Designed specifically for precision mold machining, Hyundai Wia’s Hi-Mold series of high speed VMCs offer a rigid bridge-type design that is said to minimize heat generation. Features include spindle speeds ranging to 40,000 rpm, through-spindle coolant and simultaneous five-axis machining capability.
All axes employ double-nut ballscrews with a double pretension design. This provides high positioning accuracy and repeatability with virtually no thermal growth, the company says. To eliminate backlash, ballscrews are connected directly to the servo drive motors without gears or belts. Linear motion guideways provide rapid traverse rates of 50 m/min in the X, Y and Z axes and 70/150 rpm in the A and C axes.
With a built-in drive, the HSK-A63 main spindle offers 24,000 rpm, an output of 33/25 kW and 96/72.5 Nm of torque. Angular bearings provide rapid acceleration and deceleration as well as smooth machining at high rpms, the company says. Users can also opt for a 40,000-rpm spindle to improve the quality of mold bases and cavities. A spindle oil chiller ensures constant oil temperature and minimizes spindle growth from heat distortion, the company says, while through-spindle coolant (20, 30 and 70 bar) is said to decrease heat generation for improved machining stability and tool life, especially for deep-hole applications.
A shutter system that closes during machining protects the machines’ ATC and magazine from chips and cutting fluids. The ATC accommodates 24 tools (30 on the Hi-Mold 750/5A) with maximum diameter of 120/140 mm (20 mm at 40,000 rpm), a maximum length of 300 mm (100 mm at 40,000 rpm), and a maximum weight of 8 kg (1.5 kg at 40,000 rpm). Tool change time is 2.6 sec.
The machines’ rotating and tilting table enables cutting a variety of complex shapes. C-axis rotation is 360 degrees at 150 rpm, and A-axis rotation is 150 degrees at 70 rpm. Each rotational axis has a hydraulic clamping system and roller bearings for stiffness and precision. Tilting angle is +30 to -120 degrees, and the minimum directive angle is 0.001 degree. The worktable can accommodate 250 kg.
Options include a choice of a Siemens Sinumeric 840D or Fanuc 31i-A CNC, a spindle probe for setting workpiece coordinate values, a tool setter for setting tool lengths and diameters, and linear scales for improved positioning accuracy.
Cryogenic machining achieves dramatic tool life gains not by flooding the cut, but by refrigerating the tool.
At IMTS 2014, you’ll see that a familiar U.S. machine tool brand is back.
The recipe for best results is simple: Start with a rigid machine, add a high pressure through-the-spindle coolant system, then combine these with the right drill geometry plus the right speeds and feeds.