Post on 04-Jan-2016
description
Geometric Dimensioning and Tolerancing
Unit 4 – Position Verification
EML 2023Computer Aided Design
Coordinate Measuring Machine (CMM)
• Typical ‘bridge’ CMM is composed of 3 axes.
• A touch probe indicates contact with a body.
• Typical precision measured in microns or micrometers (10-6 m)
EML 2023Computer Aided Design
EML 2023Computer Aided Design
CMM
EML 2023Computer Aided Design
EML 2023Computer Aided Design
EML 2023Computer Aided Design
Position Tolerance Verification
• This unit covers some simple verification techniques for position tolerancing.
2.500
1.500
Position TolerancingVerification
2.503 Actual
.003
.004
X² + Y² = Z² - Pythagorean Theorem
X² + Y² = Z
X² + Y² = Diameter Tol Zone2
Actual Manufactured Part
Let us check this part to see if the hole location is within tolerance.
2.500.750.758
1.500
CBA.010
.750±.005
A
B
C
1.504Actual
.005
2X .005 = Ø.010 Tol Zone
Size of hole is producedat .750 (MMC).
M
3.6
4.7/4.8
2.500
1.500
Position TolerancingVerification
2.503 Actual
.003
.004
Actual Manufactured Part
2.500.750.758
1.500
CBA.010
.750±.005
A
B
C
1.504Actual
.005
2X .005 = Ø.010 Tol Zone
M
Since the hole is produced at MMC (.750), it is allowed .010 position tolerance. The actual calculated position of the hole falls within the .010 zone.
3.6
3.62.500
1.500
Position TolerancingVerification
2.506 Actual
.006
.005
Actual Manufactured Part
2.500.750.758
1.500
CBA.010
.750±.005
A
B
C
1.505Actual
Size of hole is producedat .755.
M
Let us try another example, this time the hole is produced at .755.Is the location good or bad?
Let us check this part to see if the hole location is within tolerance.
4.7/4.8
2.500
1.500
Position TolerancingVerification
2.506 Actual
.006
.005
2.500.750.758
1.500
CBA.010
.750±.005
A
B
C
1.505Actual
.00782X .0078 = Ø.0156 Tol Zone
M
If the hole is produced at .755, it is allowed a position tolerance of .015. The calculations show the hole is produced within a .0156 zone, so the hole location is out by .0006.
The above part may be repaired by opening the size of the hole by .0006.
3.6
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371
MMC =Smallest Hole
MMC = Smallest Hole
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376
Actual Size of Hole
Actual Size of Hole
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010
.005 Position
Plus
.005 Departure from MMC
.010
Position + Departure from MMC = .010
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010
X Deviation
-.004
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002
Y Deviation
Y Deviation
4.5
4.7
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002
From Chart
.0089
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002
From Chart
.0089 X
4.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.3714.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .3794.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .379 .0134.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .379 .013 +.0044.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .379 .013 +.004 +.0054.5
4.7
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .379 .013 +.004 +.005 .01284.5
Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
.371 .376 .010 -.004 +.002 .0089 X
.371 .379 .013 +.004 +.005 .0128 X4.5
POSITION
Hole Verification at MMC
4.3
Workshop Exercise
4.6 - Inch
4.14
Workshop Exercise
4.6 - Inch
4.14