
Power tools such as grinders, sanders, and jigsaws are helpful for different projects. But for these tools to work at their best, all the components, including switches and carbon brush caps, must work as expected. If you've noticed that your power tool is less efficient, the carbon brushes might be the issue.
That said, most people usually overlook carbon brushes when the power tool isn't functioning correctly. And for a good reason—carbon brushes don't wear down that fast. But carbon brushes, like every working part, eventually need to be replaced. After all, these components are always in constant rotational motion. Thus, they are prone to wear and tear.

Here's a guide on signs that it's time to replace your carbon brushes.
When To Change A Carbon Brush
It's hard to tell what's the right time to replace your power tool's carbon brushes. TDO Carbon says that the biggest sign of a carbon brush needing replacing is worsening power tool performance, which can manifest in having to shake the tool to get it going.
Below are other signs to look out for:
1. Inefficient Performance
The damage to the carbon brushes can occur after dirt and debris find their way into the carbon brush channel. Over time, the carbon brushes start to erode due to contact with dirt or dust while in motion. This situation causes the carbon brushes not to come into proper contact with the armature commutator. It then interferes with the current flow and causes the issue of no or low power generation by the power tool.
Due to the resulting inefficiency of the carbon brushes, it's a lot harder for the power tool to reach the maximum revolution per minute (RPM). And according to experts at constructionhow.com, your power tool can't complete the tasks it would have done before with ease.
2. Produces A Burning Smell
It's normal for power tools to produce a burning smell while running them, especially after using them for an extended period. The scent comes about due to heat and friction when running the power tool.
That said, check the carbon brushes when the power tool produces a burning smell after a couple of minutes or even a few seconds. The carbon brushes might have arched, thereby creating a burning smell. In such a case, shut down your power tool and physically inspect the carbon brushes. Check if they're worn out, and if so, go ahead and replace them.
3. Starts To Produce Sparks
Power tools like grinders produce sparks due to friction with other materials. The sight of sparks is also common when using power tools to perform routine tasks. But power tools generating large sparks indicate that the carbon brushes are worn out.
Sparks come about due to poor contact between the commutator and carbon brushes. Remember, there needs to be perfect surface contact between the commutator's arc and brushes. The sparks can also be due to the wearing out of carbon brushes, thereby releasing specks of carbon. These carbon specks then end up in the carbon brush channel and block the air vent.
So, examine how much sparks are produced through your power tool's vents. You'll then see if the worn-out carbon brushes are causing the sparks.
4. Visible Damage Or Discoloration
If the carbon brush shows signs of discoloration or physical damage, it's a sign they need to be replaced. And to do the physical inspection, look through the air vent to gauge the carbon brush's condition.
When you see any discoloration that comes about due to overheating, replace the carbon brushes right away. The same is true when the carbon brushes show signs of physical damage, such as breakage. Be quick to replace the carbon brushes, or else the issue will cause more damage to other components in your power tool. Ultimately, you'll spend more money replacing or repairing your mechanical tool.
5. Increased Electrical Consumption
When carbon brushes are worn out, they lose their ability to make proper contact with the armature of your motor. This means that the transfer of electrical energy is not as efficient as it should be, causing an increase in electrical consumption.
The motor then has to work harder to maintain its performance level, which leads to increased energy usage and can cause overheating. As the temperature of the motor rises, it becomes more prone to damage, and if left unchecked, it could lead to complete motor failure.
Takeaway
The breakdown of your power tool can interfere with how fast you get work done. The wearing down of the carbon brushes is sometimes responsible for the damage.
It's good to be proactive and look for signs indicating it's time to replace your carbon brushes. This guide outlines clear signs that your carbon brushes need replacement. Doing this will boost your productivity as you will no longer deal with your power tool breaking down at an inconvenient time.