I'm looking for input on the SolidWorks mold tools. Does anyone have any
opinions they would like to share?
Also, how frequently do you make use of interlocks on molds? What is the
typical interlock angle that you use?
In the edrawings at the following link, which scenario is best for molding?
Any general comments on the Mold Tools would be helpful.
If I had to make the tool, I think I'ld prefer to make "c.EPRT", or if
there were some reason why another part made it desirable to have the
edge of the cavity on the parting line, I'ld pick "b.EPRT".
I did a part with a semi-circular parting line like this a year ago,
but I didn't worry about the angle, & your arc angle looks to be about
90 degrees which is not going to be a problem in self-aligning with the
When alignments get really tight, I use the external PCI or Progressive
Interlocks, or the T-Interlocks with Stripper Plates.
Draft analysis,parting line and shut off surfaces routines are generally
useful. For the shut off surfaces to work, one needs to learn when to
designate a loop as `no fill' and then create surface(s) manually to deal
with what's there. I have found it valuable to be able to generate a knit
surface for the core and cavity this way.
Major problem is that the parting surfaces that SW automatically generates
is almost always completely useless-if not downright laughable. Furthermore,
although it's possible to use the (vastly improved) SW surfacing tools to
manually create what amounts to a parting surface, I have not found a way to
jump back into the SW mold tools to have it create the core and cavity
inserts once I have bypassed their parting surface creation step. No problem
for me since I always go into assembly mode and use the knit surfaces I
created with the shut off surfaces to proceed with core/cavity creation that
In summary, the failure of the parting surface feature seems to
short-circuit any attempt to fully utilize the mold tools as SW intended.
I don't use them much, being a part designer instead of a tool designer.
Every once in a while when I design a part that seems to be tricky to mold,
I will go through the exercise of generating a core and cavity. My vague
memory is that JK got it right in his description. (And Bo made the same
choices I would make on your abc question.)
Tripod Data Systems
"take the garbage out, dear"
"Jerry Steiger" wrote in message > Every once in a while when I design a
part that seems to be tricky to mold,
Jerry-you're my hero. I can't imagine any of the people I work with
analyzing their product designs with molding in mind. They always seem to
resent the fact that I point out problems to them.
If you ever need any mold design help-please don't hesitate to contact me.
Jerry- Mold tools are helpful when applied to non planar parting lines
IE: a part shaped like a mouse. I have experimented with the tools,
and found I have much more control & time savings just locating the
part in the mold, and creating each half of steel manually, then using
the cavity command. This method is very quick and easy to change. It's
great that you are looking into how the part is going to be laminated,
i commend you for it.
Prestige Mold Inc.
Doesn't do me any good to design a whiz-bang part if it can't be molded!
Doesn't help me out if the mold costs too much or it takes too long to build
We usually have our tool designs done by the mold maker or their favorite
tool designer, so we're not directly involved in the selection.
Tripod Data Systems
"take the garbage out, dear"
Jerry, your note is exactly why the part designer NEEDS to plan the
tool as he designs the part.
Some things are routine, and you don't have to think about them, UNTIL
your new design starts pushing the limits of things is when it turns
Limits can be stress, thin or thick walls, bonding, ejection, warpage,
gating or making sure a complex part stays on the ejection side (all
the time), and lots of other things.
In my case, undercuts of all types can dramatically reduce assembly
times and parts and inspection while increasing quality, if done right.
Some calculations, material analysis, ejection planning, Mold Flow
analysis and hard thinking about the WHOLE process from molding, to
ejection, to assembly and even packaging and shipping are a part of the
I've found that many toolmakers will attempt to default to the easiest
way for them to do something, as opposed to how I know I must have it
done to work best, for a particular new design purpose. Hence, though
I don't do the mold design, still I do the cavity layout so I can talk
real issues with the solid models with the designer-tool maker. This
has kept everyone on track with fewer wasted hours and remade tool
The most recent "stretch" I did in ejecting severe undercuts worked to
a tee, though there were a couple minor areas needing adjustment to
handle deformation during ejection, which I missed.
The payoff, in the end for me was no gluing or ultrasonic bonding with
great cost reduction.
Jerry Steiger wrote:
If I were a mold designer I would disagree strongly with that. As John
K points out, he gets a parts where part designers can't even design a
plastic part that can be manufactured much less design a mold to make
I never dictate to the mold builder how the mold should be made. That's
his gig, and he usually has a few things that I hadn't considered. I
make the part so its manufacturable and let him decide how to do it.
Sometimes I leave areas indeterminate knowing that the mold builder has
options. Locking him into one solution when there are several possible.
Plus, if every part designer were a mold designer, who would need mold
The best process I ever worked with had tooling engineers right beside
the part modelers. Everyone got involved from the begining. Not every
company has that luxury, but it makes for better parts, better molds
and far less redesign.
Perhaps I should have said that you have to plan the specific special
details (if any) that are essential to part function.
When I need a seal surface, I can't have a parting line, bubbles or
knit line on it. When I need undercuts, I need to understand how I am
going to strip the part, or release the undercut. When I need options
in the part for various product models, I have to plan those options
generally without hopefully just replacing a couple core pins and
Some of these things are simple, but save me from producing a whole
additional mold. The mold maker & his designer sometimes don't look @
options that reduce the number of tools (like when I'm trying to save
funds on a startup deal).
snipped-for-privacy@veriz> > Jerry, your note is exactly why the part designer NEEDS to plan the