli Technologies Inc. (MTI, Essex, Ontario, Canada) that is now available on systems from machine tool builder GBI Cincinnati Inc. (Cincinnati) and as a retrofit on machines from other builders.
Based on an Intel multiprocessor, industrial platform, the CVC control from MTI will be distributed in the US by Velocitech CNC (Independence, KY). The CVC system is said to be capable of simultaneous eight-axis, 50,000-blocks per sec processing speed, making the control an attractive alternative to manufacturers looking to optimize productivity (see "Controller Halves Machine Cycle Time" in the May 2008 Tech Front of Manufacturing Engineering).
The CVC control maintains constant velocity over the workpiece, and sustains a cutting speed that is very near to the programmed speed, enabling a guaranteed reduction in cycle time of 50% when machining complex prismatic parts, according to Carlo Miceli, MTI president. He emphasizes that the 50,000 blocks/sec processing speed is the minimum achieved by the control when interpolating in eight axes; on a three or four-axis system, the CVC is even faster.
"The main thing about our product is efficiency, and that it emphasizes constant velocity," Miceli says. "We never use the term 'high speed.' At this point, I believe the statement has no value to the end user. The term 'constant velocity' is a trademark for us along with the brand."
The speed achieved is in part due to the CVC control's multiple-processor architecture, Miceli says, as well as software algorithms that enable the system's fast processing speeds.
"There is a dedicated processor for every application that is running in the background," Miceli notes. "It is really the entire package that does this. It's a combination of hardware and software."
This article was first published in the July 2008 edition of Manufacturing Engineering magazine.