Sanjay Gandhi

[Sanjay Gandhi]

Hi !

I am Graduate Mechanical Engineer, the new member of forum.

I have one question for all

When we have tolerance with MMC condition, we are getting Bonus for any deviation on feature dimension which is logical.

But my question is, can we apply the same rule of giving bonus for LMC condition too. ( CMM report gives bonus ) or we have to consider the penalty on tolerance from any deviation from LMC dimension ?

Have your opinion please,

Thanks and bye !

Sanjay

[Wes Cisco]

Sanjay,
Welcome to the forum. LMC works opposite of MMC. But the principal is the same. Most of the time if I see LMC on a print it is because the engineer wants to control wall thickness. If you are applying it to a hole then as the hole gets smaller, (more material), you gain bonus for location, as the hole gets larger, (less material), you loose bonus tolerance for location. With both the LMC and the MMC modifiers you can only gain as you deviate from the specified condition or else your feature is out of tolerance for size. HTH

[JoeRZ]

Sanjay,

When modifiers are included in the FCF it usually means to build the feature away from the callout ie. MMC for hole = min size, for shaft = max size, LMC for hole = max size, for shaft = min size.

Therefore, if you want to get the most of the callout... for MMC you need to build the hole towards the max size and for LMC build the shaft towards the min size. This is because the departure from size limits gets added to your geometric tolerance and allows more fit for part to function or mate.