Welcome to part three of the article on addendums. It covers a few tips on creating and implementing an addendum in your organization. How to implement an addendum is just as important as the creation process.
This section covers a few tips on creating an addendum. The tips are divided into three parts; useful information, tips for creation, and typical pitfalls to avoid.
The list below contains an example of useful information for creating an addendum. All of the items may not apply to your organization.
The list below contains an example of useful information for creating an addendum. All of the items may not apply to your organization.
The list below contains common addendum pitfall . All of the items may not apply to your organization.
This section covers a few tips on implementing an addendum. The tips include approvals/buy-in, distribution, and training. All of these tips may not apply to your organization.
Hopefully, some insights were gained with this brief look at addendums. As you may have noticed, I am an advocate of using addendums in large corporations. Developing an addendum renews the focus on the importance of drawings.
In a survey I conducted, I found that about 30% of the companies in the survey use addendums (or some sort of supplement to the Y14.5 standard), and about 15% mentioned that they felt an addendum would be useful in their company.
If you would like to see an example of an addendum, you can purchase a copy of the GM addendum by clicking the button below.
Does your company use an addendum? Do you have any suggestions for items that should be in a Y14.5 standard addendum? If so, add a comment below.
If you would like assistance in creating a corporate addendum, contact me at Alex@KrulikowskiConsulting.com
This part of the article on addendums to Y14.5 covers the five categories typically found in an addendum.
Throughout this article where a number appears between square brackets, e.g. [xx], it refers to the paragraph or figure that is being modified from the ASME Y14.5-2009 standard.
There are five categories of content commonly found in corporate addendums.
1. Allow the use of only one of several optional methods.
2. Change a default condition.
3. Clarify a concept, symbol, modifier, or definition for your companies' application.
4. Discourage/disallow the use of a concept, symbol, or modifier.
5. Document the use of a tolerancing practice that is not in the Y14.5 standard toolbox.
Examples of modifications in each content category are in the paragraphs below. Corporate addendums may include many or just a few modifications. This article contains a few examples of modifications that are common in addendums.
The format of an addendum varies in each company. The format shown here may not be optimal for your company.
The examples in this article are not arranged in the sequence of a typical addendum. The examples are grouped by category.
This content category is popular in addendums. Selecting an option when several practices are permitted in the Y14.5 standard is important because it helps to create consistent drawings and reduce confusion.
The list below contains a few examples of selecting an option from the Y14.5 standard.
In most cases default conditions are not revised in an addendum; they are addressed on the face of a drawing. What should be in an addendum is a list of which defaults should be overridden on your drawings and instructions on how to override them.
Changing a default can be beneficial because the default may not be the best for your company. For a list of common defaults in the Y14.5 standard, check out the blog article "Do you know which ASME Y14.5-2009 defaults apply to your drawings?") Click here to read the defaults article
If the default conditions are not the same for all types of parts in your company, the addendum should show what parts should have defaults overridden and how to denote the override condition.
The advantage of revising standard defaults on the face of a drawing is that the requirement or condition is visible to the drawing users.
Clarifying concepts from the Y14.5 standard is important because it reduces confusion by providing additional explanation of items that are not fully explained in the standard.
The list below contains a few examples where clarifying a concept from the Y14.5 standard could be in an addendum.
Each ASME standard contains a paragraph citing a list of additional standards it invokes and provides a method to determine which standards are partially invoked.
However, many companies have difficulty understanding exactly which standards, and which versions apply to their drawings.
Discouraging or disallowing the use of a symbol or concept is important because it reduces the number of tolerancing tools available for use on drawings. There are many tolerancing tools in the Y14.5 toolbox that are not needed for some types of parts. There are also tolerancing tools that are not used often.
There are subtle differences between some of the GD&T symbols. There are often discussions over which symbol is better for an application. The addendum focuses the discussions by disallowing or discouraging certain tolerancing tools leaving the tolerancing tools needed for defining your products.
Tolerancing tools can be disallowed for a variety of reasons. A few tolerance tools are overly restrictive for most applications or are not a good tool for your companies' applications. A few tolerancing tools that are only used in rare applications may be disallowed or discouraged to prevent their widespread use.
The list below contains a few examples of disallowing or discouraging a concept, symbol, or modifier.
Another area that I recommend companies to address is to discourage "extension of principle" on their drawings when a tolerance application is not in the Y14.5 standard or in their addendum. Even though the extended principle may make sense to the drawing creator, since its interpretation is not documented, it can be interpreted differently by drawing users.
Documenting the use of a symbol or concept that is not covered in the Y14.5 standard is important. It helps drawing users to have a consistent interpretation of the drawing requirements. If you add a new symbol or concept, it should be fully explained from a functional and inspection standpoint.
The list below contains a few examples of tolerancing tools that are not in the Y14.5 standard but may be needed. In this section, only example topics are listed, the entire addendum text and figures to fully describe these items are too lengthy for this article.
Adding new tolerancing tools in your addendum should be used sparingly. Adding new tolerancing tools can cause problems for CAD, analysis, and inspection software.
In part two, we looked at each of the five content categories of corporate addendums. Each corporate addendum is different based on their unique situation. Every addendum will not address all five of the above categories. An addendum may also include additional information not discussed in this article.
Part three of this article will be posted next week. In part three, you will learn a few tips on creating and implementing an addendum in your organization.
This article consists of three parts. The first part discusses whether using an addendum to the Y14.5 standard is a good practice for your company. The second part explains the five content categories typically found in an addendum. The third part provides tips on creating and implementing an addendum.
If you answered yes to any of the questions above, then you should consider creating an addendum to the Y14.5 standard.
I can read your mind. Some of you are wondering "Why do I need to go through the expense of creating and implementing an addendum when I am getting along just fine using the Y14.5 standard alone?
However, have you considered the following?
The Y14.5 standard is like a giant toolbox with tolerancing tools for all sorts of applications.
Imagine you were in a contest and won a giant toolbox filled with hundreds of different tools. The tools could handle almost any kind of plumbing, electrical, or mechanical repair job that came along. This toolbox has so many tools that knowing how or when to use all the tools would be difficult. The giant toolbox is good because you could use the tools that you are familiar with to do many jobs. It would also be bad because there would be tools that you were not familiar with and you might end up using them in the wrong places. The Y14.5 standard is similar to the giant toolbox.
The Y14.5 standard includes tolerancing tools for many applications. Having a standard that is like a giant toolbox is useful because it provides tolerancing tools that are needed for most applications in many companies. It also can be confusing because it contains tolerancing tools that are not useful in a particular company. This toolbox approach requires users to choose from several tolerancing tools to select the one that is best suited for their application
Which tolerancing tool is best for my application?
The Y14.5 standard contains many options and over a dozen defaults. In some cases, it provides multiple ways to communicate the same requirement. The Y14.5 standard also has a few tolerancing tools that need to be explained in more detail for some applications. There are also cases where there are tolerancing tools that are needed in a particular industry but are not covered in the Y14.5 standard.
An addendum can improve the use of the Y14.5 standard and guide users in creating drawings that are clear and consistent. An addendum is of particular importance for companies working Internationally due to the variations between ASME and ISO standards.
An addendum is a document that supplements the Y14.5 standard. It may also supplement other ASME standards as well.
In some companies, an addendum exists under other names like corporate standard, engineering standard, or another name. If your addendum documents a change to a default condition or adds a tolerancing tool, not in the standard, the addendum must be referenced on each drawing for interpretation. In this case, your addendum must also be accessible to all drawing users.
The word "addendum" is a bit misleading. An addendum does not only add new tools; it can also reduce or limit the tools based on corporate need. Most addendums result in a smaller more focused standard. In fact, many addendums contain very few new tools and mostly clarify existing tools, select options, or limit the tolerancing tools in the Y14.5 standard
Although this article, for the most part, discusses an addendum to the Y14.5 standard, however it is common for addendums to encompass additional standards.
An addendum can provide many internal benefits to a company as well.benefits when working with suppliers
Five benefits of using an addendum are shown below:
Part one of this article covered several aspects of corporate addendums. It defined what is an addendum. It also discussed why you should consider using an addendum and highlighted five benefits of using an addendum.
Part two of this article will explain and provide examples of the five major content categories of an addendum. Part two will be published next week.
Do you know which defaults from the ASME Y14.5 standard apply to your drawings? To correctly read a drawing, you must be able to recognize the defaults from Y14.5 and understand where they apply. Recognizing defaults is a bit tricky because they do not appear on a drawing. The Y14.5 defaults are described in the standard. If you are not aware of or cannot interpret the defaults, you are missing critical information about the requirements of the drawing. This article highlights ten of the common defaults from the Y14.5 standard.
A "default" is something that applies automatically. In Windows software, defaults can be the program that opens an image file or the fonts that are automatically used when you open your word processor. One nice thing about defaults is that you can change them.
In the Y14.5 standard, there is not a definition for defaults. I will start by defining the term "default condition" based on my interpretation of the standard and the way I use them in this article.
A default condition is a requirement, rule, specification, or method that has options allowed and one of the options automatically applies to a drawing. Default conditions can be overridden by specifying a different requirement, rule, specification, or method on the drawing.
There are two types of default conditions in Y14.5:
A default condition is often indicated in the Y14.5 standard by using the words "Unless Otherwise Specified..." (followed by or preceded by a description of the default.) However, in the Y14.5 standard, default conditions are not always stated using those words. Sometimes defaults are explained using other words or terms. In Y14.5 there are also some defaults that apply to a drawing when a specification is shown on the drawing that could be interpreted multiple ways, but one way applies automatically. These various methods used make some of the defaults in the standard difficult to recognize.
One common example of a default condition from Y14.5 is Rule #1 (perfect form at MMC from paragraph 2.7). Rule #1 is a requirement that applies automatically to feature of size dimensions. There are several ways to override Rule #1. Therefore, I consider Rule#1 a default condition. A default condition may have methods to override it listed in the standard or the methods to override a default may be open to the user to specify.
The bracket drawing is a simple part. Review the bracket drawing above and see how many default conditions you can find. You probably found several default conditions fairly quickly. But, without recognizing all of the Y14.5 defaults that impact this drawing, you will likely misinterpret the drawing. The misinterpretation could result in costly mistakes. I will highlight each of the Y14.5 defaults that apply to this drawing in the following paragraphs.
This section explains what I call the "coordinate system default". This default is from paragraph 1.4(p) in the Y14.5 standard. It states, "Where a coordinate system is shown in the drawing, it shall be right handed unless otherwise specified." A right-handed coordinate system is by far the most common on engineering drawings. Therefore, it is the default in Y14.5. For example, see the balloons labeled #1 in the bracket drawing. This default applies two places on the bracket drawing.
If you want to override right-hand coordinate system default and show a left-handed coordinate system, it must be designated in the drawing. The Y14.5 and Y14.41 standards do not show an example of a left-handed coordinate system.
Without the coordinate system default, coordinate systems on a drawing could be misinterpreted. This could result in parts being made that do not fit in the assembly and tooling could be built that may need to be scrapped.
This section explains what I call the "measurement temperature default". This default is from paragraph 1.4(l) in Y14.5. It states, "Unless otherwise specified, all dimensions and tolerances are applicable at 20° C(68°F)". An example of measurement temperature default does not appear on a drawing. On the bracket drawing, the balloon labeled #2 highlights the note that invokes the standard which in turn invokes the measurement temperature default.
You can override the measurement temperature default by adding a general note to the drawing stating the temperature to be used for measurement.
The measurement temperature default is important because parts expand or contract based on their temperature. To be able to compare measurements taken in different locations, the measurement must be taken at a consistent temperature. The temperature at which a measurement is taken can impact part acceptance or function.
This section explains what I call the "dimension/tolerance extent default". This default is from paragraph 1.4(n). It states, "Unless otherwise specified, all dimensions and tolerances apply for full depth, length, and width of the feature". On the bracket drawing, several examples of where this default applies are shown with the balloons labeled #3.
The dimension/tolerance extent default can be overridden with a note stating the extent of a dimension, using a between symbol, or a limited area designation.
Without dimension/tolerance extent default, confusion could exist on the extents of a dimension. This could cause disputes over part acceptance or functional problems.
This section explains what I call the "size envelope default." This default is from paragraph 2.7. It states, "Unless otherwise specified, the limits of size of a feature prescribe the extent within which variations of geometric form, as well as size are allowed". On the bracket drawing, there are five examples of where this default applies. They are shown with the balloons labeled #4.
The Y14.5 standard shows several ways the size envelope (Rule #1) default can be overridden. Rule #1 can be overridden by indicating...
The size envelope (Rule #1) default is important because it creates an envelope boundary that ensures parts will assemble. Without Rule #!, the form deviation of a feature of size could impact its overall size boundary and create an interference condition with the mating part.
This section explains what I call the "material condition default." This default is from paragraph 2.8. It states "Rule #2- RFS applies to the individual tolerance, and RMB applies, with respect to the individual datum feature reference, where no modifying symbol is specified". On the bracket drawing, there is one example where condition default applies; it is labeled with balloon #5.
The Y14.5 standard shows several ways the material condition (Rule #2) default can be overridden. They are to add an MMC or LMC modifier to the tolerance portion of a feature control frame or add an MMB or LMB modifier to the datum portion of a feature control frame. On the bracket drawing, there are several examples of where the material condition default is overridden.
The material condition default favors making the part tolerance more stringent and requires the designer to consciously widen the tolerance when the part function permits a looser tolerance. The material condition default condition raises part costs. Designers should be aware that a modifier should be specified wherever the more restrictive tolerance resulting from RFS or RMB is not required for the part function.
This section explains what I call the "thread P.D. default". This default is from paragraph 2.9. It states, "Each tolerance of orientation or position and datum reference specified for a screw thread applies to the axis of the thread derived from the pitch cylinder. Where an exception to this practice..." On the bracket drawing, there is one example where the thread pitch diameter default applies; it is labeled with balloon #6.
The Y14.5 standard explains that the the pitch diameter default can be overridden by adding notation such as "MAJOR DIA" or "MINOR DIA" beneath the feature control frame or datum feature symbol as applicable.
The thread pitch diameter default is important because it indicates which characteristic of a thread (major, minor, or pitch) a GD&T specification applies to. Without the thread pitch diameter default, the drawing would not be clear, and it could result in parts not assembling properly or other functional problems.
This section explains what I call the "datum feature simulator default". This default is from paragraph 4.5.2(c). It states that datum feature simulators have "basic location relative to other datum feature simulators for all the datum references in a feature control frame, unless..." On the bracket drawing, there are two examples of this default; they are labeled with balloon #7.
The Y14.5 standard explains that the datum feature simulator default can be overridden by indicating a translation modifier or by specifying a movable datum target symbol.
The datum feature simulator default is important because it indicates how the datum reference frame is to be simulated. Without this default, the datum simulation requirements would not be clear, and it could result in parts not assembling properly, differences in inspection results or functional problems.
This section explains what I call the "free state default". This default is explained in paragraphs 1.4(m) and 4.20. They state, "Unless otherwise specified, all tolerances apply in a free-state condition". On the bracket drawing, this default applies to all seventeen tolerance specifications on the drawing; they are labeled with balloon #8.
The Y14.5 standard explains that the free-state default can be overridden by a local or general restraint note.
The free state default is important because it indicates a part is to be measured without any external restraints. Without this default, whether a part may or may not be restrained for measurement would not be clear, and it could result in parts not assembling properly, differences in inspection results, or functional problems.
This section explains what I call the "profile tolerance zone default". This default is from paragraph 8.3. It states that "Uniform, bilateral, unequally disposed, or non-uniform tolerance zones can be applied to profile tolerances" The standard doesn't clearly state a default for a profile tolerance zone. However, according to the definition in this article, there is a default for profile tolerances zones. Several options exist in the standard for the type of tolerance zone with a profile tolerance. Since, by simply pointing to the true profile invokes one of the ways a profile tolerance zone can be located, it is considered the default condition. On the bracket drawing, there are two examples of profile tolerances with the bilateral tolerance zone default; they are labeled with balloon #9.
The Y14.5 standard explains that the profile tolerance zone default can be overridden by indicating an unequally disposed or non-uniform tolerance zone.
The profile tolerance zone default is important because it indicates how the tolerance zone is located relative to the true profile. Without this default, the requirements for a profile tolerance zone would not be clear, and it could result in differences in inspection results, parts not assembling properly or functional problems.
This section explains what I call the "simultaneous requirement default." This default is from paragraph 4.19. It states that "A simultaneous requirement applies to position and profile tolerances that are located by basic dimensions, related to common datum features referenced in the same order of precedence at the same boundary conditions". The standard doesn't clearly state that a simultaneous requirement is a default, but by the definition of default in this article, it is a default. Profile and position tolerances that meet the requirement stated in paragraph 4.19 could be a simultaneous requirement or a separate requirement. Since this option exists and no indication is required to invoke a simultaneous requirement, it is considered the default. On the bracket drawing, there are three examples of this default. They are labeled with balloon #10.
The Y14.5 standard explains that the simultaneous requirement default can be overridden by indicating "SEP REQT" adjacent to the geometric tolerances that meet the requirement in paragraph 4.19 in Y14.5.
The simultaneous requirement default is important because it indicates how position and profile tolerances that have the identical datum feature references are to be interpreted. Without this default, the requirements for profile and position tolerances would not be clear, and it could result in parts not assembling properly, differences in inspection results, or other functional problems.
How many default conditions did you find on the bracket drawing? Did you find all the defaults that are mentioned in this article?
This article focused on ten common default conditions from Y14.5. The drawing above shows that the ten defaults apply over 50 places on the simple bracket drawing. This highlights the importance of understanding the default conditions from Y14.5 and being able to identify where they apply on your drawings.
There are a few additional, less common, defaults in the standard that are not covered in this article. Did you find any additional examples that you would consider default conditions based on the definition in this article? If so, mention them in the comments section below.
Why depend on casual peer translations when you can have a professional translation of the entire Y14.5 -2009 standard? If you have German speaking colleagues working with drawings made to the Y14.5 Standard on Dimensioning and Tolerancing this is a valuable resource. Check out the link to the publishers website below to order a copy.
If your native language is German there are several benefits to using the translated version.
In conclusion, if the standard is written in a langauge you are familiar with, it will get used more and save time.
Date of issue: 2010-12First edition, 342 pages, A4, Broschiert
This book provides the translation of the ASME Y.14-5-2009 . This standard introduces uniform procedures for the specification and interpretation of dimensions, tolerances and associated requirements for application on technical drawings and related documents.
You can have instant access with an electronic version.