I have issue with 840d sl  CNC that vertical axis get dropped down with 0.010 mm with emergency pressed . Is there any parameter available in GEN MD to apply delay . And what will be the cause .

I Have checked break relay found OK . Even PLC logic is OK .

Hi,

Is this measured on the motor encoder or a linear scale?.

Pee

Hi,

Servo inbuilt encoder measuring system used for feed back

 Does your machine have a holding brake in the vertical axis servomotor? If so,this is normal.

 These brakes will be in a "Clamped" state when there is no power to the axis motor. This locks the motor and holds the axis in position. Once power is sent to the motor, there is a signal also sent to power to the brake off which Unlocks or unclamps it. The axis is then held in position by the force of the servomotor. So, when you push emergency stop, power is cut to both the motor and the Unclamped brake.Without power, the motor will not hold the axis and it takes the brake a split second to "clamp" the motor in position. In that short period of time, the vertical axis drops due to gravity. This is most likely what you are experiencing .

Hi,

There is no reason for the motor to move after the brake is energised providing the brake is energised prior to the axis being disabled. Use of an e stop relay with a time delay allows for this.

If this is not the case then change the circuit so pulses remain enabled until the brake has been energised.

If the system already does this then it may be a counterbalance releasing or other mechanical quirk.

Pee

Pee El Sea

Hi,

There is no reason for the motor to move after the brake is energised providing the brake is energised prior to the axis being disabled. Use of an e stop relay with a time delay allows for this.

If this is not the case then change the circuit so pulses remain enabled until the brake has been energised.

If the system already does this then it may be a counterbalance releasing or other mechanical quirk.

Pee

 Hello Pee

Yes. You are correct about the brake energizing before the power to the motor is cut off if there is a time delay relay. But this time delay relay has to be provided by the machine builder. some of the turning machines I have worked on have no such relay and the weight of the the X-axis is not counterbalanced. Therefore the axis drops a bit when the emergency stop is pressed. The OP has not stated what machine he is refering too so we don't know for certain. If everything is wired through the Siemens control, Is there a parameter that changes an internal timer?