How does your spindle brake work?

[jnutter]

I bought a Hurco KMBI with an Ajax controller about a month and a half ago. I really like it except for how the spindle brake works. The way the P.O. wired this machine, the spindle brake only comes on when the E-stop is pressed.

My spindle brake is pneumatic, activated by two 110V 6 watt solenoids - one to open the disc brake caliper and one to close it. I'd like to make the spindle brake work one of two ways. 1) Turn it on using one of the Aux buttons or 2) have it engage automatically about 3 seconds after the spindle stops spinning.

Seems like I'm missing some documentation. I've read the install manual and it really doesn't cover this. The D sized shcematic shows a relay for a rotary brake that should be very capable of handling these solenoids (10A @ 250V) - but I'm not 100% sure that the relay was intended for the spindle brake and not a 4th axis rotary brake.

How does the spindle brake work on your Ajax/Centroid machine? Does anyone have one configured to come on automatically?

Does anybody know anything about settingup the controller to make it work the way I'd like?

[Al_The_Man]

How is the spindle motor controlled? If it is a variable speed, either AC or DC, there is usually a zero speed output relay, it is low current contact so if it has one you can use it to trigger a higher current relay that brings the brake on whenever the spindle see zero rpm.
Al.

[jnutter]

Mine has a 3ph motor controlled with an Automation Direct VFD.

I'll look at my schematics and see if there is anything like that.

[Al_The_Man]

Most VFD's have configurable outputs, you can set a spare one for zero speed.
Al.

[tsutt]

Al, Could a brake be used to help slow the spindle or stop it during a tap cycle. I'm running a vfd for spindle control. and the vfd braking kicks in at 60 hz. if i'm running 5000 rpm it take for ever for the spindle to stop. Todd

[MarcL]

Spindle brake control is a feature of the PLC programming, and therefore can vary from one control to another.

Typical recent practice has been to use the Aux3 key on the hand pendant to control the spindle brake "mode":
Aux3 On = Light On = Auto brake mode
Aux3 Off = Light Off = Brake off

In Auto brake mode, the spindle brake is released whenever the spindle is on, and applied whenever the spindle is off.

However, the PLC is not aware of any VFD deceleration time, so it will reapply the brake the instant you press Spin Stop or execute M5. If your VFD is programmed for ramped deceleration, it will end up fighting the brake. The simplest solution is to program the VFD for free coast on stops.

To program an Automation Direct GS2 or GS3 for free coast, set P1.00 = 1.

Again in typical recent practice, the actual spindle brake outputs are on OUT62 (to apply the brake) and OUT61 (to release the brake). These are 5VDC open-collector outputs on H4, the rightmost auxiliary output header.

To use these outputs to control your 110VAC solenoids, you will need to install either 5DVC relays (coil plus side to +5VDC pins of H4; coil minus side to respective output point; freewheel diode across relay coil to protect PLC from spikes) or use solid-state relays such as the IO-OAC-280 from www.power-io.com.

If you want to keep the active decel ramp in your VFD, and automatically apply the brake after the spindle actually stops, that can be done. It just requires a couple more wires between the VFD and the PLC, plus some custom PLC programming.

- Marc

[tsutt]

Thanks, Mark that's what i was looking for. Todd