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Variable-Speed Machining Just a Tool Change Away

Variable-Speed Machining Just a Tool Change Away

A variable-speed VRT spindle machines an EDM electrode at 30,000 rpm.

Multi-tasking functionality, as of late, has become quite the mantra for machine tool developers. These types of machines can potentially deliver productivity increases in the neighborhood of 400 percent.

However, they can have a drawback when it comes to spindle performance.

Multi-tasking machines perform a variety of different operations — from turning and milling to tapping and boring — that require specific spindle speeds and torque capabilities.

The problem is that some machines come with high-speed spindles that don’t have the torque for low-speed work, and others have low-speed spindles that can’t do high-speed work. The solution to the problem could be as easy as making a tool change.

VRT variable highspeed multi-tasked spindles from Bryan Machine Service Inc. ( work like any other tool in a machine’s tool changer, completely unattended.

The spindles, when interfaced with a machine’s existing controls, eliminate the need for separate spindles for each speed to be run.

The spindles’ variable speeds can range from 15,000 rpm to 40,000 rpm, enabling machines with lower spindle speeds to now also perform high-speed work and those with high-speed spindles to do low-speed work. Both scenarios are accomplished using the same spindle.

Spindle speeds of the VRT are externally adjustable and selfregulating, and multitasking machines equipped with them can often completely machine parts on their own.

Part costs are lower because fewer spindles are needed, part handling for multiple setups is eliminated, and one tool can apply to a wider range of applications to minimize inventory and even machines themselves that shops keep on hand. Since one VRT spindle can machine a range of materials, they can be a more cost-effective alternative to dedicated high-speed and lowspeed spindle machines.

Bryan Machine Service’s VRT spindles, originally designed for Haas Automation’s vertical machining centers, operate on compressed-air turbines with internal regulators that maintain the same speed in varying loads. In operation, a machine tool picks up the VRT spindle from the tool changer, like any other tool, and the coupler engages the air supply to the spindle.

VRT spindles use standard 11 ER collets, and when not in use, both sides of the autocoupler close to prevent coolant and debris from entering. A simple command engages the autocoupler and starts or stops the VRT when it is interfaced to a machine’s CNC. Plus, the VRT-NT model spindle does not require tools to make speed adjustments. Pushing a button and turning the spindle increases or decreases the speed.

The VRT spindle adapts to most existing CNC machines, including lathes. And for grinders, the coupler matches up to virtually any machine.

“If a shop has a very low-spindle-rpm machine, it can add the VRT variable highspeed spindle and quadruple the machine’s rpm capability,” Jeff Holtzapple of the Haas Factory Outlet in Fort Wayne, Indiana, said.

“A normal spindle will be limited to whatever that machine’s motor can generate. Being able to vary spindle speeds allows operators to optimize tool performance for whatever materials – soft or hard – they are cutting. Variable-rpm capability is the biggest difference between the VRT and other ‘speeder heads’,” he added.

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