Reg-Injection moulding

What is two stage clamping in injection moulding machine

 

There are machines designed to close within a fraction of a millimeter,
shoot the shot, and then close fully to "coin" the plastic to fully
fill the cavity, and I understand this is often used in molding
polycarbonate lenses, as one example of the technique.

I think I've seen this described on a number of injection machine
specs, but never had a reason to use it myself.

Bo

 

You could indeed say this is a "Hybrid Injection Compression" process.

I believe Arburg has this "coining" option available specifically for
producing optical lenses, as I recall discussing this with the Arburg
guys a couple years ago.

In lenses, you need to get away from miniscule flow lines and
apparently a small amount of coining does the trick, to get better
lenses.

I personally haven't molded these types of parts, though.

Bo

 

Seth,

That was my understanding too - but Bo's description also sounds
possible although I've never seen/heard of it - but then again we've
not done any tooling for lenses yet.


Kev

 

I can't remember what it is called, but it isn't compression molding as I
know it (used for molding rubber parts, where you put a slug of thermoset
material in a mold, then close the mold over it, forcing the material into
the mold shape, with lots of flash and often overflows). I think the process
Bo described was developed for making CDs and DVDs.

That's my understanding as well, but I'm a plastic part designer, not a tool
designer.

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