Custom CNC is at heart of groundbreaking laser cutting machine

Customized CNC technology from NUM is helping the laser cutting machine manufacturer Favor Laser to accelerate product development and address new markets. Using special hardware and software designed by NUM, the Taiwanese company has developed a high precision laser cutter that is equally capable of producing very small or very large parts from sheet metal, with a cutting feed rate of up to 60 meters per minute.

Until now, Favor Laser has concentrated on producing laser cutters for the low cost end of the market. In 2010, it began developing a high performance multi-capability laser cutting machine for the international market, which is currently dominated by a small number of Swiss, German and Japanese manufacturers. By combining its laser cutting technology with value-engineered hardware and advanced CNC software, the company anticipated it could produce a machine with the same performance as the market leaders, but at significantly lower cost.

All Favor Laser machines are based on an innovative flying optics system, where the metal sheet that is being cut is supported on a stationary table, and the cutting head which directs the laser beam is moved horizontally above the surface of the sheet. The company’s new XO high performance laser cutter is a four axis machine, but uses two motors for the X axis. Horizontal positioning of the cutting head is controlled by the X and Y axes, which have working lengths of 3 and 1.5 meters respectively; this large working area, combined with an X-Y positioning accuracy of ±0.01 mm, helps maximize machine versatility.

To maintain beam focus and cutting efficiency, the gap between the cutting head and workpiece is continually monitored and adjusted using a high speed servo on the Z axis. The X, Y and Z axes are fully interpolated to ensure smooth and continuous motion control, while patented adaptive optics compensate for the length of laser beam, which varies depending on the position of the cutting head relative to the laser oscillator. The machine’s fourth (U) axis handles material loading and unloading.

After investigating various CNC options, Favor Laser chose NUM’s Flexium 68 system for its new XO machine. The CNC system’s motion control hardware closely matched requirements and provided configuration flexibility for future enhancements, and its software functionality would simplify application programming. In particular, the ‘Dynamic Operator’ function – which is unique to NUM – was judged ideal for the program that dynamically controls the gap between the cutting head and the workpiece. Using fast calculation and communication facilities, the function enables event-driven machine cycles to be integrated into the real-time CNC kernel.

According to Favor Laser’s General Manager, Mr. Lai, “We were delighted to discover that NUM Taiwan had the engineering expertise, resources and willingness to assist us at every stage of design. Thanks to their help, which included developing custom hardware and CNC software, we have been able to bring our new XO high performance laser cutter to market on time and to budget. As a result of reduced development and build costs we have gained an enormous competitive advantage. Our machine is likely to be priced about 20 to 30% below comparable machines from Japanese and German manufacturers.”

All motion control elements of the XO laser cutter are supplied by NUM. In addition to the motors, NUMDrive C servodrives and Flexium 68 CNC kernel, the machine uses NUM Ethercat I/O terminals and a dual-processor Flexium FS152i operator panel with a 15-inch flat screen and hard drive. The custom human-machine interface (HMI) was developed entirely by NUM Taiwan and makes extensive use of graphics – including visualization of the workpiece and cutting course – to simplify machine operation and minimize training needs.

Operating conditions can change abruptly during laser cutting, demanding quick adjustment of a large number of parameters to ensure consistent performance. Controlling the laser oscillator’s power output is a particular design challenge, and requires extremely fast and stable communication facilities. To meet these demands, NUM Taiwan developed a special pulse train control card for the CO2 laser oscillator in the XO machine. Implemented entirely in hardware (the use of software would impose unacceptable timing restrictions), the card translates duty cycle and frequency control signals, which are optically coupled to the oscillator to minimize transmission delay.

The performance of NUM’s CNC products and the responsiveness of NUM Taiwan has caused Favor Laser to completely re-evaluate its machine control strategy. The company now intends migrating its existing product lines over to Flexium systems, and to base future machines on NUM’s CNC technology. As Mr Lai explains, “I am confident that our partnership with NUM places Favor Laser in the best possible position to create new laser cutting machine solutions that will benefit our customers.”

(September 2013)