Assessing machine tool controls
by Tim Wilson
Controls on machine tools can now do more than ever. Perhaps equally important, they are also more flexible. As a result, there are a variety of ways both machine tool builders and customers can approach the market for controls.
“The machine builders have to decide if they want to buy their controls – either from a brand name company or a generic, off-the-shelf supplier—or if they want to develop their own controls,” says Vince D’Alessio, executive VP, Elliott Matsuura Canada Inc., Oakville, ON.
Elliott Matsuura has gone with two control suppliers: Fanuc and Siemens. Another major player is Heidenhain.
“If you look at the major players, Fanuc, Siemens, Heidenhain, you then have to decide what control meets what criteria, and what you want the machine to do,” says D’Alessio. “Will the machine be turning? Milling? High speed milling? Five axis?”
D’Alessio says Elliott Matsuura offers both Fanuc and Siemens because, though in five axis environments Siemens is “a bit more powerful,” Fanuc is nonetheless more dominant in production machining.
“We want to give the customer the option to put the control of their preference on the machine,” he says. “But if you look at turning and milling, these are more generic manufacturing processes, and typically a customer will go with an off-the-shelf control system developed by a manufacturer.”
Then there are unique circumstances that demand a specific approach.
“There could be a number of reasons why a machine tool builder might gravitate toward one control or another,” says D’Alessio. “For example, Matsuura makes a machine that has five axis milling and turning on the same machine. It needs a specific motor from Siemens, and therefore has to use Siemens’ controls, too.”
Beyond the machining design, a machine’s intended purpose will clearly determine the best control system. Some are highly specialized.
“EDM [electrical discharge machining], metrology, water jet, grinding, laser cutting—these machine tool builders will go through their own development, because they want unique features for those processes,” says D’Alessio.
For companies who build controls for machine builders, the way to add relevance to a control system is to go after the cutting edge, high demand application environments. This is true for Heidenhain, which is active in the high speed machining market.
“Milling machines, boring mills —we specialize in that area and are very popular on those types of machines,” says Scott Warner, regional manager at Heidenhain in Toronto. “But we are now also on the forefront of high speed machining and the technology that surrounds it.”
Warner argues that one of Heidenhain’s advantages is that it looks beyond the control system to include all the various aspects of machining. In effect, speed is only of any use if it ensures accuracy and quality.
“There is a lot more to a control system than having it run fast,” says Warner. “There are a lot of little applications – both hardware and software – that are needed to get the machine running.”
Fagor Automation, the largest employee-owned company in the world, prides itself in being able to address complex requirements, and to work with any vendor.
“We make controls for all types of machines—milling, turning, grinding, punching, metal cutting and fabrication, plasma cutting, laser cutting,” says Harsh Bibra, general manager of the North American division of Fagor, Mississauga, ON. “Part of the increasing complexity is the need to combine more than one operation on a machine. For example, you might need to bend and drill holes, to combine laser cutting and punching, or put more emphasis on milling than turning. We can do that.”
In such scenarios, more than one independent information channel is coming into the CNC. Fagor can deliver to a high level of flexibility; its 8065 CNC, for example, is able to take up to four channels.
“Five axis machining is complex,” says Bibra. “As a result, a control has to process a lot of data to ensure finish and accuracy. The processing power has to be to less than half a millisecond.”
To achieve this, Fagor has unique algorithms that address the need for adaptive, real-time speeds and feeds, with the ability to monitor the spindle load and the tool temperature to ensure the best finish.
On the other side of the discussion are the builders themselves. These companies, of which Okuma is a prime example, make a compelling argument: that the software driving a machine should be developed by the people who best know the machines.
Okuma’s THINC intelligent control runs on a dual core high speed processor. It can interface via USB and Ethernet to Okuma’s THINC-API to communicate with bar code scanners, barfeeders, robots, probes and tool setters.
“Our new P300 CNC control, which is an advance on the current P200A model, is designed to simplify the user interface,” says Brian Sides, director of technology at Okuma.
The P300 CNC control has improved tool data management, with information consolidated in one database.
An Okuma control system address collision avoidance in demanding environments. A 3D Virtual Monitor runs a model off-line to ensure that things go smoothly in real-time. “Our collision avoidance software runs on the machine, and can work in either an automatic or manual mode,” says Sides. Given that Okuma works with a range of companies, its platform has to be based on an open standards.
“The Partners in THINC program has over 40 partners since forming in 2007,” says Sides. “We’ve been working to improve the user experience, to get the devices talking to one another, sharing data from different places.”
Though Okuma’s control technology is designed for its machines, the company works with the MTConnect manufacturing industry standard. “It means that THINC can grow and adapt, unlike other CNC approaches, in which the technology is frozen in time upon delivery,” says Sides. SMT
Tim Wilson is a freelance writer based in Peterborough, ON.