The two vertical machining centers of the horizontal machining center series are specially designed for the carbide machining of various workpieces in the aerospace and energy industries.

The MTV 1000 and MTV 1250 vertical machining centers of Starrag USA Inc. located in Hebron, Kentucky are five-axis milling/lathes that can provide single-set milling, boring, drilling and tapping, and material turning, such as Ti6Al4V and Ti5553 titanium alloy, nickel-based superalloy and high alloy steel. According to the company, these machines are capable of producing excellent surface finishes on complex and thin-walled parts, and are particularly suitable for aircraft engine housings and gearboxes, as well as oil and gas applications.

MTV 1250 can provide 1,627 Nm (1,200 ft.-lbs.) of torque, and can process workpieces weighing 4,990 kg (11,000 lbs.) and diameters of 2,388 mm (94"). Maximum travel in x-, y- directions The z-axis is 2,184 mm (86 inches), 2,083 mm (82 inches), and 1,880 mm (74 inches). The MTV 1000 provides 949 Nm (700 ft.-lbs.) of torque and can handle up to 3,000 kg (6,613 lbs.) .) Workpieces with a diameter of 1,880 mm. The strokes along the x, y, and z axes are 1,702 mm (67 inches), 2,083 mm, and 1,880 mm, respectively.

MTV 1000 and MTV 1250 VMC can handle hard metal milling and turning. Image courtesy of Starrag

Thanks to the all-gear a-axis spindle drive, both machines can achieve high metal removal rates. According to Starrag, since the distance between the nose of the spindle and the a-axis is the smallest, the design allows the use of short tools and large bearings, and has higher stability and rigidity compared to traditional electric spindles.

"The a-axis is essentially a huge lever," said Tim Mooney, director of North American sales. "By keeping it short, you can get the maximum holding force at the tip of the tool because the leverage effect is greatly reduced."

The a-axis is also equipped with a steel worm gear. He said the toughness of steel gives this gear an advantage over traditional bronze gears, which tend to loosen over time when cutting hard metals. The gear also provides active damping for hard metal machining.

In addition, Mooney pointed out that the all-steel gear set of the machine tool spindle is a sturdy mechanical transmission designed to withstand the forces generated when cutting hard metals, which provides them with a decisive advantage over electric spindle transmissions.

"We have a five-year warranty for the spindles on these machines, while the motorized spindles usually have a one-year warranty," he said.

Another key feature is a 30-horsepower angular automatic head, which allows access to internal surfaces and features. The tool head is automatically loaded from the tool magazine.

Using angle heads, these machines can cut the internal and external features of aerospace engine shells.

"We can load a right-angle tool head and mill or drill features in the casing perpendicular to the centerline of the spindle without changing the part settings," Mooney said. "So you can reach places that traditional spindles can't reach."

For turning, the machine can provide 207 bar (3,000 psi) of coolant. In addition to helping to ensure proper lubrication for a good surface finish, he said that high-pressure coolant can also be used as a chipbreaker to prevent the formation of long chips that are common in turning operations.

Both machines are equipped with Siemens 840D CNC. Like other machines in the STC series, these VMCs only provide Siemens control systems. Mooney admits that this may be disadvantageous for stores that prefer other companies to control.

Like other STC-MTV machines, MTV 1000 and MTV 1250 can be used as stand-alone devices or integrated into a cell or flexible manufacturing system. Integrated with other Starrag machines, they can use centralized tool handling and pallet storage. They can also be connected to other processes such as cleaning, deburring, part marking and coordinate measurement.

Mooney believes that the biggest challenge facing the machine is the processing of composite materials, but it is not because composite materials are difficult to cut. Instead, the challenge is to deal with the dust generated when processing composite materials. For example, the machine must be properly sealed to prevent dust from entering and damaging parts such as the scale.

"It is important to determine the material to be cut from the beginning," he said. "But these machines can be configured for almost any application."    

William Leventon is a contributing editor of "Cutting Tool Engineering" magazine. Contact him by phone 609-920-3335 or email to wleventon@gmail.com.

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