Geometric positional tolerance is given of.1 mm with modifier M. The modifier has specific meaning, It add a bonus tolerance. When shaft is at MMC there will b . GD&T bonus tolerance is an important concept for design engineer. This article will explain the Geometric Dimensioning and Tolerancing concept with an. When geometric tolerance is applied to a feature of size and it contain a MMC modifier in the tolerance portion of the feature control frame.

Author: Zolocage Fern
Country: Pacific Islands
Language: English (Spanish)
Genre: Education
Published (Last): 27 November 2009
Pages: 459
PDF File Size: 10.28 Mb
ePub File Size: 18.86 Mb
ISBN: 496-2-71351-816-1
Downloads: 26260
Price: Free* [*Free Regsitration Required]
Uploader: Jugore

If you specify the same tol at LMC, when the bigger hole becomes smaller towards MMC, the tolerance should get stricter. The internal feature hole is MMC at 9. This does not work well when you are considering a pattern of holes that function together such as a bolt hole pattern. Register now while it’s still free! Since the gage opening is constant, the thinner the washer becomes, the more straightness tolerance it could have and still pass through the gage.

So I don’t know how two assemblies are manufactured and fit together by the gdnt specs. We do plan on circling back and adding valuable content to the website in the future though. The statement is true only if location of the hole is controlled by position tolerance defined at MMC basis.

Bonus Tolerance

And before pmarc is pointing and question it and I realize it will confuse the OP I would say that: Then I should consider the diameter of the pin to be the dimension of the part envelope as maximum, is it correct?. This means contolling location of the hole by position at LMC tolerance is not the way to go when you mostly care about assembly.

You do not get any bonus tolerance if the size of your part becomes favorable. You already know that MMC for the hole will have the diameter of The values were reversed somehow from the perpendicularity page.


It all really depends on application. Close this window and log in. The bonus tolerance reduces the number of rejected parts by increasing the tolerance zone. That is actually a very important detail that I left out.

Result the mating part with pin will be off position more Any YouTube channels and videos will be of great help, because I can think only like a layman. Our True position box looks like this.

GD&T Symbols

Thanks in advance RE: The bigger the hole gets, the more position tolerance it will get. The Eng-Tips staff will check this out and take appropriate action.

How much bonus you will get? Bonus tolerance in LMC Another example for a useage that benefits with the application of LMC is a precast hole intended for subsequent machining.

When the actual mating size of the feature of size toleranc from MMC towards LMCan increase in the stated tolerance— equal to the amount of the departure — is permitted.

Bonus Tolerance Calculation – GD&T

Correct me if I’m wrong: So if you get some “bonus” from your employer that means you salary will be smaller stricter right?

Sure, this can check if two parts fit together and whether to throw them away if they don’t. Alex Kurlikovski Fundamentals book should be your best friend for the weekend. Let me be straight forward: But id you use LMC instead, if the hole gets bigger, you’ll have less positional bonus, and that’s the idea isn’t it?

Tips on Calculating Bonus Tolerance

Another way to think of it is that MMC is the condition that will result in the part being the heaviest, whether this is an internal or external feature. For locating purposes, I would recommend using LMC as it gives bonus tolerance for manufacturing, but you need to be careful not to end up with interference condition.


There are a few formulas associated but the main one is to calculate your virtual condition. RFS is used when the size of the feature has no direct impact on the location. All the holes that allow the 10 diameter gauge to enter should pass the quality checks. Bonus tolersnce in LMC “the tolerance should tolerancce stricter”??

I get annoyed when people just bury their heads in the sand. Bonus tolerance in LMC For locating toelrance, I would recommend using LMC as it gives bonus tolerance for manufacturing, but you need to be careful not to end up with interference condition.

If you really tolerahce into what you said here, you have described the exact same thing for two different scenarios. My original question If we have specified originally pos.

tolreance By joining you are opting in to receive e-mail. When the MMC modifier is used in the tolerance portion of the feature control frame, it means that the stated tolerance applies when the feature of size is at its maximum material condition. I wonder, how do these symbols help parts fit together?

If locating is important for a hole and a shaft, then the “play” between them can be arrested by an Lmc modifier. This section introduces bonus tolerance based on the MMC modifier. At MMC the maximum clearance available between the gauge and the hole is 0. Out of which specified positional tolerance is 0. I have some doubts regarding the perpendicularity at RFS.

Click Here to join Eng-Tips and talk with gx&t members!