Position Tolerance on a Shaft expressed without a modifier

When expressed without an M or L modifier, the Position tolerance works on an RFS basis. It needs to be accounted for independently of the Size tolerance as shown in the animation.

Position Tolerance on a Hole expressed without a modifier

When expressed without an M or L modifier, the Position tolerance works on an RFS basis. It needs to be accounted for independently of the Size tolerance as shown in the animation.

Composite Frame Position Tolerance

A Composite Frame Position tolerance is used for patterns of Features. It has two segments.

• Pattern Locating Tolerance Zone Framework (PLTZF)

The PLTZF constrains the variation of location of the Pattern with respect to external Datums.

• Feature Relating Tolerance Zone Framework (FRTZF)

The FRTZF constrains the Feature to Feature location variation within the Pattern.

The segment that is used to model the variation is chosen based on how the gap is described. The animations show the cases for PLTZF and FRTZF variation.

Position and Orientation Tolerance on a Feature of Size

When Position as well as Orientation tolerance is applied to the same Feature of Size, the Orientation tolerance serves to refine the tolerance of Size. Once the Position variation is accounted for by DVA, a separate accounting of Orientation is not required to be done. The animation shows such a case.

Geometric Tolerance for a Shaft expressed with a M modifier

Where M or L modifiers are assigned to a Geometric Tolerance, the variation is caused by the following tolerances:

1. Pattern Locating Tolerance Zone Framework (PLTZF)
2. The Geometric Tolerance
3. Bonus Tolerance that accrues when the Feature size goes away from the Critical Limit of Size.

Bonus Tolerance is a useful concept that makes manufacturing processes less expensive. DVA needs to take correct cognizance of the 3 tolerances above to evaluate the Feature envelopes and consequently the gap. The animation shows a case of gap variation, when the Geometric tolerance is expressed with a M modifier.

Geometric Tolerance for a Hole expressed with a M modifier

Where M or L modifiers are assigned to a Geometric Tolerance, the variation is caused by the following tolerances:

1. The Tolerance of Size
2. The Geometric Tolerance
3. Bonus Tolerance that accrues when the Feature size goes away from the Critical Limit of Size.

Tolerance is a useful concept that makes manufacturing processes less expensive. DVA needs to take correct cognizance of the 3 tolerances above to evaluate the Feature envelopes and consequently the gap. The animation shows a case of gap variation, when the Geometric tolerance is expressed with a M modifier.

Geometric Tolerance for a Shaft expressed with a L modifier

Where M or L modifiers are assigned to a Geometric Tolerance, the variation is caused by the following tolerances:

1. The Tolerance of Size
2. The Geometric Tolerance
3. Bonus Tolerance that accrues when the Feature size goes away from the Critical Limit of Size.

Bonus Tolerance is a useful concept that makes manufacturing processes less expensive. DVA needs to take correct cognizance of the 3 tolerances above to evaluate the Feature envelopes and consequently the gap. The animation shows a case of gap variation, when the Geometric tolerance is expressed with a L modifier.

Geometric Tolerance for a Hole expressed with a L modifier

Where M or L modifiers are assigned to a Geometric Tolerance, the variation is caused by the following tolerances:

1. The Tolerance of Size
2. The Geometric Tolerance
3. Bonus Tolerance that accrues when the Feature size goes away from the Critical Limit of Size.

Bonus Tolerance is a useful concept that makes manufacturing processes less expensive. DVA needs to take correct cognizance of the 3 tolerances above to evaluate the Feature envelopes and consequently the gap. The animation shows a case of gap variation, when the Geometric tolerance is expressed with a L modifier.

Orientation Tolerance on a Surface

As shown in the animation, the Orientation tolerance of Parallelism on the surface refines the variation due to Size. The Size is defined across the Datum and the feature under measurement. Hence once Size variation is accounted for, a separate accounting of the Orientation tolerance is not required to be done

This principle applies to all other Orientation tolerances (Perpendicularity and Angularity) that may be applied in such a manner.

Flatness Tolerance on a Resting Face

Flatness is a Form tolerance. By default, Form tolerances refine size tolerances, and are consumed within the envelopes of size. Hence once the size tolerances are accounted for, a separate accounting of a Form tolerance is not required in DVA. The following 3 special cases of Form tolerances however, require a separate accounting of the tolerance towards DVA.

1. Flatness on a resting face
2. Flatness on a Feature of Size median plane expressed with a Modifier or expressed RFS.
3. Straightness on a Feature of Size median plane/ axis expressed with a Modifier or expressed RFS.

This case shows the impact of Flatness tolerance on a Resting face for two blocks. The impact of the Resting Face flatness can be seen on the gap variation.

Flatness Tolerance on a Feature of Size

Flatness is a Form tolerance. By default, Form tolerances refine size tolerances, and are consumed within the envelopes of size. Hence once the size tolerances are accounted for, a separate accounting of a Form tolerance is not required in DVA. The following 3 special cases of Form tolerances however require a separate accounting of the tolerance towards DVA.

1. Flatness on a resting face
2. Flatness on a Feature of Size median plane expressed with a Modifier or expressed RFS.
3. Straightness on a Feature of Size median plane/ axis expressed with a Modifier or expressed RFS.

Straightness Tolerance on a Feature of Size

Straightness is a Form tolerance. By default, Form tolerances refine size tolerances, and are consumed within the envelopes of size. Hence once the size tolerances are accounted for, a separate accounting of a Form tolerance is not required in DVA. Special cases of Form tolerances however require a separate accounting of the tolerance towards DVA.

Straightness on a Feature of Size median plane/ axis expressed with a Modifier or expressed RFS.

This case shows the impact of Straightness tolerance on a Feature of Size. It shows the largest and smallest envelopes that the Feature would describe.

Profile Tolerance − Equally Disposed

Profile tolerance is always expressed RFS and needs to be accounted for independently of other tolerances. By default the Profile variation is equally disposed around the Basic Profile.

The animation shows the impact of an equally disposed Profile Tolerance in DVA.

Profile Tolerance − Unequally Disposed

Profile tolerance is always expressed RFS and needs to be accounted for independently of other tolerances. The Profile tolerance expressed with a U modifier is unequally disposed around the Basic Profile.

The animation shows the impact of an unequally disposed Profile Tolerance in DVA.

Composite Frame Profile Tolerance

A Composite Frame Profile Tolerance has two segments. The Upper segment constrains the variation in the shape of the profile considering the Location and Orientation of the Profile with respect to external Datums.
The Lower segment constrains the variation in the shape of the Profile alone.
The segment that models the variation should be chosen based on the definition of the gap.

Composite Frame Profile Tolerance

A Composite Frame Profile Tolerance has two segments. The Upper segment constrains the variation in the shape of the profile considering the Location and Orientation of the Profile with respect to external Datums.
The Lower segment constrains the variation in the shape of the Profile alone.
The segment that models the variation should be chosen based on the definition of the gap.

Runout Tolerance

The Runout tolerance describes the difference in distribution of the feature surface in different orientations around the axis of rotation. Runout is always expressed RFS. Runout can occur due to axis shift, as well as due to variation in shape of the Feature under evaluation. The variation in shape is possible only to the extent the size envelope would allow. In DVA, the shape variation is therefore already accounted for once the size is taken into account. Towards DVA, the axis shift that causes Runout should be taken into account as shown in the animation.