GD & T- FEATURE CONTROL FRAME

FEATURED CONTROL FRAME

·         It is symbolic representation of individual feature of the part/product that has been given in the engineering drawing in compartment form as given below.

·         Each compartmental symbols having its own meaning.

·         Each feature should have separate feature control frame.

 

LEADER ARROW

·         It is the direction given by arrow which denotes the requirement of applying GD & T on that position.

GD & T SYMBOL

·         It represents the operation controlled on given specific area or surface or axis. It has different symbols for different operation.

DIAMETER SYMBOL

·         It is given prefix with the tolerance if the axis control of diameter is required operation that means the given tolerance is for diametrical dimension.

TOLERANCE

·         It is the allowable deviation value for the given dimension and operation for that given feature is required.

·         It does not having plus or minus value that means the given value is the total tolerance of that feature.

MATERIAL CONDITION MODIFIER

·         It is the condition of material removal for maintaining the given tolerance limits. It may be maximum material condition (M) or least material condition (L).

DATUM CONDITION

·         It is the condition given by CAD engineer to manufacturer for maintaining the dimensions and its tolerances from that reference line. It may be primary, secondary and tertiary.

 

 

MATERIAL CONDITIONS

·         It is the availability of material into a part / component that could not exceed the tolerance limit.

MAXIMUM MATERIAL CONDITION (MMC)

HOLE

·         If the machining operation is Hole or any internal feature is given with MMC then operator needs to maintain smallest Inner dimensions in tolerance limits of the part.

PIN

·         If the machining operation is Pin or any external feature is given with MMC then operator should maintain its largest dimension in tolerance limit.

LEAST MATERIAL CONDITION (LMC)

HOLE

·         If the machining operation is Hole or any internal feature is given with LMC then operator needs to maintain largest Inner dimensions in tolerance limits of the part.

PIN

·         If the machining operation is Pin or any external feature is given with LMC then operator should maintain its smallest dimension in tolerance limit.