Electrical motors play a vital role in the operation of industrial machinery across industries. Using the right type of motor, implementing a machine maintenance schedule and ensuring any repairs are carried out effectively is essential to ensure the smooth-running of your facility.

In this guide, we provide information about the basics of industrial DC motor repair.

 

DC Motor basics

DC motors are types of motors that use a direct current to convert electrical energy into mechanical energy. In this way, they differ from AC motors which use an alternating current.

This type of motor can be found in a huge range of industrial equipment. There are four main types of DC motors, which are: Shunt wound motors, series wound motors, permanent magnet motors and compound motors. Along with the difference in input power, these motors are also capable of producing a higher torque than AC motors and also offer better speed control.

The main components of a DC motor include a stator and an armature. The stator is the stationary component of the motor and the armature rotates around the iron core. The stator provides the energy required for the armature to rotate.

Like other industrial machinery components, regular maintenance is required to ensure the longevity and functionality of DC motors. This includes performing regular checks such as:

• Reviewing the service history
• Noise and vibration inspections
• Visual component inspection
• Windings tests
• Brush and commutator maintenance
• Bearings and lubrication.

 

Sometimes repairs are necessary, so it’s important to know how to carry these out appropriately. Replacement parts might be required, and you can find a range of industrial automation equipment spare parts on the Preferred Spares website. Additionally, the experienced team can assist with advice about how to carry out effective DC motor repair.

 

Common DC motor repairs

Read about some of the most common DC motor repairs you should know about. 

DC motor rewinding

It might be necessary for the DC motor to be rewound to achieve acceptable motor performance. This involves unwinding the old rotor and stator windings and replacing them with new ones sourced from a reputable and reliable spare parts provider.

When this process is required, be sure to check the specific measurements and documentation of the motor, but often this will require a professional to carry out correctly.

 

Bearing failure

Bearing failure most often occurs as a result of natural wear and tear to the motor due to unsatisfactory lubrication such as when it is over or under-greased, or if lubricants are contaminated with other particles that can cause abrasion.

This can cause electrical issues due to the current passing through bearings which can lead to surface damage (known as fluting). Bearings must be replaced and measures taken to ensure they remain properly isolated from electrical currents in the future.

 

Commutator replacement

The commutator is an attachment connected to the armature of the DC motor which ensures that the current flowing through is a direct current.

As such, it plays a vital role in any DC motor. Damage to this component must be dealt with swiftly and the commutator replaced to avoid downtime or further damage to the motor.

Find a range of commutators and other DC motor spare parts on the Preferred Spares website.

 

Grooving, streaking, threading, and photographing 

Grooving occurs on the commutator brush path and appears as smooth grooves. This damage can be caused by a brush that’s improperly installed or using a brush that is too abrasive. Additionally, it can be caused by humidity and temperatures that are too low.

Streaking also refers to damage to the commutator that appears as thin dark marks in the brush path, which can be caused by issues such as contamination, high humidity, low spring pressure or improper current load.

Threading is another form of DC motor damage that requires repair. It appears as thin lines (that look like threads) on the brush paths within the commutator and can cause issues such as excessive carbon dust and increased brush wear. To repair the operator must machine the commutator.

Photographing appears as large dark streaks that take up the width of the brush and brush path. This occurs as a result of condensation under the brush face or an interruption of current at the same time, and in the same rotation, as the commutator.

 

Marking and burning & copper drag

Marking and burning on the commutator often indicate problems with DC motor function. Slot bar marking appears on alternate commutator bars as dark or discoloured marks and is caused by uneven current distribution or poor armature winding. Burning can indicate that the brush alignment is incorrect or that there is low spring pressure.

Copper drag is another problem that appears as smears and is caused by excessive heat that softens the commutator surface. Although not always, this can indicate a more severe issue and must be dealt with as soon as possible.

 

DC motor brush replacements

DC motor brushes wear down over time as a result of regular usage, and they will eventually require replacing as worn brushes can affect performance and cause damage to the armature winding and commutator.

If brushes are installed incorrectly or there are issues with windings, voltage surges or sparking it can cause premature brush wear and require a replacement before it is due. If this is the case, the motor brushes must be replaced to ensure functionality and prevent machine downtime.

 

Find a range of DC motor replacement components with Preferred Spares

It’s no secret that a lot can go wrong with a DC motor. Knowing the signs and ensuring you take action quickly when repairs are required is essential if you want to preserve your machinery and avoid downtime as a result of issues that can be solved with a simple repair or replacement part.

Some repairs, like brush replacements, are much simpler than others such as armature or field coil rewind. Carrying out regular maintenance and recognising the signs is critical in an industry setting.

 

 

Preferred Spares sources and supplies a huge range of industrial machine and DC motor spare parts from the world’s top manufacturers and provides reliable, expedient delivery across the region. Additionally, their expert team can offer DC motor repair advice and maintenance tips to help prevent further damage and increase the lifespan of your equipment.

 

To find out more or to explore the range of DC motors and spare parts available, visit the Preferred Spares website today.