What Is Resultant Condition?

If you are familiar with GD&T, you’ve probably heard of “virtual condition.” It is a number that represents a worst-case combination of a feature’s size along with its geometric tolerance. For instance, suppose we have the following example of a hole, with a size tolerance of 6 ± 0.2 mm:

                       

  
The worst case for assembly purposes would be the smallest hole that is also out of position: 5.8 – 0.3 = 5.5.  This virtual condition represents the “usable” area that the mating pin must fit within:

                     

  

Now, virtual condition is usually easy to identify with — ”think of assembling pins and holes together. But sometimes I may be concerned about the outside boundary, created by the largest hole that is also off center: 

                        

This outer boundary, called resultant condition, is calculated as: LMC + stated geo tol + any bonus, or: 6.2 + 0.3 + 0.4 = 6.9 mm. This represents the area where any portion of the hole’s edge may possibly fall.

This resultant condition is not of concern when dealing with assembly of holes and pins! But suppose we are simply punching a drainage hole in the bottom of a drip pan. Nothing will be assembling through this hole, but my concern now is that the hole’s edge not be too close to the edge of the sheet metal.

So be aware of both virtual and resultant condition formulas, for internal and external features.

6 Comments

  1. As per the above example on resultant and virtual condition.

    Maximum allowable Value for resultant condition is 6.9mm
    Virtual condition: 5.5mm
    Hole size dia 5.58-6.2

    • This is my question please…
      In continuation of my previous writing…..could you please let me know?

      How much deviation with respect to actual measure of the hole dimensionally an Inspector will allow? from the example on resultant/virtual condition.
      Question… maximum size of the hole inspector will measure
      Minimum size of the hole inspector will measure considering all possible resultant/virtual condition boundaries.

      Thanks

      • Kabir — there are two things to be measured: the hole size (diameter) and the hole position. It sounds like you are asking just about the size, so the deviation allowed is 5.800000 (minimum size) to 6.200000 (maximum size). I added the extra zeros to emphasize that these two numbers are the absolute limits; the accuracy of the instrument may vary.
        Then the position needs to be verified too. This can be done with a variable-readout instrument such as a CMM, or it could be done with a physical “functional gage” which would be a pin of 5.5 (the virtual condition). This gage would also need to have walls to simulate the datums, although those datums aren’t labeled on the given drawing.
        The resultant condition itself is usually not measured. But it can be determined if there is a need to preserve a certain wall thickness between the hole and the edges of the part.

  2. Sir, as I also visited few more links for the topic, there I read that resultant condition is variable parameter.
    Mathematical formula for the parameter :
    Resultant Condition = AME(Actual Mating Envelope)+ Geometric Tolerance + Bonus Tolerance
    Does AME changed​ to LMC

    • According to the current ASME standard, resultant condition is not a variable number. It is a constant number. This is different from the previous standard (1994), where the resultant condition was indeed a variable number.

      If the MMC modifier is used in a callout for a hole, then the resultant condition is the LMC size + the stated geometric tolerance + bonus tolerance for that size.

    • Hi Manish,
      The Bonus Tolerance is when your shaft is manufactured at LMC. it gets additional tolerance for positional shift.This is only applicable when modifier M is given in GTOL.
      This always vary based on real case. Bonus = MMC-Real dimension manufactured. When shaft manufactured at MMC bonus will be 0. So it just affects Resultant condition not virtual condition.
      For more details please visit:
      https://youtu.be/wLaXCJLQwCQ

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