Maximum Material Condition (MMC) is the size of a feature of size for which the part contains the maximum amount of material. For an internal feature of size, the MMC size is the smallest allowable size.
![Maximum Material Condition Maximum Material Condition](/uploads/1/2/5/6/125623315/777193518.png)
For an external feature of size, the MMC size is the largest allowable size.When the MMC modifier is used, it indicates that the specified tolerance applies when the feature of size is at the MMC size. As the size of the feature of size departs from the MMC size, the tolerance is increased by the amount that the size departs from the MMC size. Least Material Condition (LMC) is the size of a feature of size for which the part contains the minimum amount of material. For an internal feature of size, the LMC size is the largest allowable size. For an external feature of size, the LMC size is the smallest allowable size.When the LMC modifier is used, it indicates that the specified tolerance applies when the feature of size is at the LMC size.
As the size of the feature of size departs from the LMC size, the tolerance is increased by the amount that the size departs from the LMC size. Consider the figure above. When gaging the pattern of four holes, the part is intended to be constrained at A, E, and F. Datum A is intended to take out the translation in the Z direction and the rotations about the X and Y axis.
Datum E is intended to take out the translations in the X and Y directions. Datum F is intended to take out only the rotation around the Z axis.If the part is gaged with two round pins at E and F, then the gage will treat these two holes equally. Both holes together will take out the translations in the X and Y and the rotation around the Z.The datum translation symbol allows a gage to be used that has pins for both holes E and F with the pin for hole F being free to translate. With F free to translate, hole E will take out the translations in the X and Y directions and hole F will take out only the rotation about the Z axis. Thus the part will be constrained exactly as intended by the feature control frame. The profile tolerance defaults to equally disposed about the true profile.
The goal of this blog post is to present the maximum material boundary (MMB) concept in GD&T applications. The maximum material boundary concept is simply the use of a maximum material condition on a datum feature, as shown in Figure 1 (the annotation B(M)). Sep 02, 2017 Maximum Material Condition (MMC) It refers to a feature of size.(The feature of size is nothing but the set of parallel surfaces associated with the dimension.) This is a condition where there exists a maximum amount of material within the given dimension tolerance zone. Maximum Material Condition is one side of the dimensional limits on a part.
Sometimes it may be desirable to have the tolerance zone unequally disposed about the true profile. In previous versions of the standard, this was done as indicated below. A basic dimension to a phantom line indicated the tolerance zone.
This method is still legal in the 2009 standard. However, in the 2009 standard, one can also use the U in a circle as indicated below. The number immediately following the unequally disposed symbol indicates the amount of tolerance outside the material.
The independency symbol overrides rule #1.Recall that rule #1 specifies a boundary that a Feature of Size is not allowed to violate. In the top row of the diagram below, the Feature of Size has a boundary 11 wide that it is not allowed to violate. If the part is made at 11, it is perfectly straight. If it is made between 10 and 11, it can be bowed as long as the part does not violate the 11 boundary.In the bottom row, the Independency symbol is used. The part must still be between 10 and 11 wide at any given point.
However, now the part can be 11 wide and still be bowed. As it is specified below, there is no limit to how much the part can be bowed. It is adviseable to include some other way of limiting the flatness error when overriding rule #1 with the independency symbol.
Maximum Material Condition (MMC)The maximum material condition is used when designing two mating parts.Taking a shaft designed to fit into a bore as an example, this specification ensures that the shaft actually fits into the bore under the, while also preventing excessively strict size tolerance from being applied in order to avoid cases where the shaft does not fit into the bore.What Is?To apply the maximum material requirement to a dimension, you write after the size tolerance in the. “M” stands for “maximum material condition' (MMC).
This symbol indicates the application of maximum material requirement. A Virtual sizeExpressing Maximum Material Condition Using a Dynamic Tolerance DiagramThe dynamic tolerance diagram is a tool that visually expresses the changes in the tolerance zone of size tolerance and geometric tolerance. By marking geometric tolerance on the vertical axis and on the horizontal axis, the variations in both size tolerance and geometric tolerance can be presented at the same time.
The application of the maximum material condition also clarifies the that occurs when the geometric tolerance increases. Drawing indication.