Compensating for Barrel Residence Time…

I got this question regarding a situation many small-part molders find themselves in…

Our Maintenance crew came up with the idea of putting E-Dart systems on our presses. Some of our presses are running with less than 20% barrel capacity. What do you think about this plan without any change in the barrel capacity.
My Response
Regarding eDart Technology… Let me explain a few points for my readers.  In my experience, such technology is best implemented for one of two reasons… 1) to detect and isolate specific part defects such as short shots. 2) to accurately control the transfer from 2nd stage pack to 3rd stage hold using cavity pressure measurements. In both these situations, the mold must be properly instrumented with pressure sensing technology… and your employees need to be trained on the use of such technology before implementation. The learning curve for this technology is steep… so be sure that all your employees have a firm grasp on the fundamentals first.
Regarding Your Question… Based on your line of questioning, my assumption is that you are asking if the eDart will help compensate for the complications arising from running less than 20% machine capacity. A machine running below 20% capacity typically has a residence time of 10 cycles or more. For this reason, the inherent complications resulting from a long residence time such as degradation, property loss, and presence of volatiles will not be affected.
If these were my machines, I would invest in new screws and barrels for the machines before I bought anything else. My approach to technology is as follows… Don’t purchase the latest and greatest until you are 100% sure that 1) your employees are getting the most out of the your equipment, and 2) it will make a significant difference.
With your improperly sized screw and barrel… It is like putting a turbo charger on a car which has a flat tire.
Additional Thoughts
For more information on proper barrel sizing, please read the following entry:
  1. MJ left a comment on 2009/11/10 at 4:48 pm

    Hello Arturo.
    If you want to do machine evaluation with E-dart, then you need to put sensors in mold where your machine and use 20-80% stroke capacity. When you want to do speed linearity test, you need to give your machine good distance to reach fill speed.

  2. Andy Routsis left a comment on 2009/11/11 at 9:45 am

    Thanks Milan,
    Putting advanced technology on an improperly configured machine is like putting a really bad mold into a brand new machine.

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