Editors Note: Sorry about the news digest not being posted last week. I had a bit of a family emergency.
A moisture analyzer is a great tool for any plastic processor to have. It will tell you for sure that you are drying the material adequately. It is also a great tool for material suppliers to have so that they can aid customers who are trying to troubleshoot problems.
How exactly a moisture analyzer works seems like a bit of witchcraft. You put a bit of material in, you choose some type of program and hit the start button. Ten to twenty minutes later, the readout shows a percentage. The process is a little bit more complex than just heating the material and burning off the moisture weighing the sample before and after. You don’t need a moisture analyzer to do that, you can do that with a lab dryer and lab balance. How does it work?
Hydraulic Pressure vs Plastic Pressure
When we refer to injection pressure, we can be talking about one of two things. We can be talking about hydraulic pressure which refers to the pressure that the hydraulic ram is exerting on the screw or we can be talking about plastic pressure which is the pressure that the screw puts on the melted plastic.
These two are not the same thing and if you specify an injection pressure range on your processing guides, you should only specify hydraulic pressure and you should be very clear about it.