Asme Y14 5m 2009
ASME Y14.5-2009 geometric dimensioning and tolerancing ( GD&T ) is a language of symbols used on mechanical drawings to efficiently, and accurately communicate geometry requirements for features on parts and assemblies. GD&T is, and has been, successfully used for many years in the automotive, aerospace, electronic and the commercial design and manufacturing industries. GD&T, both ASME Y14.5-2009 and Geometrical Product Specifications ISO series are the only recognized international drawing standards in use throughout the world. The ASME Y14.5-2009 and Geometrical Product Specifications ISO 1101(e)-2004 series are very similar and provide identical means to specifiy dimensional requirements. What are the Advantages?
In today's modern and technically advanced design, engineering and manufacturing world, effective communication is required to ensure the design and manufacture of successful products. Success oriented organizations, which require accurate and common lines of communications between engineering, design, manufacturing, and quality should consider (GD& T) as their mechanical drawing standard. Some distinct advantages of GD&T are as follows: GD&T facilitates an efficient means to communicate specific datums on a part.
A datum is just a fancy word for saying which specific feature on a part will be used as a reference (zero) for tolerance calculations, dimensional measurement, and most importantly, from where the feature(s) manufacturing should build from to ensure a consistent part. Without the use of a datum system (zero reference) on a part, it is not clear to manufacturing or quality where to manufacture or measure from. Additionally, the use of datums dramatically simplifies the design and specification of fixtures for use in manufacturing and quality verification steps. GD&T allows the use of round tolerance zones as opposed to square or rectangular tolerance zones as given by limit tolerancing methods for cylindrical (holes, shafts) features. In the mechanical drawing given in figure 1, there are four holes drilled thru the block, and each hole's location relative to each other and the edges are specified using a limit tolerance of a distance and +.005 and.005. This means the derived center of each of the holes must fall within a square tolerance zone.010 x.010 at some location, which as illustrated in figure 2.
Figure 1 Figure 2 In figure 2, there is a dimension attached to the top left and bottom right corners. This is the actual worst scenario for which the hole features may be manufactured (.014 or +.007 and.007). Therefore, a square tolerance zone defined at +.005 and.005 is actually +.007 and.007 worst case. Assuming the that this part must be interchangeable, or always fits in the target assembly when manufactured as specified above, then the +.007 and.007 is the real worst case scenario (not +.005.005).
The new ASME Y14.5-2009 standard on dimensioning and tolerancing reflects a culmination of effort extending over 15 years. It is a revision of the ASME Y14.5M-1994. Which statement best describes what the ASME-Y14.5M-2009 covers? A) Dimensioning and tolerancing standards for drafting and gaging of rigid mechanical parts. (This Foreword is not a part of ASME Y14.5M-1994.) Additions, modifications, and clarification.
In geometric dimensioning and tolerancing, cylindrical features may be located with round or cylindrical tolerance zones. Round tolerance zones offer several distinct advantages over square or rectangular tolerance zones. In figure 3, we have overlaid a round tolerance zone over our square tolerance zone for the part given in Figure 1. The shaded areas represent the increase in tolerance available by using round tolerance zone equivalent to the specified square tolerance zone in figure 1. As you can see, the hole may now be manufactured within the shaded areas where the square tolerance zone ends to the right, left, top, bottom at.007 off perfect center. This increase in available tolerance is equal to approximately 57%. A round tolerance zone is simply less expensive to manufacture, additionally GD&T allows for material modifiers, which allow for up to several hundred percent increase in tolerance, reducing manufacturing difficulty even more while maintaining interchangeability requirements.
Additionally, because the tolerance zones are round this allows the specification of similar features (round pin for a hole) on 'quick check' tools, such as go and no-go fixtures, where with square or rectangular tolerance zones, the verification tool requirements are not clear. Figure 3 Note: Applying one of the fourteen geometric characteristics defined within ASME Y14.5-2009 and ISO 1101(E)-2004 GD&T is not always required or the best approach for defining feature requirements on a mechanical drawing. The ASME standard does include requirements for limit tolerancing techniques. Regardless of industry or application requirements, ASME Y14.5-2009 and ISO 1101(E)-2004 GD&T is a great mechanical drawing standard, and is recognized throughout the world. Where's the Money, How do we Save? The above are only two examples of how GD&T improves communication, reduces manufacturing cost, and simplifies inspection. Actual savings realized by an organization migrating to GD&T on mechanical drawings will vary depending many factors, some examples are:.
Engineering and Manufacturing Team Size. Complexity of Parts. Mechanical Drawing Release Cycle Requirements. Production Requirements (Few or Many Parts). Organization Internal or External Manufacturing Facilities Case study: Internal machine shop contacts engineering and design to arrange meeting to discuss confusing mechanical drawing requirements. Cost impact as follows.
Action Cost Personnel Meeting 6 hours @ $70/hour = $420 Updating Mechanical Drawing 11 hours @ $70/hour = $770 Document Control $500 or $2000 Document Reproduction / Distribution $50 Total Impact $1740 or $3240 The case study above is a common miscommunication scenario where an organization has not established or trained for a mechanical drawing standard. Other common impacts are:. Part rejections due to difficult tolerance requirements (round vs. Square tolerance zone). Parts not interchangeable and being scraped. Inability to use best available industry quote due to vendor challenges with non-standard mechanical drawings.
Schedule impacts due to any of the above reasons Training all relevant personnel to the mechanical drawing industry standard (geometric dimensioning and tolerancing) will reduce confusion, increase available tolerance, and save time and money. Organization / industry (space / aerospace) studies, which I have participated within as a team member, have demonstrated a reduction in engineering and manufacturing change (change notices) at almost twelve percent following training, and full integration of geometric dimensioning and tolerancing per ASME Y14.5-2009. Who should be trained in Geometric Dimensioning and Tolerancing? Engineering, design, drafting, quality, dimensional inspection, and manufacturing should be trained to interpret, and as appropriate for their profession, apply GD&T. All of these professions utilize drawing interpretation and application knowledge to execute their responsibilities. Parts and procurement personnel should have some knowledge of GD&T to understand how to process a mechanical drawing for quote. Training personnel in the interpretation and application of GD&T will effectively reduce product design to market time, and production costs.
Kelly Bramble.
Example of geometric dimensioning and tolerancing Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating. It uses a symbolic language on and computer-generated three-dimensional solid models that explicitly describes nominal and its allowable variation. It tells the manufacturing staff and machines what degree of is needed on each controlled feature of the part.
GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features. Dimensioning specifications define the nominal, as-modeled or as-intended geometry. One example is a basic dimension.
Asme Y14 5m 2009
Tolerancing specifications define the allowable variation for the form and possibly the size of individual features, and the allowable variation in orientation and location between features. Two examples are and feature control frames using a (both shown above). There are several standards available worldwide that describe the symbols and define the rules used in GD&T. One such standard is (ASME) Y14.5-2009.
This article is based on that standard, but other standards, such as those from the (ISO), may vary slightly. The Y14.5 standard has the advantage of providing a fairly complete set of standards for GD&T in one document. The ISO standards, in comparison, typically only address a single topic at a time. There are separate standards that provide the details for each of the major symbols and topics below (e.g. Position, flatness, profile, etc.).
Contents. History The origin of GD&T has been credited to a man named Stanley Parker, who developed the concept of 'true position' in 1938. While very little is known about the life of Stanley Parker, it is recorded that he worked at the Royal Torpedo Factory in Alexandria, Scotland. Parker's work was used to increase production of naval weapons by new contractors.
Dimensioning and tolerancing philosophy According to the ASME Y14.5-2009 standard, the purpose of geometric dimensioning and tolerancing (GD&T) is to describe the engineering intent of parts and assemblies. The datum reference frame can describe how the part fits or functions. GD&T can more accurately define the dimensional requirements for a part, allowing over 50% more tolerance zone than coordinate (or linear) dimensioning in some cases. Proper application of GD&T will ensure that the part defined on the drawing has the desired form, fit (within limits) and function with the largest possible tolerances. GD&T can add quality and reduce cost at the same time through producibility. There are some fundamental rules that need to be applied (these can be found on page 7 of the 2009 edition of the standard):.
All dimensions must have a tolerance. Every feature on every manufactured part is subject to variation, therefore, the limits of allowable variation must be specified. Plus and minus tolerances may be applied directly to dimensions or applied from a general tolerance block or general note. For basic dimensions, geometric tolerances are indirectly applied in a related Feature Control Frame. The only exceptions are for dimensions marked as minimum, maximum, stock or reference.
Dimensions define the nominal geometry and allowable variation. Measurement and scaling of the drawing is not allowed except in certain cases. Engineering drawings define the requirements of finished (complete) parts. Every dimension and tolerance required to define the finished part shall be shown on the drawing. If additional dimensions would be helpful, but are not required, they may be marked as reference. Dimensions should be applied to features and arranged in such a way as to represent the function of the features. Additionally, dimensions should not be subject to more than one interpretation.
Descriptions of manufacturing methods should be avoided. The geometry should be described without explicitly defining the method of manufacture. If certain sizes are required during manufacturing but are not required in the final geometry (due to shrinkage or other causes) they should be marked as non-mandatory. All dimensioning and tolerancing should be arranged for maximum readability and should be applied to visible lines in true profiles.
When geometry is normally controlled by gage sizes or by code (e.g. Stock materials), the dimension(s) shall be included with the gage or code number in parentheses following or below the dimension. Angles of 90° are assumed when lines (including center lines) are shown at right angles, but no angular dimension is explicitly shown.
(This also applies to other orthogonal angles of 0°, 180°, 270°, etc.). Dimensions and tolerances are valid at 20 °C / 101.3 kPa unless stated otherwise.
Unless explicitly stated, all dimensions and tolerances are only valid when the item is in a free state. Dimensions and tolerances apply to the length, width, and depth of a feature including form variation. Dimensions and tolerances only apply at the level of the drawing where they are specified. It is not mandatory that they apply at other drawing levels, unless the specifications are repeated on the higher level drawing(s). (Note: The rules above are not the exact rules stated in the ASME Y14.5-2009 standard.) Symbols Tolerances: Type of tolerances used with symbols in feature control frames can be 1) equal bilateral 2) unequal bilateral 3) unilateral 4) no particular distribution (a 'floating' zone) Tolerances for the profile symbols are equal bilateral unless otherwise specified, and for the position symbol tolerances are always equal bilateral.
For example, the position of a hole has a tolerance of.020 inches. This means the hole can move +/-.010 inches, which is an equal bilateral tolerance. It does not mean the hole can move +.015/.005 inches, which is an unequal bilateral tolerance. Unequal bilateral and unilateral tolerances for profile are specified by adding further information to clearly show this is what is required. Geometric tolerancing reference chart Per ASME Y14.5 M-1982 Type of control Geometric characteristics Symbol Character Can be applied to a surface?
Can be applied to a feature of size? Can affect virtual condition? Datum reference used? Can use modifier? Can use modifier? Can be affected by a bonus tolerance?
Can be affected by a shift tolerance? Retrieved 2017-07-28. Retrieved 2017-07-28. Dimensioning and Tolerancing, ASME y14.5-2009.
NY: American Society of Mechanical Engineers. Further reading. McCale, Michael R. Journal of Research of the National Institute of Standards and Technology. 104 (4): 349–400. Henzold, Georg (2006). Geometrical Dimensioning and Tolerancing for Design, Manufacturing and Inspection (2nd ed.).
Oxford, UK: Elsevier. Srinivasan, Vijay (2008). 'Standardizing the specification, verification, and exchange of product geometry: Research, status and trends'. Computer-Aided Design. 40 (7): 738–49.
Drake, Jr., Paul J. Dimensioning and Tolerancing Handbook. New York: McGraw-Hill. Neumann, Scott; Neumann, Al (2009). GeoTol Pro: A Practical Guide to Geometric Tolerancing per ASME Y14.5-2009. Dearborn, MI: Society of Manufacturing Engineers. Bramble, Kelly L.
Geometric Boundaries II, Practical Guide to Interpretation and Application ASME Y14.5-2009. Engineers Edge. Wilson, Bruce A. Design Dimensioning and Tolerancing. US: Goodheart-Wilcox. External links Wikimedia Commons has media related to.
Tests implementations of GD&T in CAD software.