Servo Bar 300 - How it Works and Troubleshooting Guide

How it Works

The Servo Bar 300 are used on Haas lathes made between January 1999 and April 2015. Bar feeders are fully integrated with the Haas CNC control and automatically load bar stock into the turning center for automated part production.

The bar feeder relies on motors and proximity sensors to load and feed bars into the turning center. A DC motor loads the bars onto the charging tray. A servo motor pushes the bars into the turning center. Proximity sensors measure the bar length make sure the bars are correctly loaded and fed into the turning center.

Servo Bar 300

  1. Home switch
  2. EOB (End of Bar) switch
  3. Load bar switch
  4. Load "Q" switch
  5. Ballscrew (trolley)
  6. Servo motor (trolley)
  7. DC motor (bar feeder)
  8. Charging tray
  9. Transfer tray
Symptom Possible Cause Corrective Action Section
Alarm 702 V AXIS POSITION ERROR The trolley hit an obstruction. Adjust the charging tray. 1
A bar is stuck. Clear bar path. 2
Alarm 712 V AXIS SERVO OVERLOAD The V Axis ballscrew is not lubricated. Check for ballscrew damage. 3
The servo motor does not operate correctly. Troubleshoot the servo motor. 4
Alarm 452 SERVO BAR MOTOR TIMEOUT The bar feeder lifter hit an obstruction. Remove obstructions from the lifter. 5
The DC motor brushes are worn. Measure resistance of the DC motor. 6
The proximity sensor does not operate correctly. (Load bar) Measure voltage to the proximity sensor. 7
There is no voltage to the DC motor. Measure voltage to the DC motor. 8
Alarm 423 SERVO BAR EOB SWITCH POSITION The proximity sensor does not operate correctly. (EOB switch) Measure voltage to the proximity sensor. 7
Alarm 175 GROUND FAULT DETECTED Cables are damaged or there is a contaminated electrical connection. Check for connector damage. 9
The brushes are contaminated or there is a carbon buildup. Check for contamination and remove dust. 10
Alarm 1015 CHECK SENSOR OR BAR The proximity sensor does not operate correctly (Load "Q"). Measure voltage to the proximity sensor. 7
Noisy The V Axis ballscrew is not lubricated. Check for ballscrew damage. 3
Inconsistent push lengths. Affected by previous push, pushrod timing delay, spindle liner size, chuck jaw size or grip strength. Troubleshoot the pusher. 11

Section 1

Symptom: Alarm 702 V AXIS POSITION ERROR

Possible Cause: The trolley hit an obstruction.

Corrective Action:

Make sure bar feeder charging tray is not too high. When the tray is too high, the bar feeder can attempt to load two bars. Refer to the bar feeder manual for more information.

Press RESET to clear the alarm.

Handle jog the V Axis away from the obstruction.

Section 2

Symptom: Alarm 702 V AXIS POSITION ERROR

Possible Cause: A bar is stuck.

Corrective Action:

  1. Squared-corner bar
  2. Transfer tray
  3. Chamfered-corner bar

The bar can get stuck when:

  • The bar is not chamfered: Bars must have a smooth path. Any sharp corner in the bar path must be removed. Sharp corners can cause problems when you load a bar. Collets and chucks must have lead-in corners chamfered. Leading ends of a bar must be chamfered. When you create liners or small use bar discs, use a generous lead-in chamfer.
  • The bar feeder is not aligned correctly: Refer to the bar feeder manual; it has specific instructions on how to correctly position the bar feeder and adjust the transfer tray.
  • The bar is caught on the chuck jaw: When you load a new bar, add a M19 code to your program to orient the chuck, and give the bar clearance to pass the chuck jaws.

Press RESET to clear the alarm.

Handle jog the V Axis away from the obstruction.

Section 3

Symptom: Alarm 712 V AXIS SERVO OVERLOAD. Noisy.

Possible Cause: The V Axis ballscrew is not lubricated.

Corrective Action:

Visually inspect the ballscrew. There should be a light coat of grease on the surface of the ballscrew.

note: Unlike the ballscrews for machine axes travel, the bar feeder ballscrew does not have an automatic lubrication system. It must be lubricated manually. Refer to the bar feeder operator's manual for more information.

If there is no grease, lubricate the ballscrew ballnut. If the symptom continues, go to Ballscrew - How it Works and Troubleshooting Guide to further troubleshoot the ballscrew.

Section 4

Symptom: Alarm 712 V AXIS SERVO OVERLOAD

Possible Cause: The servo motor does not operate correctly.

Corrective Action:

Make sure the motor connections are properly seated and the cables are not damaged.

Go to Servo Amplifier - How it Works and Troubleshooting Guide and Sigma 5 - Axis Servo Motor and Cables - How it Works and Troubleshooting Guide. Check for shorts to the motor.

Section 5

Symptom: Alarm 452 SERVO BAR MOTOR TIMEOUT

Possible Cause: The bar feeder lifter hit an obstruction.

Corrective Action:

The DC motor (bar load) motor moves the lifter. If there is a physical obstruction blocking the movement of the lifter, the motor has a slip clutch that will allow the motor to continue to move. If there is an obstruction, the proximity sensors will not be activated. Remove any obstruction from the path of the bar feeder lifter.

Section 6

Symptom: Alarm 452 SERVO BAR MOTOR TIMEOUT.

Possible Cause: The brushes are worn.

Corrective Action:

  1. Normal wear
  2. Excessive wear

Disconnect the motor from the connector. Measure the resistance from pin to pin. The resistance must be between 5-20 Ohms. Measure the resistance from one of the pins to the motor chassis.

The resistance must be greater than 100k Ohms. If the measurements are less, there is not a good contact between the brushes and the commutator. Clean any contamination between the brushes and the commutator. Brushes with excessive wear are faulty. New brushes are approximately 0.6" (1.5 mm) in length.

Section 7

Symptom: Alarm 452 SERVO BAR MOTOR TIMEOUT. Alarm 423 SERVO BAR EOB SWITCH POSITION. Alarm 1015 CHECK SENSOR OR BAR. Alarm 2092 BAR FEEDER OUT OF POSITION (Haas Bar Feeder only).

Possible Cause: The proximity sensor does not operate correctly.

Corrective Action:

Find the correct sensor to troubleshoot:

  1. Load bar (Alarm 452)
  2. Home switch (Alarm 469)
  3. EOB switch (Alarm 423)
  4. Load "Q" (Alarm 1015)

Test the sensor for correct operation: hold a key or other steel object in front of the sensor. If the sensor lights up, the sensor is not faulty. If the sensor does not light up, continue to further troubleshoot the proximity sensor.

Disconnect the cable [1] from the sensor. Use the marker [2] on the cable connector to measure the correct pins. Measure the voltage between the pins [3] and [4] on the cable connector. Make sure to use a multimeter with needle tipped probes.

The correct voltage is 12 VDC.

If voltage is correct, the sensor is at fault. Go to Proximity Sensor - How it Works and Troubleshooting Guide to further troubleshoot the proximity sensor.

If there is no voltage, go to I/O PCB - How it Works and Troubleshooting Guide (Classic Haas Control).

Section 8

Symptom: Alarm 452 SERVO BAR MOTOR TIMEOUT

Possible Cause: There is no voltage to the DC motor.

Corrective Action:

Run the DC motor: use G105 Q9 (Load Bar Stock) or G105 Q8 (Unload Bar Stock). Measure for DC voltage at the connector on the motor:

Adjust the multimeter range to 0.0 and set it for Min/Max. The power to the motor will only be on for one second before an alarm is generated and the power is shut off. The reading must be a minimum of 160 VDC, or show a signal change, when it is commanded to run. Some multimeters are not fast enough to read the voltage before the alarm occurs. It should still show a signal change or OL before the alarm is generated.

If there is no voltage and the signal does not change, go to I/O PCB - How it Works and Troubleshooting Guide (Classic Haas Control).

Section 9

Symptom: Alarm 175 GROUND FAULT DETECTED

Possible Cause: Cables are damaged or there is a contaminated electrical connection.

Corrective Action:

Perform a visual inspection of the motor cable and connectors. Make sure that the cable is in good condition and that the connectors are clean and secure.

Section 10

Symptom: Alarm 175 GROUND FAULT DETECTED

Possible Cause: The brushes are contaminated or there is a carbon buildup.

Corrective Action:

Power off the machine. Remove the brush caps from the DC motor (bar loader motor). Vacuum and clean the carbon dust from the motor and brushes. Check for wear or contamination in the brushes. New brushes are approximately 0.6" (1.5 mm) in length.

Section 11

Symptom: Inconsistent push lengths.

Possible Cause: Affected by previous push, pushrod timing delay, spindle liner size, chuck jaw size or grip strength.

Corrective Action:

The length of the push can be affected by the previous push: If the previous part over-shoots, the next push will be shorter. If the previous part slides back into the chuck, the next part will be long.

The pushrod moves away from the bar too soon: If the push rod moves away before the chuck can close, it can cause the bar to move back. This is more common with the collet chuck. Adjust Parameter 249 CHUCK CLAMP DELAY.

The spindle liner is too big, or there is no spindle liner: The chuck does not pull the bar against the rod when clamping or the chuck jaws are thinner. The thin jaws can cause the material to rock on the open jaws and fall forward or backwards. Material can also hit the back of the chuck and spring forward. Adjust the spindle liner to the correct size for the bar.

The bar moves after the pusher stops: Reduce the push speed: Adjust parameters 316, 317, and 323.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.

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