please explain about absolute ram profile. how can i create this profile for new component development. suppose i have this profile from customer, based on this ram profile how can i select a injection machine.
Absolute profiles are used when key machine parameters are known, such as screw diameter and maximum injection rate. Screw diameter needed to get flow rate right.
So using absolute profiles you need data of injection molding machine.
Settings in the injection molding machine properties.
You can get to this dialog by selecting Analysis > Process Settings Wizard,
select Advanced options, edit the Injection Molding Machine,
select the Injection Unit tab, then enter the Screw diameter.
When using absolute ram profile, one also have to choose how this profile is set, meaning
specify the two variables by which the ram speed profile is controlled such as:
- Ram speed vs Ram position
- Flow rate vs Ram position
- and more...
To reach to a reasonable profile, I would prefer to start as per below for "Ram Speed vs Ram position"
- First calculate the shot weight
- based on the known density of the polymer, you will reach to volume required in the barrel
- Once you have the data of the molding machine, that is screw dia, so you have the area
- Now, volume = area x distance(length), so, volume / area = distance, meaning you have the screw position. Take this as a starting ram position + cushion
Regarding the speed, one should decide the speed such that the viscosity of the molten polymer should be uniform for the better filling of the cavity.
To arrive to the uniform viscosity, one can run the different iteration and calculate the viscosity = peak pressure x fill time for different iterations, than plot the graph of viscosity as function of speed. look for the speed which can have uniform viscosity. Based on the speed arrived run the analysis with "Ram speed vs ram position"
I am interest with your answer in order to find the ram speed. Did you refer any journals or books for your justification on that particular solution?Because I need the references on that.