mold tools

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?

www.dezignstuff.com/a.EPRT

www.dezignstuff.com/b.EPRT

Any general comments on the Mold Tools would be helpful.

Thanks,

Matt

 

I need to add another example...

www.dezignstuff.com/c.EPRT

 

Matt,

It would be helpful if you didn't publish in Edrawings 2007. You're not
going to find many people that can read it


Mark

 

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
opposing cavity.

When alignments get really tight, I use the external PCI or Progressive
Interlocks, or the T-Interlocks with Stripper Plates.

Bo

 

Hmmm. Meant the X-Interlocks.

Bo

 

No one wants to comment on the mold tools?

 

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.)

Jerry Steiger
Tripod Data Systems
"take the garbage out, dear"

 

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.

Regards,

Erik Hinson
Design Engineer
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
the tool!

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.

Jerry Steiger
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
critical.

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
product cost.

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
parts.

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.

Bo

 

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
it.

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
designers.

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
sleeves.

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).

Bo