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View Full Version : Something I've done in the past and started doing again...



pjhall
20th September 2013, 04:19 AM
Suhas,

I was reading your latest news letter and thought I'd share something I started doing again regarding 95% fill (you previous topic on charge delay).

Back in the late '90's I was with an automotive molder in Clinton, MA. We molded many different configurations of Nylon (Minlon 40% mineral filled) "doors" for HVAC for automotive. These doors were then over molded with santoprene all along the outer edge. They had a cylindrical hub with a rectangular ribbed section coming off it with anchors holes for the over mold. Anyway, they would warp like boomerangs if over packed. I decided to put a picture of what the part should look like with pack/holding pressure @ 0 along with the weight on the molding set-up sheet. The final part weight was also on there. If there was an issue or just as PM we would check what the part looked like with pack/hold @0. If it did not look like the picture then the hot runner would need to be opened up and "decapped" to remove the mineral build up or there was some other problem. This really helped because we ran the molds in various tonnage / barrel size presses.

Fast forward more than a few years...I started doing this again and man does it help. Its especially helpful with glass or other filled materials in hot runner molds. But make sure the hot runner is designed so that you can take the bolts out of the cavity plate, close the mold, strap the cavity plate to the core plate, and open the mold to expose the hot runner tips.

Just a tip not a question,

P.J.

Suhas
20th September 2013, 05:00 PM
Hi PJ,
That is a fantastic idea. I have been doing this also and is one of my slides in my seminars. A picture and part weight at transfer - excellent. This also helps out in batch to batch variations. In fact, I have been thinking of advocating the 'removal of a transfer position' from the process sheet. It would be 'match the transfer position to achieve a part weight of 4.67 grams' - What do you think?
Brent, Rick, are you there?
Regards,
Suhas