Machine Tool Metrology
Laboratory Overview

Spring 20
13

Pre Lab  General Overview (Will be done in class), 

LAB 1. Environmental and Dynamic Tests   Jan 23-24

LAB 2. Machine Control and Table Bending Check   Jan 30-31

LAB 3. Angular Error Measurements with Levels  Feb 6-7

LAB 4. Linear Displacement Measurements   Feb 13-14

LAB 5. Angular and Straightness Error Measurements  Feb 20-21

LAB 6. Notebook Quiz   &  Individual Laser Setups   Feb 25- Mar 15 (Sign up for times)

LAB 7. X-Y Laser Diagonals for Squareness Measurement   Mar 20-21

LAB 8. Measurement of Y Carriage Errors  Schedule Group Time (Mar 25- April 5)

LAB 9. API 6DOF Measurement Apr 10-11

LAB 10. Final Notebook  Quiz Apr 15-26  (Set up 1hour appointment)



Environmental and Dynamic Measurements
1.1 Contouring - ballbar
Lab Preparation (Read this):
Parametric Handbook #1 (PH1): Software Correction of a Vertical Spindle Machining Center (p1-10).[Opt. B5.54 Standard, Section 5.9 and all subsections.]
Lab Discussion :
   A. Operation of telescoping ball bars. Capacitive, LVDT, Laser, flexures.
   B. Discuss errors, backlash, scale errors, servo, straightness, vibration, squareness etc.
   C. CNC generation of a circular contour.
Lab Measurements:
   A. CNC Program.
   B. Take measurements at several feedrates.

1.2 Spindle analysis and Thermal discussion
Lab Preparation (Read this): [Opt. B5.54 Standard Sections 3.1, 3.2, 5.7(& subsections)]
Lab Discussion :
   A. Error motions, maybe show Lion Precision spindle error video.
   B. Thermal spindle growth, ambient effects, thermal structural loop.
   C. Discuss operation of the spindle error analyzer, nest, and wobble plate function, tilt measurement with double ball 5 gage gage nest. Discuss cap(acitance) gaging.
   D. Compliance.
Lab Measurements:
   A. Setup: adjusting cap gages and wobble plate.
   B. Measurement at various spindle speeds.
   C. Operation of Lion Precision Software.
   D. Do compliance illustration.

1.3  Heidenhein grid plate.


 2. Machine Control and Table Bending Check
Lab Preparation (Read this):
that you may be prepared
   Parametric Handbook #1 (PH1): Software Correction of a Vertical Spindle Machining Center (p10-12).
Lab Discussion : that you may broaden your knowledge
   A. Discuss Laboratory Notebooks
      i. info: machine, measurements, observations, procedures .
   B. Discuss machine mechanics and operation - ball screws, motors, scales, ways, controller (g-codes), jog, manual data input, program input (canned cycles), thermal effects, etc.
      i. Z-axis positive into spindle.
   C. Discuss Table bending, rigid body check
   D. Discuss use of levels to obtain relative angular measurement.
Lab Measurements: that you may develop experience
   A. Record machine general information (PH1 page 5) .
   B. Demonstration of machine operation basics : Referencing (home position, switches), jogging, manual g-codes, initial codes (metric/inch, rapid traverse, coordinate system (absolute/relative etc.).
   C. Measurement of Table bending (PH1 pages 10-12)
Lab Homework: that you may develop understanding
   A. Write CNC program [in ASCII (DOS) file] to move x in 50 mm increments and dwell for five seconds to do data acquisition -2 mm, 0, 50, 100... to 750 mm with 2 mm overshoot and reverse. The program should make 3 bidirectional runs with a feedrate of 1000 mm/min.
   B. Write CNC program as in A using variables and DO WHILE commands for arbitrary step, dwell, and number of bidirectional runs along a 3D linear path.
   C. Calculate Bending Coefficient for the table of  the VMC45.
   D. Review table bending data. Consider the design of the VMC 45 and give an explanation with illustration of why you think the table bends the way that it does.

3. Coordinate Systems and Measurements with Levels
Lab Preparation (Read this): PH1 (p13-27).
Lab Discussion :
   A. Coordinate systems, defining and alignment, relation.
   B. Machine errors, error directions, geometric, dynamic (contouring), spindle, thermal errors.
   C. Rigid Body assumptions, (table, non-moving axes).
   D. Level operation and measurement of Angles. Operation manual for levels is available.
   E. Angular error measurements with levels.
   Lab Measurements:
   A. Assignment of coordinate systems (Error, Tool etc.) and correction zone relative to machine coordinates.
   B. exx(x), Roll of x-axis measurement with levels.
   C. exy(y), exz(z) as time permits.
Lab Homework:
   A. Graph angular data sets as a function of scale reading.

4. Coordinate Systems and Linear Displacement Accuracy measurements
Lab Preparation (Read this):PH1 (p27-31)[Opt.B5.54 Standard Section 5.5].
Lab Discussion :
   A. Coordinate systems, transformations of point definition.
   B. Laser positioning measurement, simple theory.
   C. Origin to origin measurement and effect of position of optics (therefore must know positions of gages)
   D. Thermal expansion of scale, ball screw etc.
   E. Laser correction for humidity temperature and pressure.
Lab Measurements:
   A. Record, temperature, humidity, and pressure.
   B. Laser alignment techniques (all must align).
   C. Linear displacement accuracy measurement (x-axis).
   D. Minimum step (resolution) check.

Lab Homework:
   A. Correct linear displacement laser readings for T, P, H and the machine readings for thermal expansion due to deviation from 20o C.
   B. Graph all measured and corrected errors.
   C. Correcting  errors for optics offset from origin: Assume a 4 arcsec error at 400mm what would the additional error be? Explain and show math.

5. Angular and Straightness Error Measurements
Lab Preparation (Read this): PH1 (p 31-35) [Opt. B5.54 Standard Sections 5.8.2.2.5, 5.8.2.3. (all subsections)]
Lab Discussion :
   A. Angular measurement with lasers: theory.
   B. Straightness measurement with lasers: theory.
Lab Measurements:
   A. Angular measurement with laser (x-axis pitch and yaw).
   B. Straightness measurement with laser (along x, in y or z).
Lab Homework:
   A. Graph all measured and corrected errors.
   B. Be ready next week to align laser and do setups for linear, angular and straightness.

6. Notebook and Practical Quiz
   A. Setup and Alignment quiz. Each person will be required to separately align the laser and setup the optics as if you were going to do an actual measurement run. You will be required to do setups for measuring linear displacement accuracy, anglular errors, and straightness errors.
   B. First Notebook quiz: You will be required to use your notebook and most answers will be required to be referenced to your notebook.

7. Squareness measurements
Lab Preparation (Read this): PH1 (p46-52)[Opt. B5.54 Standard Section 5.8.4, 5.8.4.1(& subsections)].
Lab Discussion :
   A. Carpenters check for square.
   B. Laser Diagonal Measurements.
   C. Correction for optics positions, temperature, pressure, humidity (scale and laser).
   D. Laser mount on table.
Lab Measurements:
   A. XY diagonal measurement.
   B. YZ diagonal setup.
   C. XZ diagonal setup.
Lab Homework:
   A. Do squareness extraction from XY diagonals.
   B. Outline each step for doing A.
   C. Prepare for final lab exam (diagonal setup).

8. Measurement of the Y axis
Lab Group Assignment:

   A. Do necessary measurements to obtain dyy(y), dxy(y), dzy(y), exy(y), eyy(y), ezy(y)
   B. Do calculations to get above parameters. Discuss and show all work in journal. 

9.API 6 DOF Laser  Measurement

Lab Discussion
   The Automated Precison  Inc six-degree of freedom measurement system will be used to measure the X-carriage of the machine tool.
Lab Measurements: (as many as practical)
   A. Static measurements at positions measured before.
   B. Some dynamic measurments at different speeds
Lab Homework:
   A. Graphically compare API static measurements to those obtained with the HP laser after THP correction.  Graph data and differences
   B. Graphically compare the API dynamic measurements. Data and differences.
   

10. Final quiz
  
A. Final notebook quiz.
    B. Turn in Notebooks     

 



Construction began on this site 12-17-97
Last Update Jan 212