ROUTINELY ACHIEVE 4µ MACHINING PRECISION AND ACCURACY

These four- and five-axis horizontal machining centers are ideal for aerospace machining of exotic materials with hard-to-machine characteristics, such as titanium and Inconel.

StarragHeckert and SIP (Geneva, Switzerland) have combined the benefits of intelligent German engineering with the time-honored Swiss precision of SIP. The result is the SPC (Super Precision Center) Series SIP 4/5-axis horizontal machining centers that feature a compact design, highly productive tool and workpiece handling and are ideally suited for a broad spectrum of production applications, while routinely achieving 4µ precision and accuracy (according to VDI/DGQ 3441). The SPC has selectable process adaption parameters automatically optimizing machine performance depending on roughing, finishing and fine-finishing operation requirements.

SPCs are well suited to the precision machine industry, where key part tolerances have an effect on the overall achievable accuracy of the complete machine system. The SPC Series SIP meets the manufacturing requirements of the industry demands for quick set-up times, fast change over and rapid chip-to-chip times.

Today’s aerospace companies are faced with the demands of machining exotic materials with hard-to-machine characteristics such as titanium and Inconel. These manufacturing challenges are further compounded when precision bores and dimensional shapes require machined tolerances in the single-micron range. The SPC Series SIP is specifically built to meet these demanding applications. The high-precision machine design and “best-in-class” geometry works in tandem with the machine’s high productivity features. The result is highly accurate parts produced in volume with high accuracy.

These HMCs feature hand scraping of critical contact surfaces (guideways, contact pads of ball screws, spindle and axis) providing smooth, accurate and repeatable operation. Super precision is assured by utilizing complete temperature control throughout. A thermo-symmetrical machine design with all heat sources isolated controls precision deviation. This maintains super precision of the complete machining system. The machines are equipped with horizontal spindles, along with a large chose of system options offering complete scope enabling the customer to specify a machine ideal for the most demanding of applications.

The high-precision horizontal main spindle combined with automatic elongation control provides the power and precision for complete process performance. The variable AC 50 kW main drive motor delivers speeds up to 15,000 rpm, combined with the machine’s rigidity, this provides the basis to remove metal at high rates, cutting C45 steel at 1,800 cm³/min. The customer also has a choice of either HSK-A 100 and ISO 50 spindle tapers. Linear measuring systems made of steel are used for axis position control. The resolution of the measuring scales is specified at 0.1µ. The thermal expansion coefficient of the measuring scales is constant to the expansion and contraction rates of the machine.

The new direct-drive NC rotary table with absolute angle measurement technology offers unparalleled levels of precision capability while machining complex features and multi-sided workpieces. Incremental precision of 0.0001 deg and rotational speeds of 25 rpm are standard. Automatic monitoring and adjustment of acceleration of the rotary axis based on workpiece mass is standard. Twin pallet automatic load/unload for increased productivity comes as standard with pallets up to 630 x 630 (800) mm (SPC 7120) and 800 x 800 (1000) mm (SPC 7140).

The automatic tool changer (ATC) is designed for reducing non-productive idle times. The chain magazine has 60 (80 optional) tool pockets for tools up to 325 mm in diameter, 600 mm in length, and individual tools weighing 28 kg. For higher tool requirements the SPC SIP can be equipped with tower magazines for 180, 240 and 320 tools. Temperature control is maintained with a cooling system equipped with a differential temperature controller, this ensures super precision on the work piece throughout the machining process.

The machine tool is equipped with either the Siemens 840 D or Fanuc 31i CNC control system. The SPC 7120 SIP travel values are 1,200 mm in X, 950 mm in Y and 1,200 mm in Z. (7140: 1450 mm in X, 1100 mm in Y and 1300 in Z.) Working feed rates are up to 40 m/min (X, Y and Z), while rapid traverse rates are 40 m/min in all three axes. Rapid traverse rate of the B-axis is 25 U/min. Acceleration rates are 3.5 m/sec² in X, Y and Z axes. Accuracy of linear axes: positioning deviation of < 0.004 mm; repeatability of < 0.002 mm and maximum backlash width U max of < 0.001 mm.

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