Re: More.....RPM

John Hagen <sprinthag@...>

Thanks Dennis for clarifying that.

If I were to take the time to really think about it, I knew all those
methods and there proper names but it sure is nice to see it spelled out.

However, doubtless, most, including myself, will continue to use die casting
to denote molded metal and molded or just plain plastic for injection molded
plastic items. It's just easier and more universally understood among the
majority, in particular those younger than me (which is a very large group).

I remember a discussion about case hardened tools that occurred back around
1965 between my father and one of my friends who was just about finished
with his tool and die apprenticeship. The problem was they were both talking
different eras with dad's experience going back to WWII and beyond. Back
then case hardening was used in applications that were no longer used twenty
plus years later.

John Hagen

From: STMFC@... [mailto:STMFC@...] On Behalf Of
Sent: Tuesday, May 15, 2012 3:01 PM
To: STMFC@...
Subject: [STMFC] Re: More.....RPM

--- In STMFC@... <> , "derrell"
<onagerla@...> wrote:

So we continue to have to use parts cast from dies that are decades old
and warp to fit!
As long as we are discussing this, we need to clean up some terminology...
the discussion tends to sound like those TV newscasts where anythin that
runs on rails, caboose, locomotive, single stationary car, entire consist
displaying markers, is a "train" :-(

DIES are cutting or forming tools that work solid material... think punch
press work. Die-cut shingles are made with a DIE.

Early in the history of injection molding either plastic or metal, the
craftsmen that made dies, die makers, were the people with the skill set to
make the molds, so the became tool & die makers. This led to the early metal
process being called die casting, because it looked like the metal was being
poured into a stamping die, but it's not the proper terminology. The usage
lingers on with the accepted term "die cast", but the tool is properly
called a mold.

The tool into which a liquid or plastic is going to be molded is properly
called a MOLD.

CASTING is the process of filling a mold with only gravity for assist. Resin
kits are usually CAST.

MOLDING is the process of injecting the material under pressure.
Themo-plastic parts are MOLDED, not cast.

The current term for die casting is METAL INJECTION MOLDING, but the old
term has yet to completely die out.

Dennis (picky, picky, picky) Storzek

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