Roundness & the Limits of Size - GD&T

M

Mr. Friend

#1
Hi all, a very knowledgeable colleague of mine has made the claim that "when there is a diameter AND a roundness callout on a print, the average diameter and roundness must be within their respective tolerances in a free state" (see attached image).

He claims this is consistent with ANSI Y-14.5. I, however, disagree with this claim for the following reasons.

Section 2.7 of ASME Y14.5M-1994 deals with what the standard refers to as "Rule#1" whereby all form tolerancing takes place within the size limit boundaries. So circularity tolerancing would be a zone consisting of two concentric circles that cannot exceed the boundaries created by the size limits. The only exceptions would be if "notes" giving permission reside next to the feature or in the notes area of dwg. My understanding is that no element of the surface of a feature of size can violate the limits of size boundaries. The exceptions are stock, parts subject to free state variation in the unrestrained condition, or a straightness scenario which is described in section 6.4.1.1.2 when a feature control frame is "associated" with the size dimension (directly attached and not off to the side) of a straightness only. The Limits of size section directs the reader to this straightness section as the only form tolerancing allowed to violate the limits of size.


There is also a description of circularity in the standard that supports this, stating-" ....each circular element of the surface must be within the specified limits of size."(figure 6.8 section 6.4.3 -6.4.3.1).


I think that if the feature control frame has a note that states "AVG"(see section 6.8.3), or free state symbols, my colleague's claim is permissible. otherwise the claim violates the limits of size.

Is it possible that this claim is true? Is the claim not stating that if an average diameter measures at maximum size, and it contains an out-of-roundness condition, it still conforms as long as the out of roundness result does not exceed that listed in the roundness feature control frame? Am I reading this right?

-Mr. Friend
 

Attachments

Elsmar Forum Sponsor

Stijloor

Staff member
Super Moderator
#2
Rule 1 dictates that the boundary at MMC can not be exceeded. Form deviations are refinements WITHIN the limits of size.

The Standard also states when Rule 1 does not apply and when Rule 1 can be overridden.
 

Stijloor

Staff member
Super Moderator
#4
And what might be the exceptions?
To make a long story short, the best answer is in ASME Y14.5-2009. Pages 95-98. The text and graphics provided there make it very clear.

I have witnessed too many GD&T discussions here, where the posters do not provide adequate details such as the applicable GD&T standard and without correct references to the applicable paragraphs and drawings in the Standard.


.
 
Last edited:
M

Mr. Friend

#5
Thanks you for your response. 2009 actually shows a figure specifying circularity in a free state with average diameter in which it confirms what I had said concerning the requirement for disclaimers next to the diameter size or roundness feature control frame. So the word "AVG" would be required to reside next to the control information in order to consider average diameters.

Additionally, 2009 adds flatness as an additional exception (besides straightness, which was listed in 1994) but only if the "flatness tolerance is associated with the size dimension." (ASME Y14.5-2009 section 2.7.1). The Independency symbol is also introduced in this 2009 standard as well.
 

Stijloor

Staff member
Super Moderator
#6
Hi all, a very knowledgeable colleague of mine has made the claim that "when there is a diameter AND a roundness callout on a print, the average diameter and roundness must be within their respective tolerances in a free state" (see attached image).

He claims this is consistent with ANSI Y-14.5.
So, how are you going to heal your colleague from his misinterpretation(s)?

Another "good" one is concentricity. :popcorn:
 
M

Mr. Friend

#7
Well, actually the argument I posted at the top of this thread was copied from the email I had sent him him in which he responded by stating that his claim is in conformance with the standard. He didn't provide any textual evidence, however, so wanted to double check myself with some outside opinions.

I'm not too sure I want to engage in a second approach with my Quality Manager. And your suggestion is.....
 
Thread starter Similar threads Forum Replies Date
A Does Least-squares (LSQ) simulate perfect roundness? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
J Ball Bearing V-Blocks to ensure Lobing and Roundness are Minimal Manufacturing and Related Processes 1
C Roundness Tester Gage R and R Frustration - Tolerance range of 20 microns Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 13
M Runout Gage R&R - MSA on Roundness Tester - Minitab Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 9
H Uncertainty Calculation for Roundness - Talyrond 73 roundness instrument Measurement Uncertainty (MU) 3
S Laboratory Environmental Conditions Outside of limits ISO 17025 related Discussions 1
J How to Set Microbial Limits in Food Supplements Food Safety - ISO 22000, HACCP (21 CFR 120) 3
M Targets / limits for PPM/ Scrap Manufacturing and Related Processes 2
S Tolerance limits for micro balance General Measurement Device and Calibration Topics 1
samer Acceptable limits for Spills - Tracking Hydraulic Spills ISO 14001:2015 Specific Discussions 3
P Dropping ISO 9001 limits the scope of the ISO 13485 audit? ISO 13485:2016 - Medical Device Quality Management Systems 6
N Apply control limits to a non-normal distribution Statistical Analysis Tools, Techniques and SPC 13
D IEC 60601-1 - Performance limits for essential performance IEC 60601 - Medical Electrical Equipment Safety Standards Series 4
M IEC 60601 - Limits of agreement as Essential Performance IEC 60601 - Medical Electrical Equipment Safety Standards Series 3
M Calibration certificates avowing accuracy beyond the uncertainty limits? Measurement Uncertainty (MU) 7
L Gage R&R >10% - Decrease Machine Limits? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
G I-Chart and X bar Chart Control limits Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
N Converting ETO Residual Limits from PPM to mg ISO 13485:2016 - Medical Device Quality Management Systems 6
S GR&R using 10 Parts with different Specification Limits Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
P Setting Acceptance Quality Limits (AQL) for New Medical Devices ISO 13485:2016 - Medical Device Quality Management Systems 4
V Correlating Maximum 'Range' of Values for a given "RSD" (Control Limits) Statistical Analysis Tools, Techniques and SPC 3
H Control limits for varying subgroup sizes Statistical Analysis Tools, Techniques and SPC 1
G Procedure to define Signing Authority for Procurement Limits ISO 13485:2016 - Medical Device Quality Management Systems 2
T What to do if parameters are found to be Outside of Control Limits Document Control Systems, Procedures, Forms and Templates 5
S What is the Legal Limits of Fungi in Poultry Feed Food Safety - ISO 22000, HACCP (21 CFR 120) 2
E How to use the Standard Error and how to set the error limits? Reliability Analysis - Predictions, Testing and Standards 2
L How do I set a limits to cfu in an ISO class 7 Clean Room? ISO 13485:2016 - Medical Device Quality Management Systems 2
C Sewage Discharge Consents - Proving within Limits ISO 14001:2015 Specific Discussions 7
L Registrar Audit Scope and Limits ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 9
B Process Capability - Changing Limits to Improve Cpk or find Root Causes? Capability, Accuracy and Stability - Processes, Machines, etc. 6
K Historical Data to establish Control Limits Manufacturing and Related Processes 4
B Cleanroom Control Limits: Cumulative or individual? Statistical Analysis Tools, Techniques and SPC 11
S Product Bio-burden Limits and Sublethal Cycle Requirements ISO 13485:2016 - Medical Device Quality Management Systems 4
T Technical regulations that determine the acceptable limits of cigarettes General Measurement Device and Calibration Topics 4
D Calculating Lower and Upper 3 Sigma Control Limits Statistical Analysis Tools, Techniques and SPC 2
V Setting Specification Limits for UOD (Uniformity) for Live Bacteria or Spores Pharmaceuticals (21 CFR Part 210, 21 CFR Part 211 and related Regulations) 4
B How to set Cleanroom Alert and Action Limits as part of Microbiological Evaluation Quality Assurance and Compliance Software Tools and Solutions 8
K Advice on Calculating Control Chart Control Limits Statistical Analysis Tools, Techniques and SPC 13
B Non Acceptable % Tolerance Result - Decrease Sorting Limits Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
Q Setting Specification Limits Quality Tools, Improvement and Analysis 11
R ISO 14644-1 maximum particulate concentration limits concern Other ISO and International Standards and European Regulations 2
K Determining Control Limits from a desired Cpk Using Minitab Software 19
M Critical Limits for CCP in a food storage warehouse Food Safety - ISO 22000, HACCP (21 CFR 120) 4
T Calculation of Unified Thread Limits - Non-standard thread 1 ? 36 UNS-2A Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
P Critical Limits for Air Blower as CCP (Critical Control Point) Food Safety - ISO 22000, HACCP (21 CFR 120) 6
I Shewhart Constants vs Central Limit Theorem in calculating Control Limits Statistical Analysis Tools, Techniques and SPC 18
S Is a Stable Process (within Control Limits) required for Calculating Pp, Ppk? Capability, Accuracy and Stability - Processes, Machines, etc. 6
H Johnson Transformation in Minitab - How upper & lower spec limits are recalculated Using Minitab Software 1
D Are Four Sigma Control Limits based on Shewhart's work Statistical Analysis Tools, Techniques and SPC 3
H Specification Limits outside of Johnson Transformation Capability, Accuracy and Stability - Processes, Machines, etc. 15

Similar threads

Top Bottom