gefran SENSORMATE QE2008-W SET User Manual page 38

4�1�3�1� Measurement prerequisites
The Cavity Pressure Profile measurement using the QE2008-W is an indirect measurement of the pressure on the
press' Tie Bars. The basic physics concept that lies behind the measurement is that a pressure (P), when applied to a
surface (A), generates a force (F). In case of injection molding machines, these parameters are the holding pressure
and the cavity area projected on the mold.
It is immediate to see that, the bigger is the holding pressure and the bigger is the produced part, the higher is the
force being generated.
For an indirect measurement of the cavity pressure profile, it is mandatory that this force is high enough to generate a
sensible elongation of the tie bars.
Directly related to the tie bars elongation is the clamping force set value, which has to be chosen carefully: it is
important that the clamping force is not too high (S1) in order to avoid over stressing the mold and the tie bars as well
as to prevent venting problems and energy consumption excesses. On the other side, it is also important that the
clamping force is not too low (S3), so mold separation and consequent part flashing can be avoided during the injec-
tion phase. The proper range stands between S1 and S2, therefore with slight mold separation (ref
The following equation can help understand if the machine setup is correct, and if the cavity pressure profile will be
measurable on the tie bars using the QE2008-W. Obtaing a value bigger then 10 mictrostrains will lead to a proba-
ble successful set of measurements.
where:
- P : holding pressure in "bar"
H
- A: projected surface of the produced part in "cm
- F : clamping force in "kN"
C
- D: diameter of the Tie Bar in "mm"
- E: Young's modulus in "GPa"
38 / 56
2 "
Subject to technical modifications
[1])�