Grade Information – Helwig Carbon Products, Inc.

Grade Info

One of the greatest challenges in manufacturing carbon brushes is supplying a grade that will maximize performance for the manner in which the motor or generator is operating. Consideration must be given to the actual running loads, duty cycle, voltage, peripheral speeds, and the environment.

Helwig Carbon’s technical staff is experienced in selecting the proper grade for your application. Choosing the wrong material could cause considerable damage to your equipment. However, overall, grades have been held more accountable for brush performance than is warranted. While selecting the proper grade is crucial, other factors often have a greater effect on brush performance.

Many of the grades used today are derived through variations in raw materials, molding pressure, temperature, duration of the baking process, and after-treatments. All brush grades fall into five categories:

  • Carbon Graphite
  • Graphite
  • Electrographite
  • Copper Graphite
  • Silver Graphite

Each material is designed and developed to perform under certain operating conditions. A best grade for each application is offered, although, several grades with similar characteristics may offer satisfactory performance.

CARBON GRAPHITE

Carbon graphite grades were developed early in the history of motors and generators. These grades, therefore, are found most often on older equipment, particularly those with flush mica commutators. Carbon graphite offers cleaning action for use at slow speeds, low-current densities and medium to low voltages.

ELECTROGRAPHITE

Electrographite is the most common grade used on modern equipment. With excellent performance at high voltages, high-current densities and high speeds, wide ranges of characteristics exist within this category. Most electrographite grades are capable of handling overloads.

GRAPHITE

Graphite grades are used in special applications requiring low-friction characteristics. When brushes must operate at very low current densities or very high peripheral speeds, a graphite grade should be used.

COPPER GRAPHITE

Copper graphite has a material content of 15 – 95% copper or copper alloy. The added conductivity and lower voltage drop, allows metal graphite brushes to operate at very high current densities and low voltages.

SILVER GRAPHITE

Silver graphite has a material content of 15 – 95% silver. The added conductivity and lower voltage drop, allows metal graphite brushes to operate at very high current densities and low voltages.

Grade Data

Many of the grades used today are derived through variations in raw materials, molding pressure, temperature, duration of the baking process, and after-treatments. All brush grades fall into five categories and are represented by the tables below.

Key for Performance Characteristics

Voltage Drop VH 2.5 and Higher H 1.9 to <2.5 M 1.3 to <1.9 L 0.7 to <1.3V VL Less than 0.7V
Coefficient of Friction H 0.3 and Higher M 0.2 to < 0.3 L 0.1 to < 0.2 VL < 0.1
Film Code 1 Mild Abrasive = Light Film 2 No Cleaning - Filming 3 Film Forming Properties = Med - Dark Film
 
VDCFFilmRated Current

Voltage drop, coefficient of friction, film code, and rated current are performance characteristics. Values shown are based on tests under one standard set of conditions, and are for use in comparison between grades only. On any application, the values could vary due to differences in operating conditions.

Resistivity Hardness Strength Rated Current
Grade OHM-IN µOHM-M Shore PSI N/mm2 VD CF Film # Amp/in2 Amp/cm2
H 0.0011 27 55 3000 20.7 M M 1 40 6.2
H250 0.0008 20 60 6700 46.2 M M 1 50 7.8
H357 0.0012 30 50 2800 19.3 M M 1 55 8.5
H422 0.01 197 50 3600 27.9 H L 1 60 9.3
H990 0.0027 67 70 4300 29.6 H H 1 40 6.2
NH12 0.032 800 45 3025 20.1 H L 1 55 8.5
NH16 0.02 500 25 2200 15.2 H VL 1 55 8.5
NH4 0.0016 40 45 2500 17.2 M L 1 50 7.8
Resistivity Hardness Strength Rated Current
Grade OHM-IN µOHM-M Shore PSI N/mm2 VD CF Film # Amp/in2 Amp/cm2
H22 0.00075 18 45 3000 25.6 M L 2 70 10.9
H23 0.0015 37 70 4500 31.0 M L 1 70 10.9
H24 0.0016 40 55 4100 26.2 M L 2 80 12.4
H25 0.0012 30 65 5100 35.2 M L 2 80 12.4
H27 0.0017 43 65 3900 26.9 H VL 2 80 12.4
H28 0.0018 46 45 2600 17.9 M VL 2 80 12.4
H3 0.00035 9 35 3500 24.1 M VL 3 70 10.9
H34 0.0022 55 75 4400 30.3 H L 2 80 12.4
H35 0.0022 55 50 2500 17.2 H L 2 90 14.0
H36 0.0022 55 70 3300 22.8 H VL 3 80 12.4
H37 0.0018 46 70 4400 30.3 H VL 2 80 12.4
H38 0.0020 50 80 5400 37.2 M VL 2 80 12.4
H39 0.0016 40 85 5400 37.2 H VL 3 80 12.4
H41 0.0025 62 60 3000 20.7 H VL 3 80 12.4
H43 0.0018 46 65 3700 25.5 M L 2 90 14.0
H4399 0.0008 20 45 4000 27.6 H L 3 80 12.4
H44 0.0017 42 85 5500 37.9 M L 2 80 12.4
H4430 0.0022 55 48 2500 17.2 VH L 3 80 12.4
H45 0.0025 62 55 3300 22.8 H VL 3 80 12.4
H46 0.0010 25 25 1500 10.3 M L 2 80 12.4
H47 0.0025 62 40 1500 10.3 H L 2 80 12.4
H49 0.0025 62 45 2000 13.8 H L 2 90 14.0
H50 0.0021 52 60 2900 20.0 M L 2 90 14.0
H51 0.0022 55 60 3200 22.1 M VL 2 80 12.4
H52 0.0022 55 60 2900 20.0 H L 2 80 12.4
H55 0.0011 27 50 3975 27.4 M L 3 75 11.6
H57 0.0021 52 50 2600 17.9 M L 2 90 14.0
H580 0.00036 9 40 3700 25.5 M L 1 90 14.0
H60 0.0021 53 75 5300 36 H VL 3 80 12.4
H61 0.0006 15 30 1500 10.3 M VL 2 75 11.6
H74 0.0030 75 55 1800 12.4 H VL 3 80 12.4
H76 0.0030 75 65 2400 16.6 H L 3 80 12.4
H77 0.0026 65 40 1800 12.4 H VL 3 80 12.4
H82 0.0016 40 64 5000 34.4 M L 2 80 12.4
H83 0.0017 42 70 3000 20.7 H L 2 80 12.4
H84 0.0017 42 80 5500 37.9 H L 2 80 12.4
HH 0.0006 15 40 3000 20.7 L L 1 75 11.6
Resistivity Hardness Strength Rated Current
Grade OHM-IN µOHM-M Shore PSI N/mm2 VD CF Film # Amp/in2 Amp/cm2
H552 0.0005 12 15 2000 13.8 L L 2 60 9.3
H610 0.0008 20 20 4700 32.4 M L 2 60 9.3
H619 0.0019 47 35 5500 37.9 VH L 3 50 7.8
H621 0.07 1778 45 4500 31.0 VH L 3 30 4.7
H646 0.01 250 30 5000 34.5 H L 1 60 9.3
H649 0.0098 245 35 2600 17.9 H L 2 65 10.1
H651 0.01 250 35 4300 29.6 H L 2 55 8.5
H700 0.0004 10 25 2300 15.9 M L 1 70 10.9
H702 0.001 25 15 700 4.8 M M 1 60 9.3
H704 0.0006 15 15 1000 6.9 M L 1 60 9.3
H7240 0.17 4250 55 4000 27.6 VH M 2 25 3.9
K018 0.0007 17.7 40 3000 20.7 M L 3 80 12.4
K094 0.06 1400 37 2100 15.9 VH L 3 30 4.7
K174 0.008 200 27 1900 13.1 H L 3 55 8.5
K194 0.003 76 25 4500 31.0 H L 3 55 8.5
K214 0.035 889 37 3000 20.7 VH L 2 55 8.5
K224 0.008 200 30 4000 27.6 VH VL 2 55 8.5
K244 0.04 1020 35 2600 17.9 VH L 2 40 6.2
K254 0.0009 30 40 3500 2.0 H L 2 80 12.4
K294 0.025 530 35 2000 13.8 H L 2 55 8.5
Resistivity Hardness Strength Rated Current
Grade OHM-IN µOHM-M Shore PSI N/mm2 VD CF Film# Amp/in2 Amp/cm2 Metal %
6H1 0.00026 6.50 30 2700 18.6 M L 1 100 15.5 30
6H2 0.00012 3.00 30 3700 25.5 L L 1 110 17.1 40
6H3 0.00006 1.80 25 3200 22.1 L L 1 120 18.6 50
6H6 0.0005 9.70 35 2500 17.2 M L 1 90 14 15
6H7 0.000033 0.64 25 3400 23.4 L L 1 130 20.2 65
6H8 0.000013 0.33 22 4500 31.0 VL L 1 140 21.7 75
H670 0.00018 4.50 40 5100 35.2 L L 2 110 17.1 40
H671 0.00025 6.30 50 6000 41.3 L M 1 110 17.1 30
H680 0.0000032 0.08 18 9300 64.1 L L 1 150 23.3 87
H682 0.000005 0.13 25 5100 35.2 L VL 1 140 21.7 75
H692 0.0000027 0.07 18 8800 60.7 VL L 1 160 24.8 90
H693 0.0000024 0.06 20 11500 80.0 VL L 1 175 27.1 95
H4333 0.00015 3.00 23 4000 27.5 VL L 2 130 20.2 40
H4375 0.0003 6.60 23 3000 20.7 VL L 2 110 17.1 30
K025 0.00014 1.80 25 3300 22.8 M L 1 120 18.6 50
K045 0.00011 2.80 25 4500 31.0 M L 2 110 17.1 40
K075 0.00026 6.60 25 4000 27.5 M L 2 100 15.5 30
K076 0.00002 0.50 13 13000 89.6 VL L 1 175 27.1 91
K085 0.0001 2.54 25 3300 22.8 M L 1 125 19.3 50
K086 0.000002 0.05 7 9000 62.1 VL L 1 160 24.8 91
K106 0.000004 0.10 8 6150 42.4 VL L 1 150 23.3 85
K107 0.000003 0.08 25 6500 44.8 VL L 2 130 20.2 59
K136 0.000013 0.33 18 4800 33.1 VL L 1 140 21.7 75
K165 0.0003 6.6 25 2500 17.2 L L 2 110 17.1 43
K175 0.00016 4.06 45 5000 34.4 L L 2 110 17.1 40
K176 0.000033 8.4 25 5000 34.4 L L 1 130 20.2 65
K216 0.00010 2.54 20 4000 27.5 L L 1 140 21.7 77.5
K236 0.00002 0.50 20 9000 62.1 L VL 1 150 23.3 85
K275 0.0013 33.02 25 4000 27.5 M L 2 80 12.4 27
K286 0.000015 3.00 5 6000 41.3 L L 1 160 24.8 94
K425 0.00019 4.82 25 5000 34.4 L L 1 100 15.5 42
K535 0.000004 1.02 25 5000 34.4 L L 2 110 17.1 50
K676 0.000014 0.35 25 5400 37.2 L L 2 120 18.6 67
K736 0.000007 0.17 20 7500 51.6 L L 1 130 20.2 73
Resistivity Hardness Strength Rated Current
Grade OHM-IN µOHM-M Shore PSI N/mm2 VD CF Film# Amp/in2 Amp/cm2 Metal %
K017 0.00005 1.27 20 3800 26.7 VL L 2 140 21.7 50
K037 0.000002 0.050 6 6000 41.3 VL L 1 200 31.0 91
K047 0.0003 7.600 25 4500 31.0 L L 2 100 15.5 29
K057 0.000008 0.160 20 5500 37.9 VL L 1 160 24.8 77
K087 0.00006 1.52 25 3500 24.1 VL L 3 130 20.1 50

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