How to handle a request for a harder or softer brush grade.

Customers frequently make requests for a harder or softer carbon brush. For instance, they might request a harder brush grade in order to get better brush life or to prevent excessive dusting. Before proceeding with their request, it’s important to understand the application and get to the root cause of the problem. Often, the carbon brush grade is not the reason for poor performance in the brush circuit.

When a motor OEM manufactures a motor, they engineer it to operate within the parameters of the nameplate. Usually, little consideration is given to the application, environment, ambient outside temperatures, humidity, duty cycle, etc.…
The first thing that needs to be done is to gather information. The list below is extensive, but it contains all the information needed if you want the motor/generator to run efficiently and brush life to be maximized.

1. What is the problem that needs to be resolved by moving to a harder or softer grade?
2. What is the condition of the brush holders?
3. What is the condition and design of the springs? What is the spring force?
4. What is the condition of the contact surface (commutator or slip ring)?
5. What is the environment like (climate, ambient temperature, humidity)?
6. What is the application (paper, steel, concrete manufacture, annealing, etc.)?
7. What type of cooling is used (blower, inside or outside air)?
8. What is the duty cycle?
9. What is the load?
10. How many total brushes are being used?

When all this information is taken into consideration, the data can be reviewed and run through a few formulas to determine the proper brush and grade for the motor or generator application. It’s possible that the application may call for a different carbon grade. However, the issue could also be related to spring pressure, the numbers of brushes, bad surface conditions, or other factors. Collecting the data above will enable Helwig Carbon engineers to make a recommendation on how to maximize the brush life and performance.

Helwig Carbon also has expert Field Service Representatives that can assist you to diagnose issues and assist with solutions on site.

Please contact us or go here to find your local Field Service Representative.

Michael A. Burke Sr.
Field Service/Sales Representative for Texas, Oklahoma, Arkansas & Louisiana
Helwig Carbon Products Inc.