Silver Graphite

Materials

Type

Fine

Medium

Large

Graphite content in %

3 – 4 – 5

3 – 4

3

Grain size

1 to 5 μm

5 – 40 μm

20 – 160 μm

Metalor' designation

F

M

G

N.B. : in certain cases, a TGG (extra coarse) grain size might be needed, available on demand

Manufacturing processes

Technique

EXTRUSION

DIE COMPACTING

C – Grain alignment*

PERPENDICULAR

PARALLEL

RANDOM

Metalor's designation

ET

ED

U

Contact surface

10 to 200 mm²

10 to 400 mm²

no limit

Contact thickness

0.35 ≤ h

0.40 ≤ h ≤ 1.5

0.50 ≤ h ≤ 2.5

Available forms

Tip – Wire

Tip – Profile

Tip

N.B. : in certain cases, tips obtained through die compacting are pressed a second time
* In relation to the contact surface

Physical characteristics

Grain size

Fine

Medium

Large

Graphite content in %

3

4

5

3

4

3

Theorical density g/cm³

9.46

9.16

8.88

9.46

9.16

9.16

IACS conductibility
Measured by eddy
Current method %

ET

78

64

59

83.5

75.5

82.5

ED

88

80.5

78

87

81

90.5

U

67

57

49.5

82

76

81.5

HV hardness

ET

45 to 55

40 to 50

40 to 50

30 to 40

30 to 40

30 to 40

ED

35 to 45

35 to 50

25 to 35

33 to 40

30 to 40

30 to 40

U

30 to 40

30 to 40

25 to 35

25 to 35

25 to 35

25 to 35

Underlayer characteristics

Silver face

1 FACE

2 FACES

0 FACE

Underlayer thickness e

10 to 150 μm

0

Underlayer with solder plating

yes

yes

no

Other characteristics :

  • The underlayer in the case of random structure my be fine silver, or there may be no underlayer at all.
  • Solder material : any type which is adapted to the assembly
  • Identification of the solderable face through marking to be defined in cooperation with the customer

Designation

Metalor's wide range of material necessitates an accurate description : structure, number of silver faces, grain size, graphite content.

  • FET 1-5 : Tip with fine grain, perpendicular structure, 1 silver face, 5 % graphite
  • MED1-3 : Tip with medium grain, parallel structure, 1 silver face, 3 % graphite

Electrical characteristics

Because of its properties, AgC is the ideal material for protection switchgears : high breaking capacity, low resistivity.
The properties of AgC depend upon the amount of graphite added, the manufacturing process and grain size.

Example, as a rough estimate, for a 5 000 A breaking test :

Graphite content in %

3

4

5

Erosion (mg)

FET

31

45

62

FED

100

122

143

Applications

Switchgears

  • Any protection swichgear requiring breaking capacity at 16 to 1 000 A rated current :
    • Circuit Breaker for home
    • Residual Current Circuit Breaker for home
    • Industrial Circuit Breaker for industry
    • Contactor Breaker for industry
  • Any switchgear utilizing sliding contacts
  • Any contactor incuring risks of micro-welding