Using Regrind

[Anuj Kumar]

Dear Members,
Regind mixing can be done upto max.If the MFI measurement is OK .Please suggest.

[rickbatey]

Providing your customer allows regrind:If you have a good machine, treat the melt kindly, and the part can accept the regrind-you will be surprised how much regrind you can run in a part and make the same part you were making before! With the MFI changing (dropping due to the prior melt history of the regrind), the peak injection pressure should drop but everything else should stay pretty much the same. If not, you have an issue with how robust your process is, the press, your mixing method, or you have a higher melt history/shear on the resin than you thought.
I have seen Engel and JSW's run 100% regrind for a few shots, then back to 100% virgin; and only the peak injection pressure drop and cushion change.
The part looked the same!
I always do the extreme when testing. I run 100% regrind and test the parts, then the 75 and 50% mixes. then I can make an informed decision as to what mix we will run.
Hope this helps! Rick.

[Zehrmldr]

Depending on the material, I have ran 100% regrind. Your process will change, and it will take the press some time to settle down, so you will have to keep a close eye on it for a while. PP- flexible PVC- PE- Nylon, I have had success running 100%. Start with slow speeds and pressure on injection, and post injection pressure as well as time. Do not over pack your mould. Increase your pressure and time slowly. To fast or to slow and you will not get a good looking part(happy medium). Not sure what your running but be sure that your regulations allow for high regrind rates. Keep in mind that some materials will not run with 100%
Good Luck. I hope this will help