Laser, Waterjet, Plasma Cutting Systems

PLUG AND PLAY LASER MACHINING
Proteck Machinery Pvt. Ltd. (Chennai, India) was established over 25 years ago and is now one of India’s leading production machinery suppliers, distributing, supplying and manufacturing a wide range of printing machinery, machine tools, metal cutting and forming equipment, and CAD/CAM software throughout its home market and in more than 20 countries world-wide.

Its manufacturing subsidiary, Proteck Precision, has a young, dynamic and highly qualified engineering workforce that develops and produces exciting new economy solutions for the fast growing Indian manufacturing industries as well as providing competitively priced machinery that is exported beyond Asia. This technology-driven company has styled its production, quality control and engineering logistics departments on a European model and has two very modern manufacturing facilities in Chennai, complete with state-of-the-art CAD/CAM, MRP systems and the latest ISO accreditations.

This Indian equipment supplier began working closely with Kollmorgen Europe GmbH (Ratingen, Germany) after experiencing their impressive servo motor and drive performance and reliability in some of the German CNC machine tools that Proteck was distributing into its own markets. Kollmorgen has provided integrated automation and drive systems, along with corresponding components, for machine builders all over the world for more than 70 years. A learning curve and close relationship progressed with product training and close application support from their European-based engineering facilities and further support from its Mumbai-based team.

Proteck engineers have had extensive training at the Ratingen facility, and as they develop their own ProLaser CL purpose laser cutting and CNC machine tool range, Kollmorgen is very firmly established as a manufacturing partner. “Our latest generation laser profiling and machine tools have developed from more than two decades of experience in supplying and supporting machine tool technologies from our partners, as well as from our increasing in-house design and manufacturing capability,” says Mr. K. Bala, the managing director of Proteck. “In both of these important factors, we count Kollmorgen as a major technology contributor and a valued partner.”

Proteck began manufacturing high specification CO2 equipped 3-axis laser cutting systems with flying optics that cater to a wide range of flat sheet material. These small footprint machines originally included cast-iron beds and single lower-axis geometry that allowed open three-side access for flat sheet sizes around 2.5 m x 1.5 m. Bosch Rexroth or Siemens CNC controller options fully integrated with highly developed MetaCAM CAD/CAM software allows ease of use for all types of sheet metal cutting.

The company then introduced a ‘Plug and Play’ model for job and fabrication shops that included all of the features of the previous machines, but used a much lighter and lower-cost welded-frame construction. This began its ground-breaking marketing concept that a laser cutting machine should be no more complicated than an office laser printer.

As part of this continued initiative, designers looked hard at the transmission mechanics. Precision ground ballscrew cost for a 2.5 m travel range is expensive and the single-axis/single-screw design with its overhung load requires more sturdy and costly linear motion guide bearings for adequate support. Furthermore, to maintain a good dynamic performance, ballscrews must be large in diameter to allow high rotation speeds – which increases servo motor and servo drive size. With the need to produce even longer travel machines that could provide larger flat sheet work, Proteck and Kollmorgen EU began to address some central questions:

•  How to maintain the ±10 micron bi-directional repeatability performance and up to 110 m/min max linear speed, required of the machines?
•  How to reduce the power requirements and provide increased efficiency?
•  How to further drive down powertrain component costs?

The result was the introduction of an innovative rack-and-pinion drive system for the long-travel lower axis of the machine for a new 3-axis bridge laser machining center that includes two synchronized lower X-axes, supporting a gantry Y-axis, and a vertical Z-axis.

Rack-and-pinion with direct drive motor and innovative preload
The initial conception looked at linear motor technology for the long-travel dual synchronized X-axis, but the cost for this was prohibitive for the market sector being targeted for the machine. The cost effective rack-and-pinion design was developed with the awareness that backlash and repeatability performance would need to be achieved using a novel approach.

The special preload mechanism was realized by mounting the pinion and its motor on an eccentric pilot circle and a gear tooth geometry that allowed full face gear contact and in-situ adjustment to minimize lost motion and hysteresis. This performed more than adequately at the point of the actual rack-and-pinion face – but when combined with a standard rotary servo motor which required a planetary gearbox to develop the torque required to drive the load – the gearbox backlash, albeit relatively small, proved prohibitive.

The answer was to design the pinion-to-rack transmission around the Kollmorgen KBM series direct drive motor.

Directly coupled
The KBM separate rotor and stator packages are supplied in kit form and directly mounted on the machine by Proteck within their own bearing system and protective cover, with power and encoder connectors built-in. The mounting arrangement directly couples the large diameter pinion shaft to the rotor as a single solid assembly, restricting lost motion and potential unwanted harmonics that a flexible coupling may give rise to.

The resulting design has been field proven for extremely low backlash and has a dynamic and throughput specification which is very close to linear servo motor performance. This rack-and-pinion system is also very resilient to debris and does not require the degree of protection that a linear motor system would need for a laser machining environment.

This rack-and-pinion system, combined with the direct drive KBM motors, uses less parts, is more energy efficient, and delivers higher speed and accuracy to reduce backlash and lost motion well below the desired specification. As an intrinsic part of the design, S700 servo drives with their multi-feedback capability are used with both resolver feedback, mounted on the KBM motor for commutation, and magnetic linear scales for the position loop. The feedback protocol is SSI absolute, EnDAT or alternatively BiSS, to suit a choice of CNC controllers with set-up and monitoring via EtherCAT that is integrated in all S700 drives.

Many optional features of the advanced servo drive may be included in the machine specification. These include STO (Safe Torque Off) for SIL 2 and 3 safety standards, and Ethernet connectivity for set-up and monitoring. EtherCAT is also available and will be integrated in future machines for axis synchronization. With a maximum sheet size of 3.1 m x 1.6 m, next-generation ProLaser CL flat sheet cutting machines also use AKM series rotary servo motors with Micron™ series planetary gearheads that are brake fitted for the Y-axis as well as the Z-axis.

For complete compatibility, S700 drives are used throughout the machine, which will also benefit in the future from a cost-optimized CNC control solution from German cutting machine specialist Eckelmann AG (Wiesbaden, Germany), which works closely with Kollmorgen EU.

Direct drive offers further advantages
The latest Proteck laser cutting machine, the Sl 2530, is a massive 7-axis ‘walkin’ machining center which includes an advanced flying optics head design that provides laser cutting of vertical and angled sides of formed workpieces. Large three-dimensional fabricated sheet metal workpieces are fixed to a stationary central table and the multi-rotational laser head is guided to always maintain the optimum perpendicular angle for perfect cutting.

KBM direct drive motors with the innovative rack-and-pinion mechanism are used for main horizontal axes of the machine, which covers an area of 1.6 m x 3.3 m x 0.7 m. The hollow-shaft KBM motor is also used as the main drive for the multi-rotational flying optics system, allowing feed-through of the laser delivery and focusing system while maintaining the flexibility and precision to provide completely synchronized twin rotary axes, featuring nX360 deg and ±135 deg rotational strokes. The machine also uses a complement of AKM servo motors on other axes along with matching S700 drives, allowing users to reduce spares and inventory costs.

Proteck Machinery Pvt. Ltd., 15 Medavakkam Road, Sholinganallur, Chennai 600 119, India, + 91 44 2450 6000, Fax : + 91 44 2450 6006, [email protected], www.proteck.co.in.

Kollmorgen Europe GmbH, Pempelfurtstraße 1, 40880 Ratingen, Germany, +49 2102 9394 2195, [email protected], www.kollmorgen.com.

WATERJET CUTTING

TAPER-FREE CUTTING IN WATERJET MICROMACHINING
With its MicroMAX JetMachining Center, OMAX® Corporation (Kent, WA) proves how the speed, versatility and accuracy of abrasive waterjet technology now applies to the cutting of micron-level parts or part features from a wide range of materials, including exotic metals, advanced composites, polymer thermoplastics and glass.

Ideal for prototype development and production runs, the MicroMAX is a highly rigid machine with a table size of 2 ft 4 in by 2 ft 4 in and an X-Y cutting travel of 2 ft by 2 ft. It utilizes advanced high-precision linear encoders, innovative vibration isolation and intuitive software control systems to achieve a position repeatability of less than 3 microns and a positioning accuracy of approximately 15 microns (0.0006 in).

The MicroMAX comes equipped with a high precision 7/15 Mini MAXJET® 5i long-life diamond integrated nozzle that features a 0.007 in orifice and 0.015 in mixing tube combination for quickly and accurately cutting delicate, complex patterns. Because it forms a jet stream carrying an extremely fine abrasive, the nozzle can produce a kerf as small as 0.015 in. The machine also has advanced pressure controls for piercing delicate materials.

Now, a smaller version of the award-winning Tilt-A-Jet® cutting head designed specifically for MicroMAX JetMachining Centers is the new Mini Tilt-A-Jet® cutting head that nearly quadruples position accuracy for even more precise cutting. The position accuracy of the nozzle enables the machine to achieve virtually zero taper with most materials up to 3 in thick. It is also 25 percent smaller and lighter than the Tilt-A-Jet and is nearly twice as rigid for less deflection. The Tilt-A-Jet for the MicroMAX employs 10 deg of tilt and is fully sealed for use in the abrasive waterjet environment.

The MicroMAX is a flexible, cost-effective and beneficial alternative to conventional machining operations.  Because waterjet-based machining is a coldcutting process, it eliminates thermal stress in the workpiece, preventing hardening and warping. The MicroMAX enables manufacturers across all industry segments to accomplish quick turnaround of accurate parts without the hassle of tool changes or complex fixturing, as well as achieve smooth surface finishes without the need for secondary machining.