What are MMC LMC and RFS?
What are MMC LMC and RFS?
Material Modifiers provide one of three callouts that describe whether a feature contains the maximum or minimum amount of material when fabricated, thus affecting the overall tolerance of the feature. MMC – Maximum Material Condition. LMC – Least Material Condition. RFS – Regardless of Feature of Size.
What is material condition?
The aspects of a period of time that influence a person’s lived experience such as: the modes of production; the quality and quantity of materials available and accessible to individuals; and the morals, customs and laws that delineate the proper use and trade of said materials.
What is maximum material condition example?
In GD, maximum material condition (MMC) refers to a feature-of-size that contains the greatest amount of material, yet remains within its tolerance zone. Some examples of MMC include: Largest pin diameter. Smallest hole size.
What is maximum material condition in GD?
Maximum Material Condition (MMC) and Least Material Condition (LMC): Simple Definitions. MMC is the condition of a feature which contains the maximum amount of material, that is, the smallest hole or largest pin, within the stated limits of size.
What is MMC modifier?
Maximum Material Condition Modifier (MMC): The circled M. This provides a feature with additional geometric tolerances as the feature’s size departs from its maximum material conition. This provides a feature with additional geometric tolerances as the feature’s size departs from its least material conition.
When should MMC be used?
Reason for Use: If you want to ensure that two parts never interfere, or limit the amount of interference between the parts when they are at their worst tolerances, MMC can be called out. Take a shaft that must go through a hole with clearance between the two.
Why maximum material condition is used?
The goal of a maximum material condition callout is to ensure that when the part is in its worst tolerances, the Perpendicularity and size of the hole/pin will always assemble together. This means that if you make a pin smaller, you make more bonus tolerance for yourself.
What is RFS GD?
Definition: Regardless of Feature Size (RFS) is the default condition of all geometric tolerances by rule #2 of GD and requires no callout. Regardless of feature size simply means that whatever GD callout you make, is controlled independently of the size dimension of the part.
How is MMC condition calculated?
For an feature of size specified at MMC, Resultant Condition = LMC + Geometric Tolerance allowed. This is a single tolerance and size event.
What does the CF modifier indicate?
“CF” stands for “continuous feature.” This requirement is indicated when features need to be geometrically treated as a single feature.
What is the difference between RFS and maximum material condition?
RFS is used when the size feature does not affect the specified tolerance. Maximum Material Condition (MMC): MMC can be used to constrain the tolerance on given dimension/dimensions.
What is the use of RFS in RFS?
RFS is commonly used when the size tolerance and geometric tolerance need to be more tightly controlled, such as the case with press fits and threads. There is no bonus tolerance at RFS. Can Virtual Condition exist at RFS?
What is the difference between RFS and regardless of feature size?
Regardless of Feature Size (RFS) requires no callout on a drawing because it is the default condition for geometric tolerances in GD according to Rule #2 in the ASME Y14.5 1994 and 2009 standard. Regardless of Feature Size means that the geometric callout (such as perpendicularity) is controlled independently of the size dimension of the part.
What is the difference between the RFS and MMC virtual conditions?
Notice that the Virtual Condition at MMC for the internal feature results in the same calculation as the Inner Boundary at RFS. The same is true for the Virtual condition of an external feature compared to the Outer Boundary at RFS. The difference in boundary calculations is only in terminology.
