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.

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This is not what the numbers show – for the hole at MMC the position tolerance is the biggest possible. When you have perpendicularity called out for a hole, your tolerance zone is a cylinder of size tolerance value that is perfectly perpendicular to your datum surface. Let’s assume, you have a positional callout tolerxnce the hole with MMC. The result is an LMC hole most precisely held locationally.

In my opinion, R F S condition is applicable in case of critical fitments fitments involving critical demands like wear control, leakage prevention, smoothness at precision motion etc. The question to ask yourself is: What do you mean when you give zero tolerance at mmc? You do not get any bonus tolerance if the size of your part becomes favorable. Like a -ve Bonus tolerance. They both control the perpendicularity of a hole in this example relative to a datum.

The statement is true only if location of the hole is controlled by position tolerance defined at MMC basis. 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. This is not correct. When that envelope departs from the LMC size, you have more material to work with and therefore can physically and by design permit more tolerance.


Any help would be appreciated. Click Here to join Eng-Tips and talk with other members! The bonus tolerance reduces the number of rejected parts by increasing the tolerance zone.

GD&T Symbols

I think they were occidentally swapped. For instance, you have a locating hole on a part, and the mating part has a holerance that goes into the hole and follows wherever the hole goes, obviously. The circle S is a now discontinued practice that just means that the tolerance or the datum is to be taken at regardless of feature size. Definition Bonus tolerance is an additional tolerance for a geometric control.

With an LMC specification, when the tooling core pin is largest, it needs to be located more precisely to ensure machining stock is available. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Out of which specified positional tolerance is 0. Thanks friends, Finally the LMC condition makes sense to me on the thin wall scenario.

Introduction to Bonus Tolerance

It simply means that you need to hold whatever geometric tolerance as specified. 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.

Bonus tolerance in LMC mousepotato, Quote: This means contolling location of the hole by position at LMC tolerance is not the way to go when you mostly care about assembly. There is no difference in what’s binus. Bonus tolerance in LMC Another example for a useage that benefits with the application of LMC is a precast hole intended for subsequent machining.


Bonus tolerance in LMC greenimi: What is Bonus Tolerance? Have a nice weekend everybody!! Defense manufacturing is all about project manufacturing and project accounting.

I hope this helps, good luck.

Tips on Calculating Bonus Tolerance

If the tooling core pin is smaller, the precision of location is relaxed. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. This section is an introduction to the bonus tolerance concept. Bonus tolerance in LMC The question to ask yourself is: The values were reversed somehow from the perpendicularity page.

Sure, stir the pot, and make the quick exit. The MMC modifier in the tolerance portion of the feature control frame denotes that a bonus tolerance is permissible.

In revisions to the standard earlier thanthe symbol to indicate that the tolerance was to be taken at RFS was an S enclosed in a circle. A functional gage is a gage that is built to a fixed dimension the virtual condition of a part feature; a part must fit into or onto the gage. I wonder, how do these symbols help parts fit together? Resources Digital Transformation may be defined in a number of different ways by analysts or enterprise software vendors.