Looking for some better cavity/core tutorials

I'm trying to get a mold maker up to speed with SolidWorks and using my
part designs to create molds, and I'm not even yet up to speed on the
new mold tool functionality of 2005. Anyone out there know of some
better resources to get ramped up quickly? The Help files are (as
usual) somewhat limited in their usefulness . . . especially for us
non-toolmakers. And although the mold maker I'm dealing with knows his
mold making well enough, he's old-school. Not totally boneheaded with
computers, but close. (Yes I know, it's better to deal with someone not
so old-school as to be so very behind the times, but there's little
choice at this point.). Hey John K and Mark M . . . help!!

Thanks,
Mark 'Sporky' Stapleton
Watermark Design, LLC
www.h2omarkdesign.com

 

I'm not jk or mm, but I might be able to tell you what you need to know
about the SW mold tools.

If you are doing anything more complex than a trivial box, SW mold tools
are likely to choke. In fact, if the PL has any section where it is
concave at all, the mold tools are almost guaranteed to not get you
where you need to go. By "concave", I mean if the projected outline of
the PL onto the parting plane is like a "C" instead of like an "O", then
forget it. The weakest links of the SW mold tools in my experience have
been the Parting Line, Shut Offs and Parting Surface functions.

In fact, the Tooling Split function is going to give you multi bodies
instead of separate parts in an assembly. Feed that to your CAM
program.

I won't bother plugging the mold software I like, cuz your old school
fella isn't gonna like it, but in general, here's an outline for how the
mold splitting stuff works:

1) Draft analysis. Figure out what faces are on which side of the PL,
and if any faces straddle it or form undercuts (undercut would be a
single blue face (core direction)in a sea of red faces (cavity
direction)).

2) Split any straddles and put them to the correct side, fix undercuts

3) Collect faces of any side pulls. This is actually something that
the SW tools are really good at - in SW05 there is a new "Core" function
(extremely unfortunate name) which allows you to just make a sketch and
extract a core.

4) Build the parting faces. This is typically the hard part. For
simple PLs, it can be done using a Radiate or Ruled surface from the PL,
but in more complex PLs, it's not a single step, you might have to use
planar, or extruded surfaces, lofted surfaces, etc.

5) Close any windows or shut offs. A hole through the part needs to
have a surface placed where the steel from one side of the mold will
touch the steel from the other side of the mold

6) Passing shut offs are a manual modeling exercize regardless of what
software you use (as far as I know).

7) Knit the parting surface together with all of the faces on one side
of the mold together with the shutoffs and passing shutoffs. This
basically creates the functional end of one side of the mold insert.

8) Extrude up to the surface you just knit together. This should be
done in an assembly. Don't make a multibody part. This is just an
opinion, but there are a lot of reasons behind the opinion.

9) Extrude the other side up to the same surface, and subtract the
original plastic part from it with an incontext cavity feature.

10) If you followed that much, you can figure out how to do any side
pulls, cores, actions, lifters, etc.



Anyway, that's the method (plus or minus) used by Splitworks or
Faceworks or even Imold, I think. You can also do it manually. To do
that it's easiest if you use a face selection filter and window select
while looking straight down at the PL.

Anyway, good luck.


matt

 

Thanks for your replies, both Matt and John. I understand enough to see
that it's as clear as mud and that's just the way it be. No fault to
you. I appreciate what you wrote, though, and I'll see how much of it I
can make sense out of.

Best regards,
'Sporky'

 

Don't be discouraged. To me, learning how to do mold design was the
toughest work I've ever done in SW. I had to work with some people who
knew what they were doing in order to get the hang of it. It may not come
to you overnight. Knowing how to do the modeling is one thing, then there
is knowing all the details of how the mold works, where to put the cooling,
what type of cooling, different types of mechanisms, and all of the
engineering details that make it almost as much machine design as anything.
I can't do the second part, and my hat's off to those who can.

Anyway, good luck.

matt

 

jk,

I will try to explain one way. It is not very "straight forward" but:
1. In the Solid Body folder, right click one of the bodies and select
"Insert into new part". A new part will be created with this body only
making up the entire part.
2. Repeat for all bodies.
3. Insert ALL of the newly created parts into a new assembly dropping each
one of them onto the origin.
4. You now have a sub-assembly of the molding inserts that you can use to
drop into a moldbase. Changes WILL propagate to these new parts that were
made from the bodies.

Hope this helps.

 

Even easier than that is to use the Split (Insert, Features, Split)
command which takes the bodies, saves them all to individual parts, and
assembles them back into an assembly.

My point is that an assembly is what SW should create as a product of
their mold tools by default because most CAM systems can deal with
individual parts better than multibody parts. Beyond that, to create
drawings from a multibody part requires doing a dance with
configurations. Plus, just from a data organization standpoint, with
the multibody approach you're putting all of your tooling and plastic
part design data into a single file.

 

True! I agree with everything you say...
That's one of the reasons why I don't use these tools. I just use SW with
no add-ons. I have developed my own methods and techniques that would take
a small novel to describe, but is very robust. It might not be the most
efficient way, but like you say, from a data organization standpoint it
makes sense (at least to me anyway).

 

Thanks to all three of you for attempting to educate me. I've found a
way that works for what I need right now, and I'll go back over all of
these other ideas later. Using the info you all supplied may help
someone else as well.

Best regards,
Mark 'Sporky' Stapleton
Watermark Design, LLC
Charlotte, NC
www.h2omarkdesign.com

 

Hello and thanks to everyone that contributed to this thread. It has
been quite helpful AND I am still waiting for a concise, thorough book
or tutorial to help me with this topic of mold building. I do some very
simple molds for plastic, but mostly design and manufacture patterns for
metal castings.

Thanks again,
Jerry Forcier

 

Matt-

I've reluctantly given up on split parts and gone back to the base part
method because while they seem the ideal solution to a number of toolmaking
problems, the problems they create can be show stoppers.

I've spent hours trying to pin down how my problems occur in simplified
assemblies (i.e. emailable) with no luck, and just gave up on the whole
business a few months ago. The problems seem to center around parts with a
complicated base part feature and multiple configurations. If the part
containing the base part contains a split feature and is opened without the
base part being open as well, all the features below the base part feature
fail with a message something like "no body to act on".

That's only one problem. Additionally, split part features take a really
long time to regenerate and seem like one of those swx features that can get
set to always rebuild.

Also, there's something buggy when the feature that creates the split (the
sketch or surface body) changes, then the split bodies references get lost.
My sense is that this one may be improving with the newer sp's.

It's really a shame, because the concept is so promising and in theory a big
time saver, not so much for the initial tool splitting, but for the more
everyday stuff like sub inserts and corepins.

-Jason S.