DEF PROSPETTO spazzole - Timcal Graphite

Powder
Properties:
Springback
Measuring method
The springback is a reading giving the resilience of
compacted graphite powder. A defined amount of dry
powder is poured into a die. After inserting the punch
and sealing the die, air is evacuated from the powder.
Pressure is applied (p=0.477 t/cm 2 ) and the powder sample
thickness is measured. Thickness is measured again
after pressure has been released.
Conclusion
Springback and compact density of graphite powders
are physically connected parameters, which give
information about the compactibility of powders and
dimensional stability of compacts in any pressing
direction. Springback is influenced by pressure, particle
size, crystalline structure ad other properties.
Crystalline structure is the main parameter.
A high crystalline structure results in low springback.
Compacts produced from powders having a low
springback can be easily formed and pressed with
greater accuracy.
Punch
Seal
Die
Compact
Vacuum line
Pressure
Pressure meter
H(p)
H(0)
Spring back
Metering
element
www.timcal.com
Springback (%) Springback (%)
25
20
15
10
5
GB
KS
0
0 20 40 60 80
Particle size d90 (µm)
25
20
15
10
5
Springback of graphite compacts
Die diameter: 20 mm
Pressure: 0.477 t/cm 2
100 120 140 160
0
0
Pressure (t/cm
0.2 0.4 0.6 0.8
2 )
H (0) - H (p)
SB = x 100 %
H (0)
SFG
T
T 44
KS 44
SFG 44
1