Service Spindle - Lathe - Troubleshooting Guide
Last updated: 02/14/2020

Spindle - Lathe - Troubleshooting Guide

Section 1: Introduction

The most common problems with a lathe spindle are vibration, noise and surface finish. 

Vibration is caused by runout. Look first at your workholding and your material. Ensure the chuck body or collet nose runs true; that your jaws are bored correctly; that your material isn’t running out. If you are bar feeding make sure the liner fits the material properly. If you still have a problem check runout of the hydraulic closer, the brake disc and all adapters.

If you haven’t fixed noise by addressing vibration above then the most likely cause is the drive belt. Make sure tension is correct; that the belt is in good condition; that shaft alignment is good and the belt isn’t forced against a pulley flange. 

If you have a surface finish problem that hasn’t been solved by the above then check the application: speeds, feeds, tool tip alignment, coolant flow, etc. also check machine alignments. 

For more lathe spindle symptoms please view the troubleshooting table below. For reference, the spindle drivetrain consists of the following:

  1. Chuck or Collet
  2. Drawtube
  3. Bearings
  4. Spindle Shaft
  5. Non-Contact Encoder Ring
  6. Sprocket
  7. Non-Contact Encoder Read-Head
  8. Adapter
  9. Hydraulic Actuator
  10. Coolant Collector
Symptom Possible Cause Corrective Action

Vibration

Alarm 966 Excessive Tool Imbalance

 Workpiece runout Indicate in workpiece runout depending diameter and spindle speed
Long bar stock or liner adapters with a poor fit Do not run bar stock past the hydraulic union stop. Only use tight fit liner adapters.
Spindle drivetrain misalignment Verify each component is within specified runouts - see Section 2
Spindle speed is running in a resonance frequency of the machine Speed up or slow down the spindle by 10% until vibration or surface finish improves
Spindle imbalance Run a vibration analyzer test.  Balance out high vibration using set screws in the union adapter - see Section 3
Motor vibration Run the motor without the belt to isolate motor vibration from spindle vibration
Damaged spindle bearings Run a vibration analyzer test to determine bearing health - See Section 6.  Test the spindle lubrication system - See Section 5 and the  Spindle Minimum Lubrication System Troubleshooting Guide
Encoder feedback Test the spindle to see if vibration goes away when you cut machine power and allow the spindle to coast to a stop
Spindle retaining ring alignment Sweep with a .001" shim between the spindle shaft nose and ring to check gap - adjust ring if needed
Bearing Noise Ball bearings and cage sound like they are skating around the races - caused by too little pre-load Run a vibration analyzer test to determine bearing health.  Inspect the spindle retaining ring step (that presses on the outer bearing race) for permanent deformation - see Section 6
High pitched whining noise - caused by too much pre-load Run a vibration anaylzer test to determine bearing health - see Section 6
Clicking noise - caused by a brinelling of the bearing which occurs when there is an impact to the spindle Run a vibration anaylzer test to determine bearing health - see Section 6
Belt Noise Tooth wear, tensile break, incorrect belt tension See Drive Belt Troubleshooting Guide and Section 4

Alarm 9918 Serial Encoder Fault

Alarm 9959 Serial Encoder Cable Fault

Alarm 4.103 Spindle Axis Servo Error too Large

 Encoder gap incorrect See Spindle Encoder Troubleshooting Guide and Section 7
Encoder ring damaged
Encoder cable damaged or loose
Alarm 174 Tool Load Exceeded Insert worn Inspect and replace insert if necessary
Tool load limit incorrect View the Advanced Tool Managment (ATM) tab to adjust user defined tool load limit
Aggressive feedrates Adjust your program for a more conservative feedrate

Section 2: Spindle Drivetrain Alignment

  • Check the runout at the following locations and adjust if necessary:
  • Radial runout of the hydraulic actuator rotary body on the steel strip [2] - NTE (not to exceed) 0.0005" TIR (total indicated runout)
  • Radial runout of the hydraulic actuator adapter on the inner diameter bore [1] - NTE  0.001"TIR 
  • Radial runout of the inner diameter of the drawtube [5]
    •  If more than 0.010" TIR this could indicate that the drawtube is not perpendicular to the bore of the hydraulic actuator piston
    • This causes excessive vibration and the drawtube would need to be re-installed
  • Measure the deflection on the side of the hydraulic actuator static body [3] or the coolant collector [4] while rotating the spindle. If more than .0015" TIR is measured, this will induce excessive vibration. You can attempt to loosen the screws that secure the actuator to the adaptor plate and lightly tap the rotary body of the actuator until you reduce the deflection runout on the static body. Use the vibration analyzer to see how this changed the vibration displacement and velocity plots.
  • Check the gap between the retaining ring (front spindle cap) and the spindle shaft nose using a 0.001" shim. To Align:
    • Break loose the retaining ring bolts
    • Tap the retaining ring to set the gap to 0.001"
    • Gradually tighten the bolts in a star pattern until they are torqued per the Haas Torque Chart
    • Verify the gap using a 0.001" shim

Section 3: Spindle Balancing

Lathe spindle balancing is applicable to re-boot ST machines. Use the Octavis Vibrational Analyzer program to view the displacement plot as you attempt to balance the spindle. If you do not have set screws to balance the spindle you can order kit 93-2867 .

There are balancing holes provided on the actuator adapter [1]. The goal is to make the displacement spike the lowest possible value at whichever speed the test is being run at.

  • If the Displacement spike decreases when a weight is added, then continue to increase the amount of weight inserted into the hole until the spike gets to the lowest possible value. Check that moving the weight or adding weight to the surrounding holes does not lower the spike as well.
  • If the Displacement spike increases, then remove weight and move to the next balancing hole on the union adapter until the Displacement spike reaches the lowest possible value. Experiment with small and large weights to get the best results.

Section 4: Belt Noise

Inspect the condition and tension of the spindle drive belts. A belt that is too tight or too loose will induce undesirable vibration. ST-30 NGC gearbox machines with prematurely worn belts will need the ST-30 Gearbox Non-Contact Encoder Upgrade Kit

Refer to the Drive Belts Troubleshooting Guide for more information.

Section 5: Lubrication System

Verify the spindle is getting adequate lubrication by completing a bottle test

  • Insufficient oil will cause premature bearing failure that will induce vibration
  • Excessive amount of oil will cause the bearings to overheat and prematurely fail

Refer to the Lubrication System Troubleshooting links below:

Section 6: Bearing Noise

Use the Octavis Vibration Analyzer to monitor bearing health.  Place the accelerometer on the side on the spindle head retaining ring or motor mount.

  • Run a vibration test throughout the machine's entire RPM range while taking note of the following:
    • Cage rattle - sounds like the ball bearings are skating on the races or the cage is rattling - [Velocity Plot 1]
    • High pitched squeel or screech caused by a ball flaw or damaged race- [Velocity Plot 2]
    • If you encounter an RPM where the machine makes noise, check the velocity plots for signs of bearing damage or cage rattle
    • Harmonic nodes where the machine displacement is amplified - these look like sudden increased in value spikes on the displacement plot.  Do these harmonic nodes correlate to the RPM where the machine is vibrating? If so - the machine is struggling with a resonant frequency.
  • If you note any signs of bearing damage, perform the following checks to verify the mechanical soundness of the spindle:
    • Check the machine history for any signs of a machine crash
    • Check the fore and aft movement of the spindle with an indicator on the spindle nose.  The movement should be less than 0.0005" if pushing by hand and the indicator should return to zero within 0.0001"
    • Check the axial and radial runout of the spindle nose.  Runout should be less than 0.0005" TIR
  • Corrective action includes:
    • Attempting to increase or decrease spindle speed in 10% intervals to reduce the affect of resonant frequencies
    • Balancing the spindle at the speed in which the owner most uses the spindle to reduce the displacement spike and reduce noise seen on the velocity plots
    • Verifying the spindle receives adequate oil (Section 5)
    • Check machine level and verify the machine is not too high up on the leveling feet
    • Check the step on the spindle retainer to see if it has permanent deformation.  The retainer must be removed to perform this check.
  • If nothing reduces vibration then the spindle may be at the end of its life and need to be replaced.  Contact Haas Service for approval if within warranty.

Section 7: Motor Encoder Feedback

The Haas spindle drive system is a Closed Loop System and requires continuous feedback from the encoder to precisely control the spindle speed via the motor. Inadequate encoder feedback could cause vibration and noise in the spindle drivetrain. Test the encoder feedback by turning the power to the machine off while running the spindle and let the spindle coast. If the vibration goes away when power is off, then troubleshoot the Encoder / Encoder belt / Wye-Delta Contactor / or Vector Drive.

  • If the machine is equipped with the non-contact spindle encoder, then check the read head alignment with the provided shim (incorrect read head alignment could cause unreliable feedback).

For Encoder troubleshooting information refer to the Spindle Encoder - Troubleshooting Guide.

For Vector drive troubleshooting information refer to the Vector Drive - Troubleshooting Guide.

For Belt troubleshooting information refer to the Drive Belts - Troubleshooting Guide.

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