Introduction to 3D Coordinate Measuring Machine CMM

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Introduction to 3-D Coordinate Measuring Machine
(CMM)

• Concurrent Engineering I
• MEM 380/800 561
• Week6-CMM
• Instructor Dr. Jack Zhou

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WHAT IS CMM?

• The MicroVal 454 Coordinate Measuring Machine is
  a high performance computerized Coordinate
  Measuring Machine
• The CMM machine can be used as a programmable
  inspection station with programmable flexible
  gauges for process control

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WHAT IS CMM?

• This system is combined with the Sharpe II
  Control System to provide users with the high
  speed Direct Computer Control capabilities
• One advantage of the CMM is that it allows
  unattended batch measurements, semi-automating
  the measurement process.

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WHAT IS CMM?

• The Controller servo board is capable of 0.001 mm
  resolution at speeds up to 175 mm/sec per axis.
• The machine is certified with an accuracy of
  0.00025 over 10.04 and a repeatability of
  0.00012

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3-Dimensional Coordinate Measuring Machine
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Feature Based Measurement

• Features
• point, 2-D line, circle, sphere, cylinder, cone,
  plane, 3-D line, center location, slot, bore,
  center line, bolt hole, offset
• Dimension
• 2-D distance, 3-D distance, Angle

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Feature Based Measurement

• Form
• straightness, flatness, roundness, cylindricity,
  sphericity
• Orientation
• parallelism, perpendicularity, concentricity,
  angularity
• Profile
• profile (scanning), surface (manual), output
  (graphics)

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Programming the CMM

• Step 1 Home the CMM
• establishes global coordinate system
• Step 2 Qualify the Tip
• compensates for tip diameter
• Step 3 Align the Part
• establishes a local coordinate system on the part
• Step 4 Measure the Part

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Step 1 Homing the CMM

• Select Initialize the CMM on the SOI screen
• Press the Machine Start button on the jog box
• Select DONE

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Step 2 Qualify the Tip

• Select Programmer Functions from the SOI screen
• Select Make a New Part
• Enter a name
• Select Done

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Step 2 Qualify the Tip

• Select Learn, then DONE
• Select Units
• Make sure metric is selected
• Select Measure Mode
• Make sure manual is selected

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Step 2 Qualify the Tip

• Select Qualification from the main menu
• Select Qualify
• Enter the reference sphere diameter and the
  offset, then select DONE

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Step 2 Qualify the Tip

• Place the reference sphere on the table
• Take at least five points on the sphere, one on
  the north pole, and four on the equator.
• When the points are taken, select DONE.

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Step 2 Qualify the Tip

• On the main menu, select Primary Control Option
• Select End Program

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Step 3 Align the Part

• Make a new part file and select Learn as was
  done to qualify the tip.
• Make sure units are metric and measure mode is
  manual
• Select Qualification from the main menu
• Select Load File

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Step 3 Align the part

• Load the file created in Step 2
• Select Recall Tip
• There should only be one tip called Tip1
• This is the specific tip data taken in Step 2
• Place the demo block onto the table

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Step 3 Align the Part

• Select Alignments from the main menu
• Select Line/Line Intersect
• Take at least three widely spaced points on the
  top surface of the block
• Select DONE when finished

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Step 3 Align the Part

• Take one point on the left front face of the
  block, select DONE
• Take another point on the right front face of the
  block, select DONE
• Take a point on the lower, left face of the
  block, towards the front, then select done
• Take a point on the lower, left face of the
  block, towards the back, then select done.

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Step 3 Align the Part

• This establishes the top plane of the block as
  the XY plane and the front and left edges as the
  X and Y axes.
• Select Primary Control Options from the main
  menu.
• Select Branch, which will insert a pause.
• Select Measure Mode, and choose DCC.

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Step 4 Measure the Part

• Select Features from the main menu
• Select the Circle icon

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Step 4 Measure the Part

• We will be measuring the circle shown below
• Take at least three points around the
  circumference of the circle

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Step 4 Align the Part

• The computer will calculate ideal approach
  vectors, then remeasure the part
• A report screen will appear, where nominal values
  and tolerances can be entered.
• Select the Primary Control Options
• Select Stop to save the program and exit

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Running a Part Program

• Select Load Part Program from the SOI
• Highlight the name of the file created in Step 4
• Select the Execute icon
• The program will prompt you to align the part,
  then it will measure the part.

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Then Go To the Metrology Laboratory to See Real
Demonstration

• Look at our Webpage for the lecture at
• http//cadpc3.mem.drexel.edu/cecourse
• for Week6-CMM