SEA Test Template and Instructions

Spindle Error Analysis Guide

A guide for measuring a machine tool with instructions on running the tests according to ISO and ANSI standards, followed by a template for a test report.

The report template can be modified and personalized as required for each unique situation.

Related Standards:

ANSI/ASME Standard B5.54-2005, “Methods for Performance Evaluation of CNC Machining Centers”
ANSI/ASME B5.57-2013 “Methods for Performance Evaluation of CNC Lathes and Turning Centers”
ANSI/ASME B89.3.4 2010, “Axes of Rotation, Methods for Specifying and Testing”
ISO230-3, “Determination of Thermal Effects”
ISO230-7, “Geometric Accuracy of Axes of Rotation “

Structural Motion (Spindle Off)

Related Standards Sections

ISO 230-7, 5.3
ASME B5.54, 7.5.2
ASME B5.57, 7.6.2

Conditions

Machine power on, spindle not rotating, drives, auxiliary, hydraulics off ( E-stop condition)
Machine power on, spindle not rotating, drives, auxiliary, hydraulics on (Feed-hold condition)

SEA Measurement Window(s)

Probe Meter

Oscilloscope and FFT optionally used for vibration analysis

Probes/Axes Used

X, X2, Y, Y2, Z

Purpose

Initial test to determine:

Robustness of setup (e.g. vibrations in probe nest due to weak interface plates, poor mounting)
Vibrations present in the machine’s structural loop due to external (e.g. floor vibrations) & internal sources (e.g. lubrication pumps, poor controller settings).
Possible presence of electrical error sources (e.g. EMC induced measurement noise).

Performing the test

Drives off (E-stop condition)

For each probe/channel,

Reset TIR of Probe Meter.
Wait 5 seconds
Record the TIR of the channel.

Drives, auxiliary, hydraulics on (feed-hold condition)

For each probe/channel,

Reset TIR of Probe Meter.
Wait 5 seconds
Record the TIR of the channel.

Oscilloscope and FFT displays can be used to assess vibration frequencies and amplitudes of repeating or intermittent vibrations.

Slow Speed Setup Test

Conditions

Spindle rotating less then 60RPM (driven or manually turned)

Probes/Axes Used

X, X2, Y, Y2, Z

SEA Measurement Windows

Probe Meter

Oscilloscope

Purpose

Measurement to check the setup while the machine’s spindle is rotating slowly.

Performing the test

Reset and observe the TIR indicator on the Probe Meter display for each channel as the spindle rotates.

Verify that that all channels remain in range during a full rotation

Verify masterball eccentricity

Typical eccentricity is 25-50µm or 10X expected spindle error maximum.

No eccentricity is required if using an encoder to trigger SEA measurements.

Environmental Temperature Variation Error (ETVE)

Related Standards Sections

ISO 230-3, 5
ASME B5.54, 6.2
ASME B5.57, 6.2.1

Conditions

Before Test: Machine must soak-out for a minimum of 12 hours at ambient temperature during which the spindle is not active.

During Test: Machine is in a “feed hold” condition. Surrounding environmental conditions during test must reflect typical conditions during machine operation.

Probes/Axes Used

X, X2, Y, Y2, Z

Temperature Sensors

SEA Measurement Window

Thermal

Recorded Values

Position shift in X, Y, Z axes

Tilt (X, Y)

Air temperature

Spindle nose temperature

Any other surface temperatures of interest

Purpose

The relative displacement of the tool with respect to the workpiece is measured and stored for this test. These measurements indicate the magnitude of spindle shift errors as a result of typical environmental conditions for the machine.

Performing the test

Mount probes and master ball

Place temperature sensor to measure air temperature

Place temperature sensor on nose of spindle

Place other temperature sensors as desired

After soak-out, set thermal sample time to 60 seconds with a total duration of 4 hours (minimum) to 24 hours (preferred).

Run test

Record sample results in table and insert screenshot of graph.

Thermal Drift

Related Standards Sections

ISO 230-3, 6
ASME B5.54, 7.6.2
ASME B5.57, 7.7.2

Conditions

Before Test: Machine must soak-out for a minimum of 12 hours at ambient temperature during which the spindle is not active.

During Test: Rotating spindle at 75% of maximum speed

Probes/Axes Used

X, X2, Y, Y2, Z

SEA Measurement Window

Thermal

Recorded Values

Position shift in X, Y, Z axes

Tilt (X, Y)

Air temperature

Spindle nose temperature

Purpose

The relative displacement of the tool with respect to the workpiece is measured and stored for this test. These measurements indicate the magnitude of spindle shift errors due to spindle generated heat during machine warm up and can help determine the minimum spindle warm up time required to meet specifications and deficiencies in the spindle cooling system.

Performing the test

Mount probes and master ball

Place temperature sensor to measure air temperature

Place temperature sensor on nose of spindle

Place other temperature sensors as desired

After soak-out, set thermal sample time to 5 seconds with a total duration of 60 minutes.

Run test

Record sample results in table and insert screenshot of graph

Initial Speed Range Test

Conditions

Rotating spindle stepped from low to maximum RPM (Caution: Do not exceed maximum RPM for the masterball).

Probes/Axes Used

X, Y, Z

SEA Measurement Windows

Rotating or Fixed Sensitive Radial

Axial

Oscilloscope (optional)

Analysis Configuration

Recorded Values

Radial

Synchronous Error

Asynchronous Error

TIR X

TIR Y

Axial

Fundamental

Residual Synchronous

Asynchronous Error

TIR

Purpose

Determine troublesome spindle speeds for further investigation during Full Analysis

Performing the test

Observe/Record Synchronous and Asynchronous error motion throughout spindle speed range.

After each change of speed, click the “Set Target RPM to Measured RPM” button in the Analysis Configuration window. This resets the DAQ for appropriate sample rates for that speed.

Look for Sweet Speeds (smallest error motion) and Sour Speeds (largest error motion). During Full Analysis, special attention may be paid to Sour Speeds to see if a cause/remedy can be found.

Full Analysis

For a full analysis, measurements are performed at a minimum of five equally spaced spindle speeds. Typical operating speeds should explicitly be used in this test. ANSI standards require that 10%, 50%, and 100% of full speed be included. For these tests, the measurements are stored separately (in ASCII code) as well and can be used for detailed analysis after measurements are completed.

Fixed Sensitive Radial and Axial (Lathes, Turning Centers, and Grinders)

Related Standards Sections

ISO 230-7, 5.5
ASME B5.57, 7.5.3

Conditions

Rotating spindle at selected speeds including common speeds for normal use.

Probes/Axes Used

X, Z

SEA Measurement Window

Fixed Sensitive Radial

Axial

Recorded Values at Each Speed

X (Radial) Error Motions: TIR, Sync, Async, Total

Z (Axial) Error Motions: Fundamental, Residual, Async, Total

Spindle Speed

Purpose

Measure error motions of spindle to determine machine capability and health

Performing the test

Set tests for 32 revolutions. Record all error motion values, for each selected speed, in report table.

Rotating Sensitive Radial and Axial (All Machine Tools)

Related Standards Sections

ISO 230-7, 5.4
ASME B5.54, 7.5.3
ASME B5.57, 7.6.4

Conditions

Rotating spindle at selected speeds including common speeds for normal use.

Probes/Axes Used

X, Y, Z

SEA Measurement Window

Rotating Sensitive Radial

Axial

Recorded Values at Each Speed

X, Y (Radial) Error Motions: TIR, Sync, Async, Total

Z (Axial) Error Motions: Fundamental, Residual, Async, Total

Spindle Speed

Purpose

Measure error motions of spindle to determine machine capability and health

Performing the test

Set tests for 32 revolutions. Record all error motion values, for each selected speed, in report table.

Tilt – Fixed Sensitive Direction

Related Standards Sections

ISO 230-7, 5.5.5
ASME B5.54, 7.5.3.2
ASME B5.57, 7.6.3.3

Conditions

Rotating spindle at selected speeds including common speeds for normal use.

Probes/Axes Used

X, X2 or Y, Y2

SEA Measurement Window

Tilt – Fixed Sensitive Direction

Recorded Values at Each Speed

Axis, Tilt Error Motions:Sync, Async, Total

Spindle Speed

Purpose

Measure tilt of spindle at various speeds and/or temperatures

Performing the test

Record all error motion values, for each selected speed, in report table.

Shift versus RPM

Related Standards Sections

ASME B89.3.4, 2.7.11

Conditions

Rotating spindle at selected speeds including common speeds for normal use.

Probes/Axes Used

X, X2, Y, Y2, and Z

SEA Measurement Window

Shift vs. RPM

Recorded Values at Each Speed

Shift in each axis and tilt

Spindle Speed

Purpose

Tests the position shift (displacement) of the spindle in X, Y, Z axes and X and Y tilt as the spindle speed is increased stepwise over a short period of time. As the spindle speed increases, mechanical loads within the spindle unit change (i.e. changing centrifugal forces, changing preloads) affecting the relative position of the spindle. This test can also reveal the actual status of the preload of the spindle bearings.

Performing the test

When test is complete, record position shift in each axis, at each speed for increase and decrease in RPM and insert screenshot of graph.

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