137070172 Unigraphics NX8 Modeling

[NX8 HELP] MODELING 1

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A. What are you looking for in Modeling?

How do I?

Create a datum coordinate system

Create a sketch

Extrude a solid body

Revolve and unite a section



Create a conic edge blend

Create surfaces

Create expressions

Edit features

Create an assembly

Create product and manufacturing information

(PMI)

Create a drawing

Validate the design

Manage files with Teamcenter

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Part modeling overview

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B. Part modeling overview

The modeling process you follow to design a part is the same whether you design stand-alone parts or

design parts within an assembly. The decisions you make at each step depend on your design goals.

These are some of the main steps in the process of designing parts in NX.

Start with a new file.

1. Create an empty file for your part model. 2. Add the empty file to the assembly as a

new component to design the part within

an assembly context.

Design parts within an assembly to create

proper fit and alignment to other parts, and to

avoid unintentional interferences.



Select the History mode.

Define the History mode at the top of the Part

Navigator

Use history mode to model parts when

parameter changes are expected. This is

the traditional mode for highly

engineered parts.

Use History-free mode when you do not

know what types of changes to expect,

for example for a conceptual design.

This mode is often used with

Synchronous Modeling commands.

Define your modeling strategy.

Decide if your final part will be a solid body or

a sheet body. This will impact your modeling

strategy of which features to build first

Solid bodies are preferred for most

models because they provide an

unambiguous definition of the volume

and mass.

Sheet bodies are sometimes used for

manufacturing or simulation. They may

also be used as trimming tools for solid

body models

Create datums.

Create datum coordinate systems and datum

planes to position modeling features.

These datums form the beginning of a chain of

associativity for the features you add next.



Create features.

Create features according to your modeling

strategy.

1. Start with design features such as extrude, revolve, or sweep to define

basic shapes. These features typically

use sketches to define sections.

2. Continue adding other features to design the model.

3. Finish with detailed features such as edge blends, chamfers, and draft to add

the final details.

C. Features created by sweeping

Features created by sweeping are characterized by moving geometry through space. The geometry being

swept is referred to as section geometry.

Swept features can be classified into two types:

Vector driven (extruded, revolved)

Guide/spine/path driven

You can sweep either a single section or a set of section geometry.



You can also create swept features with offsets.

You can create a solid body or sheet body from the section geometry, based on the body type

setting at creation.

Solid

Sheet

The commands that create features by sweeping include:

Extrude

Revolve

Styled Sweep

Swept

Sweep along Guide

Variational Sweep

Tube

Associativity

Features created by sweeping are fully associated with the section or guide geometry.

If you delete associated parent curves, such as a sketch that has been extruded into a solid body,

you are notified that other features are affected and the solid body is also deleted.

If you select a solid face or datum plane to trim or limit a swept feature, the resulting feature is

associated to the face or datum plane.



For example, if you select a face to limit the end of an extrude feature, the extrude feature will

update when you change the shape or location of the face.

If you select a line, edge, or datum axis to define the direction of extruded feature or the axis of a

revolved feature, the resulting feature is associated with the selected reference.

Closed swept features

If the guides form a closed loop, the first section can be selected again as the last section to create a

closed body.

1. First section 2. Second section 3. Last section 4. Closed guide

1. Section geometry

You can use the Type Filter to control what type of geometry can be selected for the section:

Curves

Curve features

Sketches

Edges

Faces

Section Segments

You can use the Curve Rule to quickly define the section with fewer number of selections:

Single Curve

Connected Curves

Tangent Curves

Face Edges

Sheet Edges

Feature Curves

Region Boundary Curves

Infer Curves

After you select the objects for the section, the ends are highlighted by an asterisk if the section is not

completely closed.



2. Section geometry and intersections

When defining sections for sweeping, you can select contiguous or non-contiguous geometry.

If you select a set of non-contiguous geometry that extends beyond

intersection points, you will get an self-intersection error message.

Stop at Intersection used in conjunction with the Curve Rule

setting lets you signal which portions of the section curves to use.

Non-contiguous curves that do not extend to the intersection point can

only be used if the gaps are within the distance tolerances specified for

the feature.

The Extrude and Revolve commands will produce multiple sheet bodies

if the gaps are greater than the distance tolerance.

How section curve connections are interpolated depends on where section geometry is selected.

If there is any ambiguity in the selected curves, asterisks alert you to selection decision areas. Your

subsequent selections determine the section.

Example 1



Example 2

3. Swept feature error scenarios

Avoid creating a situation where vertices or edges of section geometry create a body of zero

thickness.

You will be alerted to possible error situations by display of

an asterisk where problem occurs.

If you continue, the operation will be completed, ignoring

problem areas and you will get an error message alerting

you of a self intersecting section.

When using swept features for boolean operations such as a Subtract or Unite, be sure the feature

actually comes in contact with the model.

Cylindrical extrusion and revolve share mass; Unite operation

successful.

Cylindrical extrusion and revolve share mass; Subtract operation

successful.



Cylindrical extrusion and revolve do not share mass; any Boolean

operation will be unsuccessful.

'Tool Solid Completely Outside Target Solid' error message is

issued.

Specifying closed and opened curves together as one section, or curves intersecting each other,

will yield error messages:

o 'Gaps in strings or multiple loops'.

o 'Selected objects will result in a self intersecting section'.

If the selected objects are not contiguous and the gaps are not within the distance tolerance, you

may receive a 'The section contains multiple loops' message.

Avoid situations where a swept feature would intersect itself if created. This usually happens with

revolve features whose swept axis is within the boundaries of the section geometry.

You will get an 'Unable to Trim' message if a potential swept feature cannot be intersected with

the start or end limiting geometry.

D. Feature modeling

Feature modeling is the process of adding features to your model to create the design. Features that you

add are listed in the Part Navigator.

You typically start a design with datum features, such as datum coordinate systems and datum planes.

These can be used to position other features, such as sketches.

Working in History mode, the software maintains associativity between features as you create them. For

example, when you create a sketch and revolve it, the software maintains associativity from the sketch to

the revolve feature.

To see the parent and child relationships of a feature, select the feature in the Part Navigator.



In this example, feature (2), a revolve feature, is selected in the Part Navigator. The magenta color

indicates that feature (0), a datum coordinate system, and feature (1), a sketch, are both parent features of

the revolve feature. Feature (3), an edge blend, is highlighted in blue to indicate that it is a child of the

revolve feature.

If you edit the sketch, the revolve feature updates because it is a child of the sketch. When the revolve

feature updates, the edge blend also updates, and so on.

1. Feature Modeling

The term "Feature " is used generally in NX to describe a class of objects that have defining parents. A

feature's parents enable it to recall the inputs and the operation that were used in its creation. Features

include all solids, bodies, primitives and certain wireframe objects.

Features can be described by the following characteristics:

The inputs of a feature are its "parents" and the resulting feature object is the "child," which is

Associative or "associated with" its parents.

Parents can be geometric objects or numerical variables (known as Expressions). In the case of

numerical variables, the numbers are known as "parameters" of the child object, and the child is

said to be "parametric."

If any object is modified, its associated children are updated (regenerated) to reflect the change.

The combination of parents and the creation operation is sometimes known as the "history" of an

object.

The parent-child analogy can be extended further within NX, and it is reasonable to speak of

ancestors, descendents, siblings, orphans, reparenting and so on.

Other Common Terms Used in Feature Modeling

Listed below are the most common terms used in Feature Modeling.

Body A class of objects containing solids and sheets.



Solid Body A collection of faces and edges that enclose a volume.

Sheet Body A collection of one or more faces that do not enclose a volume.

Face A region on the outside of a body enclosed by edges.

Creating Solid Bodies

You can create solid bodies by:

Sweeping sketch and non-sketch geometry to create associative features (see Swept Features).

Sweeping sketch and non-sketch geometry lets you create a solid body with complex geometry.

This method also gives you total control over the editing of that body. Editing is done by changing

the swept creation parameters or by changing the sketch. Editing the sketch causes the swept

feature to update to match the sketch.

Creating primitives for the basic building blocks, then adding more specific features, such as holes

and slots to provide further detail.

Creating a solid body using primitives results in a simple geometry solid body. Making changes to

primitives is more difficult, because primitives cannot always be parametrically edited. You can

use primitives when you do not need to be concerned with editing the model. Generally, however,

it is to your advantage to create the model from a sketch.

Modeling space

All bodies must be within a 1000 x 1000 x 1000 meter cube, centered about the origin of the

absolute coordinate system.

o Tolerances can have an impact on how bodies get created in modeling space.

Example If the spline is being used as a guide curve and is long and nearly straight and the

default distance tolerance (0.01") is used, the spline is approximated using a large

arc whose radius could be outside the maximum part size limit of 1000 x 1000 x

1000 meters.

You can avoid this problem by increasing the distance tolerance.

The smallest linear value that can be applied to a body is 0.00001 millimeters or 0.00000039

inches.

o Any linear value less than or equal to 0.00001 millimeters is considered to be zero for

operations on bodies.



Feature Parameter Customer Defaults

Use File Utilities Customer Defaults to specify defaults for Modeling feature parameters and dialogs. For further information, see the Customer Defaults Help.

Basic Terminology

Feature Refers to all solids, bodies, and primitives.

Body A collection of faces and edges. This includes both solid bodies and sheet bodies.

Solid body A collection of faces and edges that "close up" to enclose a volume.

Sheet A body with zero thickness, made up of a collection of faces and edges that do not "close

up" to enclose a volume.

Face A region on the outside of a body, separated from other faces by strings of edges.

Section

curves

Curves that you sweep to create a body.

Guide

curves

Curves used to help define the path for the sweep operation.

Common Concepts

The following options and topics appear throughout Feature Modeling options.

Object

Selection

Throughout all Feature options you are required to select objects.

Defining

Points

All points, including origin points, limit points, start points, and endpoints are defined using

the Point Constructor.

Defining

Vectors

All direction, reference, and destination vectors are defined using the Vector Constructor.

Features created using the Thru option of Face Association define vectors in I, J, K

components mapped to the Absolute Coordinate System. You can enter I, J, K components

as real values or expressions.

Target Solid The solid body on which you create new features. If there is only one solid body displayed,

the system selects the target solid for you. Otherwise, you must select the body you want to

identify as the target.

Boolean

Operations

When you create primitives and swept features, you must choose to either create a new

target solid or perform a Boolean operation with respect to an existing target solid.

Undo Allows you to back up, one step at a time, to an existing previous state. Undo appears on

the main menu bar under Edit, and on the MB3 popup menu.

Object Selection

In some options, such as Extrude or Revolve, where several objects are to be swept, associativity to

sketches or nonsketch curves is created with the swept objects or with the path in which they are swept.

This means that when you edit the curves, the solid body is updated automatically.

Boolean Operations

When you create primitives and swept features, you can choose to perform a Boolean operation with

respect to an existing target solid.

Unite Lets you join the new feature with a target solid. The new solid body will contain the combined

volume of the target solid and the new feature.



Subtract Lets you remove the new feature from a target solid.

Intersect Lets you create a solid body from material that is common to both the new feature and the

target solid.

Here are a few things to keep in mind with Boolean operations:

When you attempt to add a swept feature to a solid body, ensure that the feature you defined

comes in contact with the target solid.

When you attempt to subtract or intersect a swept feature to a solid body, ensure that the feature

you defined intersects the target solid.

If the new feature does not come in contact with the current target solid and can be a standalone

solid body, choose to Create a new target solid.

If you perform a Boolean operation between a view dependent solid body and a model solid, the

target solid controls the resultant body. If you perform an undo, both bodies are restored

Color and Shading Variances

It is possible that while performing operations on solid bodies, some faces may acquire colors different

from that of the parent solid. If this occurs, affected faces of the solid body may have different colors in a

high quality shaded image. You can easily correct this by performing an Edit Object Display Type Face Select All, and then setting all faces to a single color. The shaded image then displays correctly.

Invalid solid bodies may not shade. If shading of a solid body fails, use Analysis Examine Geometry to see if the body is valid.

Rows and Columns

Many of the sheet creation options use the concept of rows. A row defines the U direction of the sheet

body. For example, if you are creating the sheet by specifying a collection of points or poles, a row is

simply a collection of points running in roughly the same general direction. Similarly, if you are creating

the sheet through a collection of curves, each curve you select defines a row.

A column is defined by the set of points of a curve running roughly perpendicular to the rows. This

defines the V direction. See the figure below.

Bodies are pictorially represented by a U-V grid. The grid consists of lines that create a net conforming to

the curvatures of the body. The grid is only a display feature that provides a visual representation of the

body. The density of the U-V grid has no relationship to the mathematical accuracy of the body. The

density of the grid is user-defined and may be modified to best represent the body. To properly display a

complex body requires many grid lines, while a flat body requires very few.



You can change the grid display for all subsequently created bodies using the Grid Lines options on the

Modeling Preferences dialog.

Degrees

Degree is a mathematical concept - it actually refers to the degree of the polynomial that is used to

describe a surface. NX uses similar concepts to define sheet bodies. Each sheet body has a degree in the U

direction and a degree in the V direction.

The degree of a sheet (in either direction) must be between 1 and 24. However, we recommend that you

use cubics (a degree of 3) when creating sheets. Creating lower degree sheet bodies results in faster

performance during subsequent operations such as machining and display. Using higher degree sheet

bodies reduces the chance of transferring data to other systems which may not support them. Also, the

creation of a high degree sheet through many points may lead to unpredictable results.

A higher degree sheet is "stiffer" in the sense that you have to move a pole a long way to produce any

appreciable change in the shape of the body. Lower degree sheet bodies are more pliable, and tend to

follow their poles much more closely.

Poles roughly correlate to the degrees of freedom of the sheet. To increase the degrees of freedom for a

sheet, you can:

Increase the number of points per patch (that is, the degree)

Increase the number of patches for the sheet body

Patches

A patch is a portion of a sheet. Using more patches to create a sheet gives you more localized control over

the curvature of the sheet.

When creating sheets, it is best to minimize the number of patches used to define the sheet. Limiting the

number of patches improves the performance of downstream applications and produces a smoother sheet.

Smart Bodies

Smart bodies are bodies that "remember" their creation data (strings, tolerances and parameters).

Any change to the geometry or expressions used to create a smart body cause the body to regenerate. Any

solid features created from smart bodies are updated as well. Thus you can create multiple levels of

associativity. For example, you can use sketch geometry to create a free form body, then use that resulting

body to create a feature. You can then edit the feature by editing the original strings (that is, the sketch

geometry).

Information Options

You can check the validity of a free form feature with the Analysis Examine Geometry options.

Use Analysis Minimum Radius to find the smallest radius of curvature (including tiny hooks or reversals in the surface) in a face or collection of faces.

You can use Information Feature and Information Object to display information about a free form feature.



Sheet vs. Solid Creation

When using the Swept, Through Curve Mesh, Through Curves, Ruled and Section free form feature

creation options, the type of body (solid or sheet) created depends on the Body Type modeling preference.

For example, if the Body Type is set to Solid Body, and the selected section strings form closed loops,

and the first and last section string are planar, a solid body is created.

When you create a free form feature, the type of body created is displayed in the Status line.

Note If the Body Type is set to Solid Body, but one or all of the selected section strings do not form a

closed loop, or one of the end section strings is not planar, a sheet body is created.

Boolean Operation

If another body already exists (whether a sheet body or a solid body) and you create a free form feature,

you must specify the Boolean Operation used to combine the two bodies - Create, Unite, Subtract or

Intersect.

There are two restrictions when it comes to Boolean operations:

You cannot split a target body into two pieces by subtracting another body.

You cannot create a nonmanifold solid body by, for example, attempting to Unite two sheet bodies.

a. Horizontal Reference, Parameter Values, Positioning Features, Associativity Rules

Horizontal Reference

Some features require a horizontal reference, which defines the XC direction of the feature coordinate

system. You can select an edge, face, datum axis, or datum plane as the horizontal reference. The

horizontal reference defines the length direction of those features that require a length, including Slot,

Pocket, and Pad.

Note For these options, you are not required to select a Horizontal or Vertical Reference during the

positioning of the feature - it is already defined.

Parameter Values

Each feature type requires you to enter values which define the dimensions necessary for that particular

feature. These are sometimes referred to as the feature's parameters.

Positioning Features

You can position a feature (or a sketch) relative to existing solid body geometry or datum planes. This is

done by creating positioning dimensions (sometimes called dimensional constraints), that control the

location of a feature relative to some existing solid body geometry or datum planes.

You can complete a feature without constraining its location by choosing OK before choosing a

dimension type. The feature can later be positioned or moved using options found under EditFeature.

If it is necessary to position a feature using geometry that has been modified creating a conflict (e.g., a

blended edge), you can:

Suppress the blend, using Edit Feature Suppress Feature. Create, position, and reorder the new feature to come before the suppressed blend.



Unsuppress the blend, using Edit Feature Unsuppress Feature.

Associativity Rules

The following associativity rules apply to the creation of features:

A feature created using the Thru option is associated to the faces selected as the thru faces. The

feature remains a thru feature whenever the target solid is changed (see the figure below).

Positioning dimensions create an associativity between the feature and the target solid. The

dimensions lock the feature at a desired location. The location of the feature can be changed by

simply editing the positioning dimensions that constrain the feature (see the figure below).

Note Editing the solid body does not change the location of a feature. You can change the feature's

location by:

Editing the feature's positioning dimensions,

Moving an unconstrained feature,



Controlling positioning dimension values with expressions.

2. Positioning Methods

When you are creating features and sketches, there are times when the Positioning Method dialog

displays, to let you position the feature or sketch relative to other geometry.

Note You only see those positioning methods that are valid for the feature operation on which you are

currently working.

Note For Boss features, the Perpendicular positioning method is the default. For Boss features, you can

edit and rename the positioning dimensions directly on the Positioning dialog.

a. Position a feature or sketch

You can position a feature or sketch relative to existing curves, solid geometry, datum planes, and datum

axes. This is done by creating dimensional constraints, known as positioning dimensions, that control the

location of a feature or sketch relative to some existing curves, solid geometry, datum plane, or datum

axis (see the figure below).

Note The types of curves that are selectable may be limited, based on the type of positioning dimension

being defined.

Positioning dimensions are associated to the geometry used to create them. If you move or delete

geometry, the associated positioning dimension is also moved or deleted.

To position a feature or sketch, you must:

1. Choose the positioning dimension type. 2. Select the objects to dimension. 3. Enter the new value for positioning. 4. Choose OK to reposition the feature or sketch.

There are nine dimension types that can be used to constrain the location of a feature.

When selecting the objects to dimension, you must select one of the objects from the target solid, curve,

or datum and the other from the feature or sketch. When you position a boss or hole, the system

automatically selects the object on the feature (the arc center) for you.



Selection of objects varies with the type of dimension you wish to create. For example, if you want to use

edges for a horizontal dimension, you must select their endpoints.

When specifying an endpoint, you must select an edge that connects with that point, between the edge's

midpoint and the intended point. For example, in the figure below:

If you select the edge (bold) between the midpoint and point A, point A is selected.

If you select the edge (bold) between the midpoint and point B, point B is selected.

For those positioning dimensions that require the selection of points, the points must be part of the solid

body (i.e., midpoints, endpoints, arc centers, tangency points).

If it is necessary to position a feature using geometry that has been modified, creating a conflict (such as

with a blended edge), you can:

Suppress the blend, using Edit Feature Suppress Create, position, and reorder the new feature to come before the suppressed blend

Unsuppress the blend, using Edit Feature Unsuppress

Once you have added all the constraints needed to locate the feature or sketch, the feature is repositioned.

The positioning dimension can be edited, allowing you to change the location of the feature at any time.

For more information, see the section on Edit Feature Edit Positioning Dimension.

Identify Solid Face

In some cases when using points for positioning, you can dimension to a cylindrical, conical, or toroidal

face by first choosing Identify Solid Face.

Horizontal or Vertical Reference

When creating horizontal and vertical dimensions, you may be required to define a Horizontal or Vertical

Reference by selecting a linear edge, a solid face, or a datum axis or datum plane. A Horizontal Reference

defines the horizontal direction for dimensioning the feature's location. A Vertical Reference defines the

vertical direction for dimensioning the feature's location.

When using a face or datum plane for a Horizontal or Vertical Reference, the reference is formed by the

intersection (a curve) of the selected face or datum plane and the selected planar placement face.



If the system determines that no references can be selected as a Horizontal or Vertical Reference, it

constructs a default reference.

If you are positioning a sketch, the Horizontal or Vertical Reference has already been selected and is not

requested at this time.

Note Whenever a feature whose edge/face was used as a horizontal or vertical reference is deleted, any

Horizontal or Vertical positioning constraints associated with the reference are also deleted.

b. Techniques for Positioning Methods

Editing Edges Used For Constraints

When you select an edge of the target solid to constrain the feature to it, the system creates a curve that

matches that edge. This curve is linked to the target solid. If you modify the edge (for example, by adding

a blend), the constraint is maintained to the original edge (see the figure below).

If you create a blend and then suppress it, the edge that was blended is redisplayed. If, after suppressing

the blend, you position a feature relative to that edge and try to unsuppress the blend, you will get a

warning that the positioning dimension will be deleted. You should cancel the unsuppress operation,

reorder the blend after the feature that is positioned relative to the edge (with Edit Feature Reorder), and then unsuppress the blend.

Note You cannot position solid primitives using positioning dimensions.

Directional Axis (Machining)

When positioning a feature or sketch on a datum plane, a machining (tool) direction axis is displayed.

You can accept the viewed direction or flip it. This accepts the current state of the feature or flips the

feature to the other side of the datum plane.

In the figure below, you can see a thru hole being created from the datum plane to the outer face of the

cylindrical pipe. The system displays the tool direction (#1). If you accept the displayed tool direction, the

thru hole is created as shown by the solid lines. If you choose to flip the displayed tool direction (#2), the

thru hole is created as shown by the dashed lines.



Positive Direction of Constraint

Once you have selected the geometry for a constraint, the positioning dimension is created and displayed.

The initial dimension indicates the positive value direction for the constraint.

Full Constraints

When creating positioning dimensions for use in relative positioning, you may need to use more than one

constraining dimension to fully constrain the location of a feature or sketch. A feature or sketch can be

constrained using any combination of dimensions. You should decide which dimension best suits your

design.

Note NOTE: When constraining a feature, you should consider the relationship of the feature to the target

solid. Those relationships that need to remain constant or be controlled should be constrained. In

other words, the location of the feature to the target solid can be controlled using positioning

constraints.

For example, in the figure below, the feature's location is constrained using two dimensions. If the solid

body is edited, the feature's location relative to the selected target edge is maintained.



Position to a Datum

When positioning a feature or sketch to a datum plane or axis, you cannot use positioning dimensions that

constrain a point to a point, such as a Horizontal, Vertical, and Parallel dimensions. You can only use

dimensions that constrain a line to a point, such as a Perpendicular dimension or a line to a line, such as a

Parallel at a Distance dimension.

If a datum plane is selected, the system projects the datum plane until it intersects with the planar

placement face of the target solid. The intersection between the datum plane and the target face forms a

line, which is used to constrain the feature or sketch.

Position to a Curve

When prompted for the target edge, in many cases you can select an existing curve.

Positioning to a curve can be useful when you want a feature's position to remain relative to another

feature's position on a different part. For example, if you wish the position of a boss on one part to match

a hole's position on a second part, first create an EXTRACTED_CURVE feature from the circular edge of

the hole, then project the curve onto the first part. Create the boss and select the curve as the target edge

for a Point onto Point positioning dimension (see the figure below).

Position by Feature Centerlines

Slots, grooves, and rectangular pads and pockets can be positioned by their centerlines as well as by their

edges. The centerlines appear only when the feature can be positioned or repositioned (for example, just

after feature creation or after choosing Edit Feature and selecting the feature).



If the feature is modified or reattached, its centerlines are automatically updated. Centerlines are

considered part of the feature, and are deleted when the feature is deleted.

A single circular centerline appears for a groove. It is located halfway between the top and bottom edges

of the groove, and is equal to the diameter of the groove. Each of the other features has two centerlines,

one horizontal and one vertical.

To position to a centerline, select the target solid edge and then the centerline. See the figure below for an

example.

Note You can also select an existing curve, on or off the same part, when prompted for the target edge.

Position a UDF

Positioning a user defined feature (UDF) works the same as positioning any other feature, except you

have an additional option: Reverse Normal, which flips the user defined feature about its placement tool

face 180 degrees.

Note A user defined feature must be created using one of the Boolean operations under Attachment

Method in order for Add Positioning Dimension to be available when the UDF is imported.

Position a Thru Slot

When positioning a thru slot, do not dimension to the end arcs of the slot.

Position a Groove

When positioning a groove, you only have to position the groove along the axis of the cylindrical target

solid. No positioning dimension menu appears. Instead, you only need to specify a horizontal dimension

along the axis, as shown in the figure below. This is done by selecting a target solid edge and then a tool

(i.e., the groove) edge or centerline.

Note You can also select any existing curve, on or off the same part, when prompted for the target edge.



c. Horizontal

The Horizontal method creates a positioning dimension between two points.

A Horizontal dimension is aligned with the Horizontal Reference, or is 90 degrees from the Vertical

Reference.

d. Vertical

The Vertical method creates a positioning dimension between two points.

A Vertical dimension is aligned with the Vertical Reference, or is 90 degrees from the Horizontal

Reference.



e. Parallel

The Parallel method creates a positioning dimension which constrains the distance between two

points (e.g., existing points, entity endpoints, arc center points, or arc tangent points) and is measured

parallel to the work plane.

In the figure below, a pad is dimensionally constrained on a block. You can imagine a parallel dimension

as a rope joining two points at a specified distance. It takes 3 "ropes" to locate this feature.

When you create a parallel or any other linear type dimension to a tangent point on an arc, there are two

possible tangency points. You must select the arc near the desired point of tangency.

f. Perpendicular

The Perpendicular method creates a positioning dimension which constrains the perpendicular

distance between an edge of the target solid and a point on the feature or sketch. You can also position to

a datum by selecting a datum plane or datum axis as the target edge, or any existing curve (which need

not be on the target solid).

This constraint is used to dimension linear distances that are not parallel to the XC or YC axis. It only

locks the point on the feature or sketch to the edge on the target solid, or to the curve, at the specified

distance.



Note For Boss and Hole features, the Perpendicular positioning method is the default. In addition, for

these features, you can edit and rename the positioning dimensions directly on the Positioning

dialog.

g. Parallel at a Distance

The Parallel at a Distance method creates a positioning dimension which constrains a linear edge of

the feature or sketch and a linear edge of the target solid (or any existing curve, on or off the target solid)

to be parallel and at a fixed distance apart.

This constraint only locks the edge on the feature or sketch to the edge on the target solid or the curve at

the specified distance.

h. Angular

The Angular method creates a positioning constraint dimension between a linear edge of the feature

and a linear reference edge/curve at a given angle.



Be sure to select the lines to dimension at the proper location. Each line has three control points, one at

each end and one at the exact center. The angle created depends on which side of the center control point

you select.

The figure below shows two lines with their center control points highlighted by asterisks (*). The 33_25'

angle was created by selecting the lines at the positions indicated by A. The 146_36' angle was created by

selecting the lines at the positions marked B. As you can see, selecting the smaller line at a position left of

the center control point creates the complementary angle.

i. Point onto Point

The Point onto Point method creates a positioning dimension the same as the Parallel option, but with

the fixed distance between the two points set to zero

This positioning dimension causes the feature or sketch to move so that its selected point is on top of the

point selected on the target solid.

j. Point onto Line

The Point onto Line method creates a positioning constraint dimension the same as the Perpendicular

option, but with the distance between the edge or curve and point set to zero

Note The selected point must be on the feature and the line must be on the target solid as an edge, curve,

or associated datum plane.

This positioning dimension causes the feature or sketch to move from its selected point, normal to the

edge or curve selected on the target solid, until the point is on the edge.

This constraint only locks the point on the feature or sketch to the edge on the target solid.



k. Line onto Line

The Line onto Line method creates a positioning constraint dimension the same as the Parallel at a

Distance option, but with the distance between the linear edge of the feature or sketch and the linear edge

or curve on the target solid set to zero.

Note If you choose a curve when prompted for the target edge, the curve must be linear and must be on

the target solid.

This positioning dimension causes the feature or sketch to move from its selected edge perpendicularly to

the edge or curve selected on the target solid.

This constraint only locks the edge on the feature or sketch to the edge/curve on the target solid.



3. String Selection

Several of the free form feature creation options require that you select curve outlines known as strings. A

string can consist of one or more objects. Each object can be a curve, solid edge, solid face, endpoint of a

curve, or point.

The maximum number of objects in one string is 5000 and the maximum number of strings in one free

form feature is 150 with the exception of the Ruled body, where it is 2 strings.

By default, if one curve of a sketch or projected curves are selected, the system selects the entire sketch or

projected curves.

You can mask the selection of the objects using any of the following:

Solid

Face

Lets you select all the edges of a face at once as objects of a string. You can use this option to

create a bridged free form feature between two existing solid bodies.

Solid

Edge

Lets you select single edges of a solid body as objects of a string.

Curves Lets you select single curves, sketch and non-sketch curves alike, as objects of a string.

Chain

Curves

Lets you select a chain of sketch or non-sketch curves. For certain functions in Curve and

Feature creation, Chain Curves also support the added following features:

You can use Chain Curve to select not only curves but edges for selection profiles. You

can also select edges from different faces for the chain.

When a chain encounters multiple edges at vertices, the direction of the chain proceeds

along the path with the least angle.

You can auto-chain an entire profile by double-clicking a segment of the chain of

curves or edges.

These special features for Chain Curves are available with Join Curve, Offset Curve, Swept,



Ruled Surface, Through Curves, Through Curve Mesh, Section, Extrude, Revolve, Tube, and

Sweep Along Guide.

Point Lets you select a single point as a string.

Chain Curves lets you select a chain of sketch or non-sketch curves.

You can select a contiguous chain of curves without selecting the end of the chain by selecting the start

curve and choosing OK. This can be helpful in determining whether a set of linked curves actually are

connected without gaps.

Note The system stops selecting chained curves if there is a gap between any of the curves.

Point lets you select a single point as a string. During the selection for f'irst and/or last primary strings of

Through Curve Mesh option, or the first section string of the Ruled option, you can select an existing

point, or endpoint of a curve, as an entire string.

When you select a point as a string, the system automatically continues to the next string selection.

Point selection is available for Ruled free form feature creation only if the Alignment Control is set to

Parameter or ArcLength.

Selecting Section Strings

As each section string is selected, a direction vector is displayed, indicating the start of the string selected.

The direction vectors are used to line up the section strings, to prevent the resulting body from twisting

(see the figure below).

You must start selecting all the section strings from approximately the same location (from the same end),

as shown in the figure below.



Objects in each section string can be selected in an arbitrary order. The selected objects are sorted and

ordered based on the first object selected. After you have selected all the objects for the desired string,

choose OK.

A direction vector is displayed to signify the starting object (the first object selected in the string). When

selecting faces as section strings, the starting object is the edge of the face closest to the location where

you selected the face, as shown in the figure below.

Note The starting location of each section string is point aligned.

To terminate the selection of a string, you can do one of two things:

You can respecify the starting object of the previously selected string by simply selecting an

object within that string. If you choose to respecify the direction vector, the system erases the old

vector and displays the new direction vector.

You can start selecting new objects for the next section string.

For Swept, Through Curves, and Ruled free form feature options, if the selected section strings contain

any sharp corners, it is recommended that you use the By Points alignment at the sharp corners to

preserve them. The system will create separate faces joining at the edge formed by the sharp corners. You

can also define the tolerance to be 0.00 for an exact fit of the free form feature to the sharp corners, which

is convenient for section string of similar shape (for example, rectangular section string to rectangular

section string).

Otherwise, a high curvature, smoothed corner body is created to approximate these sharp corners. Any

subsequent feature operations performed on these corners or faces (e.g., blends, hollows, or Boolean

operations) may fail due to the curvature.



Error Messages

The following error messages may be displayed during string creation.

All the selected objects in a string must be contiguous and all inner loops are ignored except with the

Bounded Plane option. Otherwise, the following error message is displayed.

Gaps in String or Multiple Loops

The following message is displayed if the selected faces/edges contain split edges - such faces/edges

cannot be used as strings.

Split Edges are Found

The following error is displayed if a face(s) selected as a string is missing during updating.

Missing Face Referenced by String Object

The following error is displayed if an edge(s) selected as a string is missing during updating.

Missing Edge Referenced by String Object Unable to Reference Edge

The following error is displayed if, for certain V direction strings (i.e., guide string and cross strings),

tangent objects were required but not defined.

Tangent Objects Required For V Direction String

The following error is displayed if you are using By Points alignment and the number of objects in a

string is not greater than one.

Aligned By Points Required More Than One Object In A String

The following error is displayed if the selected string is not coplanar (this is required for Bounded Plane).

String Objects Not Coplanar Coplanar String Objects Required With Inner Loop

The following error is displayed if the selected string does not form a closed loop (this is required for

Bounded Plane).

String Objects Not Closed

The following error is displayed if the starting object (i.e., the first object selected in the string) on the

outer loop is too close to an inner loop (string). Try reselecting the outer loop in another location away

from the inner loop.

Invalid Starting Object On Inner Loop Of A String

The following error is displayed if invalid string objects are detected. Such objects may split the string

into multiple pieces.

Invalid String Objects

The following error is displayed if a string does not contain at least one object or because the tolerance is

greater than the string length.



String Contains No Object

The following error is displayed if the selected starting object of a string is a sketch reference line/arc.

Starting Curve Cannot Be A Reference Object

a. Snap Point options

Snap Point options are found on the Selection Bar to aid you in specifying points and point locations

during the creation and editing of geometric objects. For full details, see Snap Point options on the

Selection Bar in the NX Fundamentals help.

4. Selection Intent in Feature Modeling

Selection Intent is a Selection Bar tool that lets you select and group multiple curves, edges and faces into

collections with rules defining how a feature can use them. You choose which rules to use based on what

you intend the feature to do. All Modeling commands that use Selection Intent have customer defaults for

the initial Selection Intent rules.

Note For full details on Selection Intent rules, see Selection Intent rules and options on the Selection Bar

in the Fundamentals help.

Selection Intent makes selection more efficient, and increases the robustness of updates during edits by

relying on higher level objects that capture your intent (instead of low level curves and topology). If you

later change the members in a collection during an edit, its rules remain intact, letting the feature update

properly.

The following figure shows a model with a draft that was created with the Selection Intent Tangent

Faces rule. The left view shows the original model, and the right view shows the model after material and

new faces are subsequently added. Even though some of the original faces were replaced, the draft still

updated successfully, because it followed the Tangent Faces rule.

When Material is added to the model on the left, the draft still updates correctly (right)

If the draft had been defined with single-selected faces instead of the Tangent Face rule, the draft would

have failed to update during this edit.

The following figure shows a second example where Selection Intent allows a draft feature and a hollow

feature to both update successfully when the model is edited.



Selection Intent allows successful update after changes to the model (before - left, after - right)

Where do I find it?

Selection Intent options appear on the Selection Bar for commands that support it.

a. Use Selection Intent during object selection

1. Open the creation or edit command for a feature that supports Selection Intent. 2. Choose the rule for the collection needed by the feature you are creating (such as Face Rule or

Curve Rule). If the rule is for a chain, select the base or seed object first, and then the objects that

relate to it.

b. Selection Intent available with option and type settings

Selection Intent is available from within a command for certain option and type settings.

Specify Point option, when the type is set to either of the following:

o Point on Curve/Edge

o Intersection Point Specify Vector option, when the type is set to:

o On Curve Vector Specify Plane option, when the type is set to:

o Tangent Plane

c. Simple use of Selection Intent

In this simple example, the Connected Curves rule is used to select a connected string of non-associative

curves in one step for the section of a Sweep Along Guide feature.



Connected Curves rule selects a string of curves for the section

The Tangent Curves rule is used to select 3 spline curves for the section guide.

Tangent Curves rule selects 3 spline curves for the section guide

This results in the Sweep Along Guide feature shown below.



Resulting Sweep Along Guide feature

If you edit the section or guide curves used by this feature, it will still update correctly. For example,

trimming away the curve fillets from the section and one of the splines from the guide results in a

successful update.

Result after trimming away the section fillets and removing one guide spline

d. Selection Intent collection building

When you need to use chaining to build a section or collection of curves or edges for the feature you are

creating:



The Curve Rule is available for collecting and section building.

The Type filter on the Selection Bar changes to Curve, Edge or Any, based on the needs of the

feature.

The cursor changes to Curve Collecting to show you are in wireframe collection mode.

On selecting a curve or an edge, Selection Intent begins building the profile or section based on

the currently specified Curve Rule and More options.

When you start a chain, the first selected curve or edge becomes the seed object. The chain includes all

curves and edges currently visible. Chaining proceeds until no other chaining candidates can be found or,

multiple directions are encountered and the chain stops, letting you choose the next segment of the chain.

Complete the chain using the middle mouse button.

For examples of using Selection Intent to build a section profile, see Selection Intent - Building A Section.

Selection Intent smart deselection

Once a chain is selected with a specific rule, you can deselect specific objects from the chain. Smart

deselection captures the intent of deselecting the chain. This ensures that during an update the chain can

honor the deselections with similar intent.

Smart deselection works for all curve and face rules, except for the Tangent and Connected curve rules.

Depending on the context, smart deselections are inferred in the following ways:

For face chains and direct edge chains, if you deselect objects while editing a chain, it is inferred

that you want to remove these specific items from the chain. During subsequent updates, if the

objects are captured again, they are removed from the chain.

For merged chains, any object that you deselected in the earlier chain is removed, unless you

select it while creating another chain.

The detailed view of the Dependencies panel in the Part Navigator shows the removed objects in

the Removed Objects folder, in the Chain folder, under Section. In every subsequent update,

normal rule propagation is done and the stored deselected objects are removed from the section

after updating the chain.

For sections using the Stop at Intersection or Follow Fillet, if you deselect a single object, the

entire chain is deselected.

The detailed view of the Dependencies panel in the Part Navigator shows the start and end limits

for Stop at Intersection in the Intersection Limits subfolder, in the Chain folder under Section.

For more information about the representation of Selection Intent in the detailed view of the

Dependencies panel in the Part Navigator, see Dependencies panel.

e. Specify a region with Selection Intent

The following example shows how regions can be used with Selection Intent to create a Draft feature.

Note For specific procedures on creating a draft see Draft procedures.

1. Open the Draft dialog box and do the following:



a. For the Type, select From Plane. b. Select a Stationary Plane for the draft, one that will not move and from which the draft

will propagate. In this example, we select the top, horizontal face.

2. Set the Face Rule to Region Faces and select a seed face, as shown below.

Note For an explanation of Face Rules, see Selection Intent options on the Selection Bar.

3. Once you specify the seed face, Selection Intent switches the Face Rule to Single Face, to let you select one or more region boundary faces. In the figure below we select three boundary faces.

4. Click the middle mouse button to complete the region, from which the draft faces are automatically selected.



5. Click OK or Apply to create the Draft feature.

If you later edit, add, or delete any of the faces, the original Selection Intent rule remains effective, and

the draft updates correctly, as shown below when the source faces are changed.

f. Building a section in Selection Intent

This page shows some simple examples of how to build a section using Selection Intent's section builder

options. See Selection Intent rules and options and Selection Intent Collection and Section Building for

more information.



Draft example

In the figure below we use the Curve rule, Tangent Curves to add four collections of curves (1 through

4) to the section (shown below in red).

Tangent Curves rule to select a profile of curves

The collection of section curves produces the draft body shown below.

Draft body feature

If we edit, add or delete any of the section curves, the tapered body still updates correctly (below).



Editing the section curves later (1) allows the draft body to update successfully

Extrude example

Following is a simple example of how you can build a section with Selection Intent's section builder to

create an extrusion.

In the figure below we use the Curve ruleTangent Curves with the Stop at Intersection option to add

four collections of curves (1 through 4) to a section (shown below in red). Each collection stops at an

intersection, giving you the opportunity to specify which way the section should go next.

Tangent curves rule to select a collection of curves

g. Modifying Selection Intent collections and sections

You can modify members of a Selection Intent collection the same as you would a list of selected objects.



Shift/Click Deselects Intent objects and removes them from the collection.

click Selects objects and adds them to an Intent collection.

Shift/Delay/Click Opens a QuickPick cursor and a dialog box to let you select between the object and the

collection that includes that object (All of Intent).

Removing objects from a collection causes the loss of the rule and the collection becomes a simple list of

objects.

If you edit a collection that is used by a feature, the old objects may not map properly to the new. In that

case, the Replacement Assistant may appear to let you resolve the new mappings.

Using right-click to redefine a collection

You can right-click an object in a collection that you have selected with Selection Intent and redefine the

collection's intent rule.

For example, when you select an initial edge with the Face Edges rule you build a collection of faces

using that rule and based on that first edge. If you then right-click one of the selected objects in that

collection and change the rule to Tangent Curves, the initial collection is replaced by a new one that uses

the new rule, with the new object becoming the seed.

Using right-click option menus to change the intent method also changes the currently active method in

the toolbar.

The intent rules on the right-click option menu will not always match those on the selection toolbar, due

to rules requiring multiple object selection.

h. Selection Intent cursors

As you initiate a Selection Intent action, the cursor changes to signal the collection mode and the current

operation.

Curve Collecting

Face Collecting

Region Specification

Chain Between - Start

Chain Between - End

5. Replacement Assistant

If you edit a collection of objects that is used by a feature, the software may not always be able to map the

old objects into the new without possibly breaking associativity to dependent objects. In these cases, the

Replacement Assistant may appear to let you may map the objects during the modification.



Use the Replacement Assistant to define the equivalences between faces and edges of the current object

and the replacement object.

For example, if you edit the section of an Extrude feature and the software determines that the new

section objects may need to be identified in relation to the objects they are replacing, the Replacement

Assistant appears at the conclusion of the edit.

A Selection Intent Mapping with Extrude

The original Extrude created with a number of collections using the selection intent Connected

Curves rule and the Stop At Intersection option.

Two selection intent Connected Curves collections deselected during edit.

Two new Connected Curves collections selected.

The new extruded body, after the mappings are completed using the Replacement Assistant.

The Replacement Assistant is also used during interpart and WAVE modeling.

Where do I find it?

The Replacement Assistant dialog box appears automatically when your edit of features clarification of

how new objects introduced in the edit are to replace old removed objects.

a. Map objects during modification

When you click OK to complete the editing of a Selection Intent section for a feature that supports the

Replacement Assistant, an information dialog box may display stating that your edit has the potential of

affecting downstream features, and you are asked if you want to provide the mapping between the old and

new sections.



If you decide to do the mapping, the Replacement Assistant dialog box opens, and a two-view display

shows the original section displayed on the left and the new section on the right.

in other cases, the Replacement Assistant may appear automatically at the conclusion of an edit.

1. Select the objects you want to map in the left view (old-section view).

For each object you select, an entry is added to the Replacement Assistant with a question mark

next to it.

2. Select the objects you want for the new mappings in the right view (new-section view).

For each new object you select, a question mark in the Replacement Assistant changes to a green

check mark. You can map as many of the objects as you want (you do not have to map all objects).

3. Click OK to complete the mapping of objects from old to new.

Note For details and more information, see Replacement Assistant in the Assemblies Online Help.

E. Expressions

Expressions are arithmetic or conditional formulas that define some characteristics of features.

You can use expressions to control the relationships between the features of a part, or between parts in an

assembly. For example, you can express the thickness of a bracket in terms of its length. If the length of

the bracket is altered, the thickness automatically updates. You can use expressions to define and control

many dimensions of a model, such as the dimensions of a feature or a sketch.

The formulas within expressions can include a combination of variables, functions, numbers, operators,

and symbols. You can insert expression names in the formula strings of other expressions.

There are two basic kinds of expressions:

User expressions, those you create (also known as user defined expressions).

Software expressions, those the software creates.

User expressions can have plain language names. Expressions created automatically by the software are

named with a number, preceded with a lower case "p", such as "p53".

Here are some examples of expressions, their formulas, and their resulting values:

Expression name Additional software expression name Formula Value

width - 22 22

length - 5*width 110

p39 (Flange(6) Bend Allowance Formula) (p26+(p64*0.44))*rad((-p24)) 18.849537

p16 (Extract Region(7) Angle Toler) 45.0 45

Where do I find it?



Menu ToolsExpression

Part

Navigator

Right-click an expression in the Part Navigator, either in the Main panel or Details panel,

and choose Edit in Expression Editor

Dialog boxes

From supported Modeling dialog boxes, click parameter entry options and choose

Formula.

1. User expressions

User expressions are any expression that you create yourself with the Expressions dialog box.

For example, you could create an expression named "width" with a formula string of "5.0". You could

then use this expression to define the dimensions of a block by entering "width" in the appropriate

parameter entry field.

You can create expressions based on measurements and interpart references.

Here is a sample of some user-defined expressions:

Expression Name Formula

width 22

length 5*width

diameter width/3

position if (width



The Expression dialog box may display additional parameter text for system expression names, but it is

not part of the actual name. This additional text follows the name and describes the feature and parameter

option it is associated with. For example, the system expression p5, shown below, is for the diameter of a

simple hole feature with a time stamp of 4:

p5 (SIMPLE_HOLE(4) Diameter)

System expressions are automatically created during many Modeling operations:

Sketch Dimensioning - An expression is created for each dimension (i.e., p2=3.5436).

Positioning of a Feature or Sketch - An expression is created for each positioning dimension.

Feature Creation - Expressions are created for the creation parameters of many features (such as

extrusion start and end limits, revolution angle, and hole depth).

Creation of Mating Conditions or Assembly Constraints.

Here are some examples of system expressions:

Expression Formula

p28 (Extrude(14) Start Limit) 15

p3 (Bridge Curve)(6) Match Point 2) 21

p6 (Studio Surface 2X2(11) Angular Tolerance) 0.5

You can rename system expressions.

3. Expressions options

Listed Expressions

Categories Lets you choose a category to filter the expressions displayed in the list window.

Expression names are shown in the list window with no regard to case.

Select from the following categories:

User Defined

Shows only expressions that you have created yourself.

Named

Shows only expressions that you have created and those you have not created

but have renamed.

Unused Expressions

Shows only those expressions that are not being used by any objects in the part

file.

Object Parameters

Shows only those expression parameters for a feature selected in the graphics



window or Part Navigator.

Measurements

Shows all measurement expressions in the part file.

Filter by Name

Used with the adjoining filter box to let you enter or select a string of

characters to show a subset of expressions by their names.

Filter by Value


characters to show a subset of expressions by their values.

Filter by Formula


characters to show a subset of expressions by their formula.

Attribute Expressions

Shows all part and object attribute expressions present in the part file.

All

Shows all expressions in the part file.

Filter box Lets you enter a filter string. The string is evaluated based on the filter category type

(that is, Filter by Name, Filter by Value, or Filter by Formula)

You can enter an asterisk wild-card to filter the list further.

Spreadsheet

Edit

Transfers control to the NX spreadsheet function, which you can use to edit

expressions. When control is transferred to the spreadsheet function, NX is idle until

you exit from the spreadsheet.

Note Legacy parts with Geometric expressions are not listed in the

spreadsheet.

The spreadsheet substitutes the string q... for each quote (), and a question mark (?) for each colon (:) it encounters. You may therefore

wish to avoid using this option with interpart expression filenames that

contain these characters. For example, an interpart expression with the

formula mypart::myexpression would appear in the spreadsheet as q...mypartq...??myexpression.

Import

Expressions

from File

Reads a specified text file containing expressions into the current part file.

There may be times when you have expressions in the text file that have the same

name as expressions already in your part file. When this conflict occurs, the system

either keeps the existing expression or replaces it with the expression in the text file.

You control how expression name conflicts are handled with one of the options shown



below.

Replace Existing

Supersedes the existing expressions that have the same name with expressions

contained in the text file.

Keep Existing

Choose if you do not wish to replace the existing expressions by any

expression that has the same name in the text file. This setting lets you import

only those expressions that do not conflict (do not exist in both files).

When you use the Keep Existing setting, the system reads the specified text

file and attempts to add each expression to the list. If there are conflicts

(expressions with the same name) found during the transfer, an error message

appears. After the transfer is complete, you can choose Accept to keep the new

list or Undo to restore the original set of expressions.

As an example, if an expression of the same name exists in your active part and

in the text file being imported, one of the following scenarios occurs:

If you choose Replace Existing, the expression in the imported text file

replaces the existing expression in the active part.

If you choose Keep Existing, the expression in the active part is kept

and the expression in the text file is ignored.

Delete Imported

The Delete Imported option lets you remove multiple expressions from your

part file. When you choose this option, the system looks at a text file that

contains a list of expressions and deletes any expression in the part file that has

the same name.

This option may be used in one of the following two ways:

Export the list of expressions to a text file. In the text file delete all of

the expressions that you want to keep. Import the list using the Delete

Imported option.

Create an empty text file. Enter into the text file all of the names of the

expressions that you want to delete. (You do not have to enter the entire

expression; just the name). Import the list using the Delete Imported

option.

With either of these methods, the expressions may be listed in any order. Each

expression that is encountered in the text file is deleted from the Expressions

List in the part file.

Note If the expression is used by the model or by another expression, it is not

deleted.

Note Legacy parts with Geometric expressions, such as p0=distance(40),



cannot be imported.

For additional information and format rules, see Expression Text File Format.

Export

Expressions to

File

Lets you write the expressions in the part to a text file. Choosing this option displays a

file dialog prompting you for the name of the text file. You can choose what

expressions to export using the following options:

Work Part

Exports all the expressions in the work part.

All in Assembly Tree

Exports all the expressions in the work part plus all of its components (the

assembly tree).

All Parts

Exports all the expressions in all parts in the session.

All files used for importing/exporting expressions possess the file extension

".exp".

Note Legacy parts with geometric expressions in a file that is being exported

will become "dumb" expressions (for example, an angle expression,

p0=angle(12) that evaluates to 90.0 will become p0=90.0 in the exported

file).

For additional information and format rules, see Expression Text File Format.

Expressions list box

The list box displays a detailed, sortable list of the expressions in the part file. You can filter the

expressions that appear in the list using the Listed Expressions drop-down menu and by entering filter-

strings. You can browse the graphics window and Part Navigator, selecting features to display their

expressions in the list.

Columns The Expressions list box is divided into the following columns:

Name - The name of each expression or measure.

Formula - Shows the unevaluated right hand side of the expression formula for

each expression. If the expression is a measure the label (Measure) displays.

Value - Shows the value derived by the formula or the measure data. If the

formula uses a different unit than the expression, the value is converted to the

expression unit. If the Type is set to Number, the value is a number. If the

Type is set to String, the value is a string.

Units - Shows the units for the expression or measure, if they exist.

Type Shows the expression type, as defined with the Type option. Comment - Shows the comment for an expression if one has been added by

right-clicking and choosing Edit Comment, or by double-clicking the

Comment column.

Note Comments are not included when an expression is linked to another part



through an Interpart Reference (an interpart expression).

You can sort the listing by the contents of a column by double-clicking MB1 on a

column title.

Icons An icon may display with an expression or measure:

A Lock icon appears next to an expression that is locked, which only occurs

when an overriding expression has been loaded in the session.

A Read-only Icon appears if the expression is read-only.

A Measures icon appears if the expression is a measure.

The Knowledge Fusion adoption icon appears if the expression is

bidirectionally controlled from the Expression editor and Knowledge Fusion.

For all expressions with icons except Lock and Knowledge Fusion, the expression text

is shown in light blue and the expression formula is not editable.

Create, edit, special functions, and controls

Use these fields to create, edit and query expressions and measures.

Type Specifies the expression data type.

Number

Creates expressions using a numeric data type.

When Number is the selected Type, the Dimensionality options list to the

right of the Type box becomes available.

Dimensionality

Use Dimensionality options to specify the kind of dimension to use for new

expressions. All types of dimensions specified by the Units Manager are

shown in the Dimensionality options list.

The most common types of dimensions used with Modeling expressions are:

Length

Distance

Angle Constant (that is, dimension-less, as with the number of holes in an

instance array).

Both the dimensionality and the units you specify for an expression formula

must be correct with regard to the input and the expected output.

For example, if you create a new expression formula named C that multiplies

together two existing length expressions (A and B, created in millimeters) to

get an area (C=A*B), you would set the dimensionality of C to Area and the

units to mm^2. Otherwise, you may get a units inconsistency error.

You must also make sure that the function arguments in your expressions have

the correct dimensionality. The sqrt function, for example, fails with the



argument sqrt(x) when used with the Length dimensionality, because the

software cannot calculate the square root of a Length dimensionality unit. But,

if you write the function as sqrt(x*in) for inches or sqrt(x*1mm) for

millimeters, the function succeeds. (Note that sqrt(x) succeeds when the

dimensionality is Constant instead of Length.)

You cannot change the dimensionality of a system generated expression.

See Units Manager in Advanced Simulation Help for further information.

String

Creates an expression using a string data type.

String expressions return a string instead of a number, and are defined as

double-quoted sequences of characters.

The formula for a string expression can be constant, such as Text entry, or it can be calculated.

For example, the following string expression:

NAME FORMULA

mick y2k+lg+yr+prep+terra

When used with these string expressions:

NAME FORMULA VALUE

lg Light Light

prep from from

terra Home Home

y2k 2000 2000

yr Years Years

Yields this value:

2000 Light Years from Home

The string expression's formula can contain any combination of function calls,

operators, or constants that result in a string when the formula is evaluated.

You can use string expressions to direct a part's non-numeric values, such as a

part description, a vendor name, a color name, or other string attributes.

Boolean

Creates an expression to support alternate logical states using Boolean values

of true or false.

Use this data type to represent an opposing condition, such as the suppression

status for the Suppress by Expression and Component Suppression

commands.



Integer

Creates an expression using a numerical count without units.

Use the this data type in commands that require a numerical count or quantity,

such as Instance Geometry.

Point

Creates an expression by defining a position using X, Y, and Z dimensions.

Formula syntax:

Point(0,0,0)

Use this data type in commands that require the specification or reference of a

position by expression. For example, you could parametrically control a

Revolve axis location, or the minimum distance location of an associative

Measure Distance.

Vector

Creates an expression by defining a direction using Cartesian I, J, and K

coordinates.

Formula syntax:

Vector(0,0,0)

Use this data type in commands that require either the input or the output

(measurement) of a direction. For example, you could parametrically control an

Extrude direction or a Revolve axis direction.

List

Use this data type to streamline NX DesignLogic interactions and provide

additional functionality capable of handling a wider variety of design tasks.

You can use the Extended Text Entry option to conveniently specify list

expressions with comma separated values of any DesignLogic data type as list

expressions using braces {}.

Name Lets you specify a name for a new expression, change a name for an existing

expression, and to highlight and display an existing expression for edit.

Expression names must begin with an alphabetic character, but can be composed of

alphanumeric characters. Expression names can include embedded underscores. You

cannot use any other special characters in an expression name, such as -, ?, * or !.

Note Expression names are not case sensitive, except under certain conditions.

See Expressions name case sensitivity for details.

Expressions names can be in the users supported international language (locale). Both the left hand side (LHS) and the right hand side (RHS) of



an expression support internationalized name strings, as well as

DesignLogic functions and interpart expressions. Note that file names

are not internationalized in NX.

Unit Available only when the Type is set to Number and the Dimensionality to something

other than Constant.

Specifies the unit for the selected dimensionality.

If you change the dimensionality type, the unit also changes.

Formula Use this field to edit the formula for an expression selected from the list, enter the

formula for a new expression, or create a reference for an interpart expression.

You can fill the Formula field the following ways:

Enter an expression formula using the keyboard.

Select an expression from the list window to display its formula, and right-

click Insert Formula.

Click the Functions button to insert a function.

Click one of the Measurements buttons to specify an object measurement from

the graphics window and insert it into an expression.

Click the Create Interpart Reference button to insert an expression from

another part.

You can enter simple units in a formula, such as "3mm". Any necessary unit

conversions display in the Value column of the list window.

If you use different or inconsistent dimensions in the formula, a warning message

displays.

You can also enter statements in scientific notation. The value you enter must contain

a positive or negative sign. For example:

2e+5 for 200000

2e-5 for 0.00002

Note When you open the Expression dialog box from a function's parameter entry

option, you can only edit the formula of the expression you are presently

creating. You cannot use the editor to change existing expressions, although you

can create new ones.

Tip Expressions created for Symbolic Threads that have the Manual Input option off

are restricted in the Expressions dialog box, and are unavailable for change. You

can still edit these expressions by using Edit Feature Parameters, bypassing the Manual Input option. This level of protection has been put in

place to maintain standard values taken from the thread lookup tables.

Extended Text

Entry

Opens a window where you can edit expression strings and add Insert function and

Insert Conditional statements.

Convenient when specifying list expressions with comma separated values of any

DesignLogic data type as list expressions using braces {}.



Accept Edit

Creates a new expression or finalizes the results of an edit on an existing expression.

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