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VRT variable high-speed spindles, such as those developed by Bryan Machine Service for Haas, add multi-tasking flexibility and faster changeovers for machine tools.

When CNC automation replaced numerical control systems they effectively reduced the time required to changeover the machine to produce different components and they provided CNC operators with the flexibility and time to perform additional tasks.

The introduction of CNC machines changed the manufacturing industry – curves became as easy to cut as straight lines, complex 3D structures became relatively easy to produce, and the number of machining steps that required human actions reduced.

Now, machine tool automation is making another jump into multi-tasking.

Machine tool multi-tasking originated 25 years ago, but as of late has become popular with machine tool developers, and for good reason – such systems can show substantial improvements in yield, in some circumstances up to a 400 per cent increase in productivity.

Machine tool manufacturers are feeding this movement by continuing to expand their offerings of machine tools with multi-tasking functionality.

Although machine tool multi-tasking typically refers to processes that normally would require multiple machines – such as turning, milling, drilling, taping, boring and finishing a part – it can also delineate variable high-speed spindles that can perform multi-tasked functions within a CNC.

The latter is less well known because of its recent introduction into the CNC multi-tasking environment, but is rapidly gaining acceptance as a versatile combined high-speed/low-speed spindle alternative to the dedicated high-speed and low-speed traditional tools.

Many high-speed CNC machines do not have the torque for low-speed work and machines with lower spindle speeds cannot perform high-speed work.

When interfaced with a machine’s existing controls, these VRT variable high-speed, multi-tasked spindles can be used like any other tool in the machine’s tool changer, completely unattended.

There is no need to use a separate spindle for each speed to be run.

The spindle has a variable speed from 15,000 to 40,000rev/min.

This enables machines with lower spindle speeds to now also perform high-speed work and high-speed machines to perform low-speed work, using the same spindle.

The speed is externally adjustable and self-regulating.

Multi-tasking machines loaded with these spindles offer a great deal of production potential as they can often completely machine a part on its own.

These variable high-speed spindles reduce part costs because fewer spindles are needed.

Labour is reduced because multiple setups requiring additional handling are eliminated.

One tool can be applied to a wider range of applications, allowing for minimal inventory and machines themselves to be held by the manufacturer.

The higher degree of versatility enables one spindle to machine a various range of materials.

One manufacturer that is involved with variable high-speed spindle design is Bryan Machine Service (Bryan), which just last year introduced a line of multi-tasked high-speed spindles for CNC machining.

Originally designed for a Haas VMC, Bryan’s VRT spindles operate on a compressed air turbine with an internal regulator that works to maintain the same speed in varying loads.

The regulator is operator adjustable from the 15,000 to 40,000rev/min range.

When used in a CNC machine with its ACH125c auto coupler, it can outperform any tool in the CNC machine’s tool changer for unattended operation.

The machine tool will pick up the spindle out of the tool changer, like any other tool, then the coupler engages the air supply to it.

Along with the existing machine-controlled auto coupler, this spindle can be used like any other tool in the machine’s tool changer.

The spindle is adaptable to most existing CNC machines, including lathes.

For grinders, the coupler can be adapted to virtually any machine.

It uses standard 11ER collets.

When not in use, both sides of the auto coupler are closed to prevent coolant and debris from entering.

When interfaced to the CNC control, a simple command engages the auto coupler and starts or stops the VRT.

Bryan’s VRT-NT model does not require tools to make speed adjustments.

The pushing of a button and turning the spindle will increase or decrease the speed.

‘If there is a very low spindle rev/min on a machine, you can add the VRT variable high-speed spindle and quadruple the rpm capability of the machine,’ said Jeff Holtzapple, with the Haas Factory Outlet in Fort Wayne, Indiana.

‘A normal spindle will be limited to whatever that machine’s motor can generate.

‘By varying the speed of the spindle the operator can optimise the cutting of the tool.

‘If I have two tools made of different materials, one softer than the other, I may have to run the softer material at 15,000rev/min and the harder material at 40,000rev/min.

‘I have that capability of changing the rpm with this spindle,’ he added.

The Bryan spindle is located inside the existing machine spindle, uses air to generate increased rpm and uses the machine motion to make the cut.

It is very different from the typical spindle or other ‘speeder heads’ because it provides a variable-rpm capability.

It also allows the flexibility of interchangeability between the machine’s original spindle and the VRT variable spindle for tool changes as needed.

Bryan Machine Services

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