Certifications All

image

Reviews and acts All

image

ISO 9001 2008

logo logo

 

PRODUCTS MADE OF GRAPHITE

 

Graphite and Copper-Graphite Electric Brushes

TSH-64-20183037-02:2010      

A brush of an electric machine is called a current conducting element which directly contacts with a collector or contact ring and which is designed to provide electric coupling of movable and fixed parts of an electric machine. At present time, brushes are made of various carbonaceous materials, graphite and of metallic powders. Brushes are applied in direct current generators and engines with average and hindered commutation conditions, in low voltage direct current electric engines of collector type with unobstructed commutation conditions. Graphite brushes are widely applied in every day life. Practically each electric razor, mixer, coffee grinder and electric drill contains a pair of electric brushes. Tremendous amount of graphite brushes is used in mining industry, EKG-5 and EKG-15M excavators, as well as in mechanical engineering and other sectors of industry. As a rule, all traction electric engines work using direct current and, therefore, have brush mechanism in its construction. External appearance of a graphite brush is determined its size, composition of materials used for production of brushes and its design.

 

  

 

We elaborated the following table for convenience of selection of an electric brush

 

           

The size of a graphite brush is expressed millimeters and stands out almost as the most important consumer characteristics, since it is this characteristic that is considered when placing an order. Depending on composition of materials, a finished brush is commonly called as a graphite, electric graphitized (electric graphite) or metal graphite brush. Electric graphite brushes are made of mixture of carbon-black, graphite and binding materials by way of hot pressing followed with burning to give mechanical endurance to a brush. Graphite brushes are technologically produced exactly in the same manner as electric graphite; however, the last state of processing thereof is carbon saturation of brushes in special furnaces at temperature of 2500 С during 45 days. As it is inferred from the name, metal graphite brushes consist of mixture of graphite and metallic powders (copper, tin and other).

 

            Main grades of most frequently used brushes are: MG and EG-84. The design of a brush assumes presence or absence of a conductor, nosepiece and cover. Section, length and type of conductor mounting are selected depending on special design features of a brush mechanism and current strength going through a brush.

 

Types of nosepieces which are used to connect a brush with brush holder stud.

 

 

A cover is located in the upper part of a brush and serves to distribute pressure force of a pressing spring to a greater area of a brush. Types of covers.

 

 

            There is a special type of graphite brushes: split-type brushes often called double brushes. Such brushes were specially designed to improve contact a brush with a collector if there is high vibration. The most important characteristics of graphite brushes is hardness thereof. In respect to hardness, graphite brushes are distinguished into soft, medium hard and hard. As applied to electric graphite brushes: brushes of EG-4 and EG-71 grades are soft, brushes of EG-14 grade are medium hard, and brushes of EG-8 and EG-74 grades are hard. Brush EG-14 was specially designed as a universal one in order to replace an electric graphite brush of any grade, if necessary. Hard graphite brushes operate in hindered commutation conditions and high temperatures. Such brushes are introduced with a special abrasive powder which gives cleaning properties to a brush. Such brushes not only just transmit electric current to a collector but also clean it from scale.   

         

 

 «ЗНАК» Attention! Taking into account the composition of graphite brushes, do not use them instead of brushes of other grades, even if they fully match in sizes. Consequences of incorrect selection of an electric brush results in failure of a collector of electric engine which can not be repaired, thus necessitating purchase of a new electric engine. Reference designation or marking is an important feature of any brushes. When selecting electric brushes, pay attention to marking, reference designation, hardness and electric resistance.

 

 

 

 

If you have difficulty in correctness of selection of a graphite brush for of your electric engine, then our specialists are ready to provide assistance to you at any time to make a right selection.

 

«Having made the right selection, you extend the service life of your electric engine»

  

 

Electric Graphite Contact Inserts and Skids.

 TSH-64-20183037-05:2012

 (Originally Developed in Uzbekistan for Railway Transport)

            

Electric graphite contact inserts and skids are designed for current receivers of electric rolling stock of railway transport. Electric graphite contact inserts are made of natural graphite, industrial carbon and binding materials by way of hot pressing.

Skids are made of aluminum alloy by way of extrusion.  This technology for production of inserts and skids was developed for new electric locomotives of «Uzbekistan» series of SJSCRC «Uzbekiston temir yullari».

 

 

Physical and Mechanical Properties of Inserts and Skids

 

Indicator Name

Indicator Value

Electric Graphite Inserts 

Skids

Actual

Standard

Actual

Standard

1. Hardness.10 PA

30

30

70

70

2. Specific Electric Resistance, mkm/m

22-30

30

0,45

0,45

3.  Density, g/cm

1,73

1,73

2,7

2,7

4. Water absorption in %, no more than

0,17-0,19

0,2

0,09

0,1