- [Instructor] Now that I have my die line
and parting surface in the model,
next thing I need to do is create some expressions
or some formulas.
So with every injection molded part ever made,
you need to make sure you have draft on the walls.
So all vertical walls
or walls that would be close to parallel
to the tooling direction need to have an angle on it.
That angle is going to help the part come out of the tool.
If you don't have that angle in there,
then it's going to bind on.
Other things that you want to control for
are the model thickness.
You may have an engineering requirement
that changes the thickness of the part
or a clearance issue,
so you want to drive these things intelligently.
I'm going to go into Tools, Formula,
and within my formulas,
I have the capability of creating my parameters.
So the first parameter I'm going to generate is an angle,
so I'm going to change this from length
and go all the way up to angle.
I'm going to specify New Parameter of type,
give it a name,
and something like Draft.
Give it a value, say three degrees,
and hit Enter.
I'm going to go in and generate another parameter,
but this time it's going to be length.
Say New Parameter of type,
and this is going to be thickness.
This is two and a half mils.
And I'm going to generate one more.
New Parameter of type,
and this is going to be called Corner Radius.
Oftentimes there's a relationship
between the thickness of the part
and a corner radius.
You're going to see this in injection molded parts.
You may see this in castings.
You may see this also in sheet metal parts.
So creating these kinds of relationships
again makes things much easier
when you have to make modifications later on.
The part thickness has to change.
Then oftentimes the corner radius has to change.
That's why we create these relationships.
So I have my parameter.
Give it a name.
Now the way this is going to work out is I'm going to go in
and add a formula to this.
Go under Renamed parameters.
I'm going to take Thickness,
I'm going to say times two.
And select OK.
Now when I look in my parameter node,
you'll see here there's my draft,
there's my thickness,
and my corner radius.