I just got this question the other day...
MJ
When I want to move mold to another machine, which machine parameters should I check?
My Response
This question brings up the importance of machine independent documentation that includes part specific data such as part weight, fill time, coolant and melt tempertaures as well as the actual pressures applied to the polymer.
When you do this, you can ensure the actual process output from two different machines match. The most important factor is not the parameters that go into the machine, but the parts and associated outputs that result from the process.
Additional Thoughts
This topic is also addressed in the following blog: The Symptoms Of Machine Dependent Documentation
-Andy
Andy,
I have tried move mold from machine to different machine today. I took samples without hold pressure and with hold pressure. I tried the replicate process on different machine. I adjusted the same fill time and all needs parameter like were on machine before, but parts were more short like before and also they were havier like parts before. I don't understand.
Milan
Hello Milan,
Could you please clarify...
Which parameters correspond... which parameters differ (such as short on machine A is heavier, etc.)
-Andy
Andy,
For clarifing:
Yesterday I tried to run one mold on machine B, and I adjust all injection parameters
according parameters from machine A. Firts I scaled my parts from machine A which were taken without hold pressure. They were full 98%. But, when I scaled parts here from machine B, when they were less full 80%(short) they were
a havier than parts from machine A.
How this could happened? Could I have a problem with melt density or melt temperature?
I heard, when barrel temperature is higher 20°C that volume of material could expand 1%, and this cause that molecules are to far from each other. I didn't get melt temperature directly from melted material (from machine A), but temperatures should not be 20°C higher, because I adjusted same barrel tempertures. Srew diameter on both machine is same 25mm. Barrel volume: machineA is58,3ccm, machineB is61,3ccm.
Milan
Milan,
My first thought is that there was something wrong with the weight. Check some aspects... is the same scale being used for both parts... is there a runner or gate partially attached... is the same lot of material being used... are the nozzles the same diameter... if you have the shorts from machine A, measure them on the same scale as the machine B parts. Such a variance leads me to believe that there is something significantly different between the two systems, or the method of measurement.
-Andy
Andy,
I used same scale for both machines. I measured just parts without runners. What I can't say, if diameter of nozzle was same. Could nozzle be a root cause?
Milan
Milan,
The nozzle diameter could make a significant change in both shear and melt temperature during injection. There is a significant change between the two systems, the goal is to identify what is different between the two machines and then correct or compensate.
-Andy