Professional power tools place the highest demands on electric motors. Carbon Brushes of this equipments are compelled to work under difficult situations such as :

• High Current Densities
• vibration
• Dust Formation
• High Rotational Speeds
• Exposure to weather conditions etc.

G35 Grade Carbon Block is specially made to work under such conditions. Carbon Brushes made from G35 Grade carbon blocks have shown excellent performance in this field. in additional to research and development , it is the right materials choice combined with superior process technology in our mixing plant with our modern production technology which ensures the high quality of our products.

Carbon Brushes made of G35 grade carbon blocks experience a long operating life and high operational reliability. In addition to Long life , Carbon Brushes made from G35 also possesses extra qualities such as :

• Not to damage Commutator
• Lower Level of radio interference
• To endure vibration , impact and in some cases even electric brakes work

With G35 Grade excellent test results have been achieved with small and large angle grinders. some of the noteworthy results seen are :

• Remarkable increase in lifetime of brush and commutator
• Low commutator wear
• Lower operating temperatures
• Low RFI

Power Tools : Carbon Brush is used in the power tools such as drill , circular saw and grinder etc.

Home Appliances : Carbon Brush is used in the electrical vacuum cleaner , juicer , mixer , hair dryer , and health apparatus etc.

Carbon Blocks

1. 127 x 77 x 18 MM
2. 127 x 77 x 20 MM

Apparent Density	Resistivity	Hardness	Transverse Strength
1.57 gm / cc	40000 - 60000 miro ohm-cm	32 - 37 HSD ( scleroscope )	250 Kg / cm2

Moreover carbon blocks can also be supplied upto 45mm thickness if required.

The Purpose of this guide is to promote awareness of undesirable carbon brush operation. Early Recognition and corrective action can help avoid costly unscheduled down time.The commutator film condition is a primary indicator of the performance of any motor generator. A consistent color over the entire commutator in the brown tones from light tan to dark brown indicates a satisfactory film condition. in these cases sufficient film exists for low friction operation while there is not excessive film to restrict proper flow of current. inconsistent film color and deformation of the commutator surface are warning signs for developing trouble conditions with fast brush and commutator wear.

Fast Wear : Accelerated brush wear due to a variety of conditions causing excessive dusting or arcing.
Cause : All of the definitions listed below will contribute to fast wear. Also roughness or irregularity of the commutator surface such as high bars , mica or burrs , or an out of round contact surface condition will cause radial movement and resulting arccing and chatter.
Recommendations : Check that commutator is in good condition , that spring pressure is adequate at the face of the brush , and that the proper number of brushes are in use based on operating current densities.

Light Load : Low Current Density for the grade in use or in adequate filming or high friction condition
Cause : Equipment is set for the maximum loads and the product dictates operation at less than nameplate resulting in light Load , high friction , brush dust and eventual threading.
Recommendations : Increase current density by removing brushes or consider light load filming grade.

Threading : The copper transfer from the rotating surface to the brush face and the resulting wear on the contact surface from metal to metal abrasion.
Cause : Often due to low current density and in adequate spring pressure. May also be worsened by contamination.
Recommendations : Verify actual operating nloads and spring pressure to be sure they are in the proper range for the grade in use. if possible , eliminate any contamination present.

Grooving : The result of abrasiveness or excessive electrical wear of contact surface or ring surface.
Cause : Most commonly due to poor electrical contact resulting in arcing and electrical machining of the commutator. Can also be due to mechanical wear or overly abrasive grade. in adequate spring pressure , low current densities or excessive current are also possible causes.
Recommendations : Check the contact surface that roundness is within .002" with less than 0.0003" variation from bar to bar. Vibration should be less than 6 mils. Check current density and spring pressure.

Arcing : Arcing and burning at the brush face.
Cause : Due to poor electrical contact , in adequate spring pressure (See Chart) rough commutator , or ring deposits or burrs in brush holder.
Recommendations : Contact surface should be round within .002". Check spring pressure to ensure that it is 4-6 psi for industrial DC applications and remove any deposits in holders.

Chipping : Brushes chipping or breaking at the face.
Cause : Roughness or irregularity of commutator surface , high bars , mica or burrs can breake the entering edge of the brush and cause brush bounce or chatter.
Recommendations : Check contact surface condition to be sure it is within tolerance check spring pressure and running loads .

Spring Pressure : The most common cause of unsatisfactory film condition is in adequate spring pressure. For reference the chart below indicates the recommended ranges of spring pressure for various applications and the method for calculating spring pressure from the measured spring force.