THE SUPER-NURBS DIFFERENCE
Super-NURBS is able to deliver the fastest speeds and highest quality finishes in the industry. This is due in part to its foundation in the mechatronics approach, Okuma’s blending of mechanical and electrical development to assure optimized communication between the machine and its control. Super-NURBS also delivers the following unique benefits:
- Faster Control Loops Speed: The feedback loop determines how quickly the CNC machine can “talk” to the encoder and servo units. With Super-NURBS, the machine is faster in telling the servo where to move, and in receiving confirmation of getting information, allowing for more ultra-high feedrates to be used. At times, this can involve “talking” to as many as five servos simultaneously. [Graphic: Video] [Caption: Super-NURBS completes a part that typically took 55 minutes in 30 minutes, while maintaining a highly accurate finish.]
- Digital-to-Digital: While controls are digital, many machine tools in the industry still use analog. This requires translation activity that slows down the CNC machining process. With Okuma machines outfitted with Super-NURBS, the control loops feed is digital-to-digital, which speeds up the communications process and therefore allows for faster machining. There is no need for a look-ahead within a Super-NURBS system because it’s inherently fast without it.
- Machine Build Quality: Okuma delivers the complete package of machine and control. The build quality of Okuma CNC machines enhances overall functionality, with features including: ribbed castings for strength, large base casting with three-point leveling, integrated ballscrew mounts to ensure rigidity, cantilevered column to reduce weight and resist bending, handscraped cast mating surfaces for superior flatness and contact, and a work area enclosed in sheet metal to eliminate hot chips and coolant from contacting castings, which minimizes thermal influences.
IMPACTS FOR THE CNC MACHINING ENVIRONMENT
With complex curvature shapes, a CAM system will output a series of X, Y and Z points (in a 3 axis example). It will create the curve using piecewise linear movements. Therefore, in order to generate a curve, it will actually utilize many small linear movements. When left in that form, as part of the feedback processing loop, the CNC control will attempt to drive to each individual point and ask for confirmation if it made it to its intended destination. The CNC machine may never reach it’s programmed speed because it can only crunch so much data before it has to start slowing down to maintain the feedback loop and keep the programmed accuracy. This is something machinists and programmers have no control over, the machine control makes the decision on how fast it can go while maintaining the point-to-point accuracy of the shape.