Taking Control
Haas makes machine controls its own way

Thomas Tennant, Contributing Editor

Haas CNC Control

In 1987 the engineers at Haas Automation were facing a dilemma of sorts. The Oxnard, CA-based company was developing a new CNC vertical machining center it planned to unveil at IMTS '88, the premier biennial trade show for the machining industry. This machine, the VF-1, would be built from the programmer's and operator's viewpoint. It would be new and it would be different and it would be made the Haas way. But when it came time to add machine controls, the design engineers were quickly coming to a disappointing conclusion. "We couldn't afford it," reflects Kurt Zierhut, Haas's manager of electrical engineering.

At the time, the machine control market was largely controlled by Japan and Germany. The cost per machine was around $20,000, an expense the company could not justify at the time.

"Haas was feeling a bit like an underdog," says Zierhut. "And then we really started thinking maybe the easiest thing was to just build our own." It seemed like a relatively difficult choice to make. Haas would have to ignore the voices of consultants telling it it had to choose this or that company because this or that company was setting the standard in the machine control world. Those voices were, in effect, telling Haas if it tried any other way, it would be sunk before it set sail.

To which Haas's response was Damn the torpedoes, full speed ahead!

When the company started building its own controls, there was one machine tool programmer who had some strong opinions about how the controls should be -- Gene Haas, president and founder.

"There were certain things about everyday controls that he just hated," says Zierhut. There were several chapter buttons on one machine control in particular, and returning to the previous chapter, or action, proved to be difficult and time consuming. Mr Haas made a pledge that his controls would be simpler.

"We decided that by building our own, we could give the machine a personality specific to us," continues Zierhut. "We also took -- and still take -- into account the human factor; how software interacts with people and people interact with software. We had used existing controls, and we vowed to make it easier."

During the design process, Haas realized that every aspect of creating its own machine control was a difficult task. But obstacles were few and far between -- Zierhut recalls the process as "smooth" as far as development was concerned. Haas had proved it could be done when it unveiled the VF-1 at IMTS '88, and continued to do so since then.

Making it easier

Haas is both a manufacturer and a design house. Because of that, production takes on an holistic approach.

Remote jog controller

Engineers live with a constant duality -- to be both designers and manufacturers. As designers, they know which functions will and will not work when building machine controls. As manufacturers, they know which design functions are most important to the operators. The CNC system is designed and built specifically for Haas machine tools, says company literature. The control system uses dual Motorola processors and has 1 Mb of 20 nanosecond, high-speed static RAM on a 40 MHz bus to provide up to 1000 blocks-per-sec of program execution speed standard. This allows servo loop calculations to be performed 4000 blocks/sec for each of six axes. Additionally, static RAM options of up to 16 Mb retain memory changes instantly and permanently, whereas a PC's dynamic RAM only retains memory while power is applied.

Keyboard standardization is an important element, as well as use of the same CNC control, observes David Hayes, product manager-VMCs/HMCs. Much of it is about single stroke vs. multiple stroke functions. With the exception of a few keys that are lathe-/turning center-specific, if someone has learned how to power up and program one Haas machine, he or she can run just about anything Haas manufactures.

"For example," explains Zierhut, "go up to any machine and count how many keystrokes you have to make to start the machine; then get the machine powered up and ready to go. Last time I counted on (one particular machine control) it was nearly 27 keystrokes. You can start ours in only three presses."

HSM, Ethernet

"A lot of it is still there, as far as keystrokes," says Hayes, "We've continued to add features, such as speed. One of the latest advances for us is high-speed machining."

As described on the company's website, "The new high speed machining option for Haas VMCs and HMCs helps reduce cycle times and improve accuracy for 3-, 4-, and 5-axis parts. Testing on complex mold applications has shown a reduction in cycle time of nearly 2/3 while providing improved accuracy and smoother motion.

"Using a motion algorithm called acceleration before interpolation, combined with full look-ahead of up to 80 blocks, the option provides feedrates up to 500 inches per min. without risk of distortion to the programmed path. Combining the algorithm with Haas's Extra Rapid Traverse (XRT) option -- which uses high-pitch ballscrews -- will provide rapids to 1200 ipm and cutting feeds to 833 ipm. All programmed motions are accelerated before interpolation, which ensures that the movement of each axis does not exceed the acceleration capability of that axis, the literature explains. The look-ahead algorithm determines the fastest feedrate at which one stroke can be blended into another without stopping. The result is higher accuracy, smoother motion, and a higher actual feedrate, even with complex geometry.

"Haas high speed CNC software controls machine motion for both low and high feedrates by building a queue of motion strokes from axis-motion data found in the G-code program. The look-ahead function then determines the maximum velocity that can be maintained at each stroke junction. Junctions of linear strokes with very shallow blending angles, or circular strokes that are tangent to the velocity vector, require no reduction in velocity and can be negotiated at the maximum programmed feed-rate," the literature says. "Stroke junctions with greater angles are negotiated at lesser velocities.

"For very fast feedrates up to 500 ipm, and very short command block stroke lengths, the option looks ahead as many as 80 blocks to find where velocity must begin deceleration to be slow enough for a sharp corner or exact stop.

"At low feedrates, or when executing long command-block stroke lengths, the look-ahead distance may only need to be one or two blocks. Part accuracy is specified through a setting or the G-code program using the contour accuracy control feature. This allows the user to define an accuracy value for the overall part, as well as higher accuracies for specific areas of the cutting path. Improvements in cycle time are possible with the control planning the acceleration profile over many motion blocks instead of dealing with individual blocks. Accuracy is also improved because the abrupt changes in direction are visible far enough ahead of time to compute the required acceleration necessary to bring velocity down to a value appropriate for the direction change."

As another example of Haas' commitment to operator ease, the option accepts ISO standard G-code from all major CAM systems. A number of high-speed controls require a pre-processing mode or special post, which can be time consuming and alters the G-code program. Another new feature from Haas is its ethernet control option, which allows the machine shop to network its Haas brushless CNC machines. The option consists of an embedded processor in the control with an ethernet interface that allows the control to access the machine shop's local ethernet system using industry standard 10 base-T wiring and RJ-45 phone-style connectors. The benefit: access to the company's local area network and nearly unlimited quantities of G-code programs.

Future

Every year since creating the first Haas control system, the company has reevaluated whether to buy or build machine controls. When it looks at the cost, the conclusion is the same as it was in 1987.

"They're still more expensive than what we can consider," remarks Zeirhut.

So the company keeps plugging along building its own controls. "At least a handful or more people say to me each year that I can't survive unless I use their controls, or that I'll miss out on the wave of PC-based controls," says Zierhut, speaking of software that can turn a standard PC into a CNC control. "We've avoided that wave for several years because we don't believe there is a wave."

Success for Haas is evident in the number of machines it sells. Haas has sold more than 32,000 rotary tables and 24,000 machining centers. They have shipped more than 550 CNC machines per month and have the capacity to ship 20% more.

"Other companies say we have to use their controls because they define the standard," says Zierhut. "They don't define the standard. We define the standard."

For more information:

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