Hello. It´s good to see a community around the "fantastic" world of plastics.

I´ve been dealing with a problem, but i´m all out of ideas. we have various brands of injection molding machines, one of them is a Toshiba with a screw size of 22mm. As soon as the machine got here, it had problems feeding the material (PP). Toshiba sent us a new screw. The problem improved a little, but we still have the problem.

Problem description:

With heavily coloured materials (PP) the screw just won´t feed, it seems as if the material slips around the screw. It also happens with polymer regrind. I´m limited to 20% of regrind, more than that the feeding times are very unstable. I´ve tried grooving the cylinder, and changing the screw with one from another manufacturer. The feeding response improved, but I still have the problem sometimes. The funny thing is, we have another machine (different brand), same screw size, and the feeding reponse is very good. I´ve tried comparing screw designs, but they are the same.

I would like some feedback, if someone has already been through the same!.

I have a video of the problem but i don´t know how to upload it here, if someone has an insight of the problem i could send it by e-mail.

Thank you.