GD&T Maximum Material condition
Mufaddal Rasheed 
A brief conceptual description of MMC or Maximum material condition in GD&T. What it means and what are its implication on tolerancing?
An important concept in GD&T is the material condition, specifically the maximum materia condition .
What is maximum material condition?
Let’s take a drawing of a part as shown which is a block and a centre hole.
Drawing with Size dimensions and tolerances :
There are three features of size dimensioned in the drawing.
When we consider maximum material condition, the values for each of these features of size would be.
The smallest hole (14.9) and largest widths (50.3 and 35.3)
MMC is nothing but the condition in which the part is heaviest with the “most material.”
An important concept connected to the MMC is Rule #1 .
Which states that there should be perfect form at MMC also called as Taylors principle.
When a pin is manufactured based on this drawing at its maximum size as measured .
When a pin is manufactured based on this drawing at its maximum size as measured .
The Taylors principle or Rule #1 says that the pin should be at its perfect form when manufactured at MMC
Rule #1 can be over ridden . Over riding Rule #1 would mean the Pin can have MMC size and still have form variations. There are certain ways to over ride rule #1 in GD&T
Learn more about how to Interpret GD&T callouts from this Free e-book on GD&T interpretations
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Geometric Dimensioning and Tolerancing: Basics
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Verification of manufactured GD&T drawing
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Categories: : GD & Tolerancing