ASME Y14.5 presentation by Alex Krulikowski May 2005
ASME Y14.5Proposal
on Feature of Size
ASME Y14.5 presentation by Alex Krulikowski May 2005
1. How to ensure minimum size is met on a feature of size where portions (or in some cases all) of the features are not opposed.
2. Clarify the definition of “size” in Y14.5.
3. Understand the definition of “size” from Y14.5.1
4. Using the size definition from Y14.5.1 to clarify what size means in Y14.5
5. Proposal to change Y14.5 to clarify: actual local size, opposed, size, and feature of size
Topics
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “feature of size” from Y14.5
1.3.17 Feature of Size. One cylindrical or spherical surface, or set of two opposed elements or opposed parallel surfaces, associated with a size dimension.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Dimensioning Concepts Applied to a Feature or a
Feature of SizeDimensioning Concept Applies to a Feature of Size Applies to a Feature
Flatness
Cylindricity
Datum Targets
Circularity
Profile of a Line
Tangent Plane
Position
Concentricity
Profile of a Surface
Bonus
Datum Shift
Viirtual Condition
MMC, LMC and RFS
Symmetry
Yes No
YesNo
Rule #1
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Opposite” from the Oxford English Dictionary
ASME Y14.5 presentation by Alex Krulikowski May 2005
Example of Fully Opposed Surfaces in Facing and Opposite
Directions
Facing _________from each other
A B C D
E F
Tab Tab
Slot
SurfacesSurfacesConsidered Facing
A & BB & CB & D
E & F
AwayTowardsSame Direction
Towards
OpposedOpposedSame
OpposedC & D Away Opposed
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Fully Opposed Line Elements Facing and Opposite
Directions
Facing _________from each otherSurfaces
SurfacesConsidered Facing
A & BB & CB & D
E & F
TowardsAwaySame Direction
Towards
OpposedOpposedSame
OpposedC & D Towards Opposed
A B C D
HE F G
G & H Towards Opposed
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed Features
4.
Surfaces A and B containgaps and interruptions
A
B
3.
Surfaces A and B are offset
A
B
1.
Surfaces A and B aredifferent lengths
A
B
Surfaces A and B aredifferent shapes
2.BA
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed Line Elements
A
Distance A containsoffset line elements
2.A
Distance A contains lineelements of different lengths
1.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Cylindrical Shapes with Truncated Ends
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Interrupted Features of Size
2X10.610.0
8.27.8
INTERRUPTED
2.62.0
0.2 M
INTERRUPTED
23.222.8
INTERRUPTED
0 M
0.2
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Partially Opposed
• There are at least 18 examples of partially opposed features of size in Y14.5.
• There are numerous cases of partially opposed features of size in industry.
• Partially opposed features of size cause problems when determining the LMC size in the non-opposed areas.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “feature of size” from Y14.5
1.3.17 Feature of Size. One cylindrical or spherical surface, or set of two opposed elements or opposed parallel surfaces, associated with a size dimension.
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
Definition of “Size” from Y14.5
Assumes Rule #1 is in effect
In Y14.5 the definition for size is limited.
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
Definition of “Size” from Y14.5
Problems with “Actual Local Size”
• The direction of measurement is not described, resulting in many answers possible for the value.
Actual local size
•Only works with “opposed points”
• It describes a “two-point” measurement
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
Definition of “Size” from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Size” from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Size” from Y14.5
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Size” from Y14.5
However, Y14.5 does not define how size is interpreted when Rule #1 is overridden
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
Y14.5 Invokes Y14.5.1
Y14.5 invokes Y14.5.1 which defines how size is interpreted both with and without Rule #1.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Size” from Y14.5.1
ASME Y14.5 presentation by Alex Krulikowski May 2005
Definition of “Size” from Y14.5.1
LMC
MMC
SPINE
ASME Y14.5 presentation by Alex Krulikowski May 2005A
Definition of “Size” from Y14.5.1
• A 0-dimensional spine is a point, and applies to spherical features.
• A 1-dimensional spine is a simple (non-intersecting curve in space, and applies to cylindrical features.
• A 2-dimensional spine is a simple (non-intersecting surface, and applies to parallel plane features.
Spine Types
ASME Y14.5 presentation by Alex Krulikowski May 2005A
Definition of “Size” from Y14.5.1
ASME Y14.5 presentation by Alex Krulikowski May 2005A
Definition of “Size” from Y14.5.1
ASME Y14.5 presentation by Alex Krulikowski May 2005A
When perfect form at MMC is required
Definition of “Size” from Y14.5.1
ASME Y14.5 presentation by Alex Krulikowski May 2005A
Definition of “Size” from Y14.5.1
When perfect form at MMC is required
ASME Y14.5 presentation by Alex Krulikowski May 2005
Size and Partially Opposed Features
• Actual local size requires fully opposed surfaces.
• Actual local size is defined as a two-point measurement. There is no direction for the measurement defined. Should actual local size be defined as a tolerance zone?
• Actual local size is only explained as a method for checking a minimum distance.
• How is a max size checked when Rule #1 is overridden as in figure 6-3?
In Y14.5 In Y14.5.1
• Does not require fully opposed features.
• Does not use the term actual local size. Uses two half space boundaries to define the size tolerance zone.
• Explanation for use with max or min size definition
• Works with or without Rule #1.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Size according to Y14.5
The 64.6 – 65.0 diameter is considered a feature of size. Using the Y14.5 definition of size, it is impossible to measure the actual local size of the diameter.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Now lets look at how the same size dimension would be interpreted using Y14.5.1
ASME Y14.5 presentation by Alex Krulikowski May 2005
Size according to Y14.5.1
The 64.6 – 65.0 diameter is considered a feature of size. Using the Y14.5.1 definition of size, the size tolerance zone of the 64.6-65.0 diameter is defined by two half space boundaries.
The boundaries are established by two balls: The MMC limit is defined by a ball equal to the MMC size. The LMC limit is defined by a ball equal to the LMC limit.
The balls are moved along appropriate spines to define the tolerance zone.
ASME Y14.5 presentation by Alex Krulikowski May 2005
Examples of Size Using Y14.5.1
10.610.0
Drawing Meaning
10.6 MMC boundary
MMC ball LMC ball
No difficulty measuring the portion of the feature that does not have opposed points
ASME Y14.5 presentation by Alex Krulikowski May 2005
Drawing Meaning
10.610.0
10.6 MMC boundary
MMC ball LMC ball
Examples of Size Using Y14.5.1
No difficulty measuring the portion of the feature that does not have opposed points
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
1.3.24 Size, Actual. The general term for the size of a feature. See ASME Y14.5.1 paragraphs 2.3.1 and 2.3.2 for an explanation of variations in size.
Text in Y14.5M-1994 Proposed Text
Text in Y14.5M-1994 Proposed Text
Delete paragraph 1.3.25 and replace all instances of Actual local size with Actual Size. (11 places in text and 4 places in figures)
Recommendations
ASME Y14.5 presentation by Alex Krulikowski May 2005
5-1
2.7 LIMITS OF SIZE
Unless otherwise specified (by specification of a straightness control applied to a size dimension, or a note as described in paragraph 2.7.2), the limits of size prescribe the extent within which variations of geometric form, as well as size are allowed. This control applies solely to individual features of size as defined in para. 1.3.17.
Text in Y14.5M-1994 Proposed Text
Recommendations
ASME Y14.5 presentation by Alex Krulikowski May 2005
Recommendations
• Show the MMC and LMC balls located along spines in several examples
• Add a paragraph and examples to explain “opposed”
• Add a paragraph and examples of features of size with partially opposed features.
ASME Y14.5 presentation by Alex Krulikowski May 2005
The end
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