Page 356 - Mastering SolidWorks

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COnTrOllIng SUPPrESSIOn STATES OF FEATUrES 329

Using Expressions
Expressions can also be entered directly into Dimension dialog boxes in the Modify dialog box
and PropertyManager value boxes. The expressions must be composed of numbers and math-
ematical operators. An expression such as
2.375+(4.8/3)-1.1
is perfectly acceptable, as is

1+1/2
or
1 1/2
In the second case in this example, the plus symbol is understood.
Other types of operations are also available, such as ones for changing units in a dimension
box. For example, if you are editing a part in inches and enter 40mm, then SolidWorks performs
the conversion for you. You can even mix units in a single expression such as 4.875+3.5mm,
where the inch part is assumed as the document units.
Unlike equations, SolidWorks does not remember the expression itself, only the final value.
The difference between an expression and an equation is the presence of dimension or variable
names. Expressions can be entered into any place where you enter dimensions for
SolidWorks features.

Controlling Suppression States of Features
You can use the IF statement described earlier in this chapter to control suppression states of
features and components. An example of the syntax is
<feature name> = if(expression, value if true, value if false)
Figure 10.15 shows this type of equation in use. In this case, the features area is in the middle
of the chart in Equations view. To get the feature into the cell, make sure the cell is selected and
click the feature in the FeatureManager or graphics window. Anything in quotes can be selected,
so you don’t have to worry about spelling or syntax. The IF statement reads in English, “If the
spacing is greater than 0.5, then do not suppress. If not, then do suppress.” There’s a little
double-negative thing going on here, but it is the suppression state, not the existence of the
feature itself that you are controlling.
Figure 10.15
Using IF to control
suppression states

You can also use this equation in assemblies to control suppression states of components
(parts and subassemblies).