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Molded Graphite vs RP Graphite Electrode

Ceramic · grade comparison

Molded Graphite and RP Graphite Electrode are both ceramic grades. Molded Graphite is the stronger of the two: tensile strength 15 MPa (2.18 ksi) against 7 MPa (1.02 ksi) for RP Graphite Electrode, about 114% more. RP Graphite Electrode is lighter (1.56 g/cm³ vs 1.72 g/cm³ for Molded Graphite) and RP Graphite Electrode conducts heat better (140 W/m·K vs 115 W/m·K). On the shop floor, RP Graphite Electrode sits in a lower cost tier (standard, $$) than Molded Graphite (premium, $$$).

Molded GraphiteChoose it when strength drives the design.

RP Graphite ElectrodeChoose it when weight is the constraint, or when cost is the deciding factor.

Molded Graphite vs RP Graphite Electrode: properties

Molded GraphiteRP Graphite Electrode

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Shear Modulus

4.2 GPa0.61 Msi
3.8 GPa0.55 Msi

Bulk Modulus

6 GPa0.81 Msi
—

Poisson's Ratio

0.2
0.15

Tensile Strength (Ultimate)

15 MPa2.2 ksi
7 MPa1 ksi

Compressive Strength

55 MPa8 ksi
22 MPa3.2 ksi

Flexural Strength

28 MPa4.1 ksi
11 MPa1.5 ksi

Shear Strength

16 MPa2.3 ksi
6 MPa0.87 ksi

Elongation at Break

—
0.25%

Hardness, Vickers

—
32 HV

Same in both: Elastic (Young's) Modulus 9 GPa1.3 Msi · Fracture Toughness (K_IC) 1 MPa·√m0.91 ksi·√in · Hardness, Mohs 1.5

Physical

Density and transition temperatures.

Density

1.72 g/cm³0.06 lb/in³
1.56 g/cm³0.06 lb/in³

Porosity

16%
25%

Same in both: Melting Point (Solidus) 3,650°C6,602 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

115 W/m·K66.4 BTU/hr·ft·°F
140 W/m·K80.9 BTU/hr·ft·°F

Thermal Expansion (CTE, 20–100 °C)

3.2 µm/m·K1.8 µin/in·°F
2.2 µm/m·K1.2 µin/in·°F

Same in both: Specific Heat Capacity 710 J/kg·K0.17 BTU/lb·°F · Max Service Temperature (continuous) 450°C842 °F · Min Service Temperature -200°C-328 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

9.5×10⁻⁶ Ω·m374 µΩ·in
8×10⁻⁶ Ω·m315 µΩ·in

Volume Resistivity

0 Ω·cm
8×10⁻⁴ Ω·cm

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

85 / 100
65 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

95 / 100
90 / 100

Polishability

35 / 100
25 / 100

Sintering / Firing Temperature

2,800°C5,072 °F
2,900°C5,252 °F

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

130 MJ/kg55,890 BTU/lb
65 MJ/kg27,945 BTU/lb

Embodied Carbon (primary production)

9 kg CO₂/kg
6 kg CO₂/kg

Embodied Water

60 L/kg7.2 gal/lb
25 L/kg3 gal/lb

Same in both: Typical Recycled Content 5%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

9 kN·m/kg
4 kN·m/kg

Specific Stiffness (E / density)

5.2 MN·m/kg
5.8 MN·m/kg

Thermal Diffusivity

94.2 mm²/s
126.4 mm²/s

Thermal Shock Resistance Index

60
49

Strength versus weight

Yield strength against density for every ceramic grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

501002005001,000234567Density (g/cm³)Yield strength (MPa) — log scale

Manufacturing and finishing

CapabilityMolded GraphiteRP Graphite Electrode
Default condition——
Relative cost$$$ Premium$$ Standard
Min. machined wall——
Best machined surface——

Molded Graphite vs RP Graphite Electrode — frequently asked

Is Molded Graphite stronger than RP Graphite Electrode?

Yes. Molded Graphite has a typical tensile strength of 15 MPa (2.18 ksi) against 7 MPa (1.02 ksi) for RP Graphite Electrode — about 114% more.

Which is cheaper, Molded Graphite or RP Graphite Electrode?

RP Graphite Electrode is the lower-cost material: it sits in the standard tier ($$) while Molded Graphite is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.

Which is easier to machine, Molded Graphite or RP Graphite Electrode?

Molded Graphite, by a small margin. Both rate excellent for machinability — 95/100 against 90/100 for RP Graphite Electrode.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Molded Graphite and RP Graphite Electrode side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.