MG Carbon Brush MG-SnPb
Additive grade
MG-SnPb = copper graphite with tin/lead lubricating additions
Specify tin/lead lubricating additions when high surface speeds or dry, high-altitude air demand extra lubrication and lower ring loss; lead-bearing versions are largely replaced under RoHS.
Values for the MG-SnPb condition
Other MG Carbon Brush tempers and conditions
MG Carbon Brush is listed in 5 conditions; see the grade overview at MG Carbon Brush.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
MG-SnPbThis page Copper graphite with tin/lead lubricating additions | Specify tin/lead lubricating additions when high surface speeds or dry, high-altitude air demand extra lubrication and lower ring loss; lead-bearing versions are largely replaced under RoHS. | — | 17 | 0.5 | 10 HV | 100 W/m·K |
MG-MCDefault Medium-copper metal graphite | Default general-purpose ~55–75 % Cu metal-graphite grade: use for low-voltage, high-current DC motors, starters and traction motors where resistivity and wear resistance must be balanced. | — | — | — | 12 HV | 110 W/m·K |
Low-copper metal graphite | Pick for 24–110 V DC motors with demanding commutation, where the higher contact voltage drop of the 30–50 % copper content suppresses ring fire; conductivity is lower than richer copper grades. | — | — | — | 15 HV | 55 W/m·K |
Silver-graphite brush / contact grade | Use the silver-graphite grade for instruments, servo tachogenerators, fractional-horsepower motors and signal slip rings needing very low, oxidation-free contact drop; it is the costliest option. | — | — | — | 18 HV | 190 W/m·K |
High-copper metal graphite | Choose ~80–90 % copper content for plating and electrolysis rectifier sets, slip rings and ultra-low-voltage, very high current duty where minimum contact drop matters; wear life is shorter. | — | — | — | 20 HV | 200 W/m·K |
What is MG Carbon Brush MG-SnPb?
MG Carbon Brush MG-SnPb is MG Carbon Brush in the MG-SnPb grade — specify tin/lead lubricating additions when high surface speeds or dry, high-altitude air demand extra lubrication and lower ring loss; lead-bearing versions are largely replaced under RoHS. MG Carbon Brush MG-SnPb has a tensile strength of 17 MPa (2.47 ksi), weaker than 88% of ceramic grades. The elastic modulus is 11 GPa (1.6 Msi). MG Carbon Brush MG-SnPb has a density of 3.9 g/cm³ (0.141 lb/in³), lighter than 58% of ceramic grades. It melts at 1,083°C (1,981 °F). MG-MC is the default condition FabDigit quotes; MG-SnPb is available on request or by drawing note.
Advantages
- Easy to machine — 88/100, better than 92% of ceramic grades
- Conducts heat well — 100 W/m·K (57.8 BTU/hr·ft·°F), better than 83% of ceramic grades
- Low embodied carbon — 4.5 kg CO₂/kg, better than 78% of ceramic grades
Limitations
- Hard to polish — 35/100, worse than 93% of ceramic grades
- Low stiffness — 11 GPa (1.6 Msi), worse than 91% of ceramic grades
- Needs corrosion protection — 45/100, worse than 90% of ceramic grades
- Limited service temperature — 170°C (338 °F), worse than 87% of ceramic grades
MG Carbon Brush MG-SnPb properties
Typical room-temperature values for MG Carbon Brush MG-SnPb; 15 are specific to this condition. Other listed values are MG Carbon Brush reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
MG Carbon Brush MG-SnPb has a density of 3.9 g/cm³ (0.141 lb/in³), lighter than 58% of ceramic grades. It melts at 1,083°C (1,981 °F).
Mechanical8
MG Carbon Brush MG-SnPb has a tensile strength of 17 MPa (2.47 ksi), weaker than 88% of ceramic grades. The elastic modulus is 11 GPa (1.6 Msi).
Thermal5
MG Carbon Brush MG-SnPb is rated for continuous service to 170°C (338 °F). It conducts heat at 100 W/m·K (57.8 BTU/hr·ft·°F), better than 83% of ceramic grades. Thermal expansion is 10 µm/m·K (5.56 µin/in·°F).
Electrical2
MG Carbon Brush MG-SnPb has an electrical resistivity of 6×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (45/100), worse than 90% of ceramic grades.
Sustainability4
Producing a kilogram of MG Carbon Brush MG-SnPb takes about 55 MJ of energy and emits 4.5 kg of CO₂ — less than 78% of ceramic grades. Typical recycled content is 25%.
Manufacturability3
MG Carbon Brush MG-SnPb's machinability is excellent (88/100, better than 92% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MG Carbon Brush MG-SnPb
Is MG Carbon Brush easy to machine?
Cut dry with carbide or PCD tooling at high speed and low feed; explosion-protected dust extraction is required because the copper-bearing dust is electrically conductive and can short electrical equipment.
Can MG Carbon Brush be welded?
Not weldable; lead wires are fixed to the brush body by copper-tamped riveting or cast-in connections, or by ultrasonic crimping.
Can MG Carbon Brush be formed, bent or molded?
Powder-metallurgy route: copper and graphite powders are blended, die pressed at 100–400 MPa, sintered at 700–1000 °C in a reducing or inert atmosphere, re-pressed for sizing, then machined and chamfered.
What surface finishes work on MG Carbon Brush?
End and curved faces are ground to the commutator radius (arc fitting); impregnation or copper plating may be applied to lower contact resistance. No painting is used.
MG Carbon Brush chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cuelectrolytic Cu powder; to 90% in high-Cu; Ag-graphite uses Ag | 30 – 90 | 68 |
| Snadded in some grades to improve lubrication and sintering | 0 – 5 | 0 |
| Pbtraditional self-lubricating grades; absent in RoHS grades | 0 – 8 | 0 |
| C (graphite)natural flake or synthetic graphite; minor pitch/resin residual carbon | balance | — |
MG Carbon Brush MG-SnPb — frequently asked
What is MG Carbon Brush MG-SnPb used for?
MG Carbon Brush MG-SnPb is typically used for automotive starter motors, low-voltage DC motors and slip rings for high-current transfer. In short: lowest-resistance brush grade; for low-voltage high current; 200 °C service ceiling.
What is the tensile strength of MG Carbon Brush MG-SnPb?
MG Carbon Brush MG-SnPb has a typical tensile strength of 17 MPa (2.47 ksi) — weaker than 88% of ceramic grades. Strength varies by condition: see the 5 listed tempers.
Is MG Carbon Brush MG-SnPb easy to machine?
Yes — machinability is rated excellent (88/100, better than 92% of ceramic grades). Cut dry with carbide or PCD tooling at high speed and low feed; explosion-protected dust extraction is required because the copper-bearing dust is electrically conductive and can short electrical equipment.
Can MG Carbon Brush MG-SnPb be welded?
Not weldable; lead wires are fixed to the brush body by copper-tamped riveting or cast-in connections, or by ultrasonic crimping.
What surface finishes work on MG Carbon Brush MG-SnPb?
End and curved faces are ground to the commutator radius (arc fitting); impregnation or copper plating may be applied to lower contact resistance. No painting is used.
Can MG Carbon Brush MG-SnPb be formed, bent or molded?
Powder-metallurgy route: copper and graphite powders are blended, die pressed at 100–400 MPa, sintered at 700–1000 °C in a reducing or inert atmosphere, re-pressed for sizing, then machined and chamfered.
What is the maximum service temperature of MG Carbon Brush MG-SnPb?
MG Carbon Brush MG-SnPb is rated for continuous use to about 170°C (338 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- JIS C 2802 Carbon brushes for electrical machines — JSA (2016)
- GB/T 1416 (Carbon brushes) — SAC (2019)
- IEC 60136 Dimensions of brushes and brush-holders for electrical machinery — IEC (1986)
- Metal-graphite and silver-graphite brush grade data — Morgan Advanced Materials / Schunk / Mersen (2023)
- ASM Handbook Vol.2 — Properties of Copper–Graphite Composites — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.