ballanced runners
ballanced runners
(OP)
I have an 8 cavity plastic injection mold with hot manifold into cold runner.
The outside cavities short shot about 25% less of the inner cavities. What is the best way to balance the outside cavities for uniform mold fill?
The outside cavities short shot about 25% less of the inner cavities. What is the best way to balance the outside cavities for uniform mold fill?






RE: ballanced runners
RE: ballanced runners
this is a 3 plate mold 8 cavity "H" style runner on both sides of cender line of mold. the outside parts are short shot when backing off mold pressure.
RE: ballanced runners
RE: ballanced runners
To balance non-symetrical runner systems, see our website http://www.polytechconsultants.com/balancing.htm
Regards,
Peter P
RE: ballanced runners
http://www.immnet.com/articlelibrary/archive/getOneArticle.php3?getArtID=1664
It's in the IMM Injection molding magazine
RE: ballanced runners
The easiest thing to do is probably to get a pin grinder and open the runners (and/or gates) to the slow-fill cavities during the short shot process until all cavities are filling equally. Not very scientific, I know, but effective and simple.
Good luck
RE: ballanced runners
RE: ballanced runners
After a small land, vents should be very large so that accumulation of flash, mould deposite etc does not block them.
Another posibility is eneven mould cooling or heating. Do some runners go close to water passages or mould cavities while others do not.
Before you get out your die grinder, do a lot of shorts to various degrees, so you see where the imballance starts. Obviously, take care not to stick the shorts in the mould if at all possible.
Regards
pat
RE: ballanced runners
RE: ballanced runners
Measuring surface temperatures after the mould has been running for a while, and takeing progressive short shots tells us a lot.
I guess the melt flipper is more effective on materials that respond well to a lot to shear, like PP for instance, but not so effective on the likes of nylons. I am certainly interested to find some data regards this
I guess to check if it might be a canditate for melt flip, try very fast injection speed with cold material, then very slow with hot material. I am also interested to know if this test works as an indicator
Regards
pat
RE: ballanced runners
Please visit the site and send me an email if you have any specific questions. The technology is guaranteed to work on any material as well. Take care and have fun molding!!
Dave