Roundness Tester For DC Motor Or Universal Motor Maintain Stable Contact

Commutator Roundness Good Communication Testing Device For Brushed DC Motor WIND-RM-10

https://youtu.be/dJMY6JVncCY

(1) The purpose commutator roundness testing

If the commutator is not round, this increses the chances of incresed brush wear on the brushed DC

motor armature, as well as an increase in arcing and sparking of the commutator thereby destroying the

commutator surace, Good commutator roundness is very important for the armature performance.

Commutator roundness testing is important because the commutator is the sliding electrical contact surface of a DC motor or universal motor.

If it is not sufficiently round, the brushes cannot maintain stable contact during rotation. That causes several serious problems:

1. Brush sparking and arcing
   An out-of-round commutator makes the brush bounce up and down during rotation. This intermittently breaks contact and creates electrical arcing (sparks). Arcing damages:

• the commutator surface
• carbon brushes
• nearby insulation

2. Increased brush wear
   Poor roundness causes uneven pressure between brush and commutator. Some areas experience excessive friction, leading to:

• rapid brush consumption
• uneven brush face wear
• higher maintenance cost

3. Electrical performance instability
   Changing contact pressure changes the contact resistance. This can produce:

• unstable current
• torque fluctuation
• electromagnetic noise
• reduced efficiency

In precision motors, even small eccentricity can noticeably affect performance.

4. Mechanical vibration and noise
   An eccentric commutator behaves like an unbalanced rotating surface. The brushes repeatedly impact the high spots, causing:

• vibration
• audible noise
• mechanical fatigue

5. Risk of commutator bar damage
   Localized impacts and heating may loosen commutator segments (bars) or crack mica insulation. Severe cases can cause:

• lifted bars
• short circuits
• catastrophic rotor failure

6. Importance for high-speed motors
   At higher RPM, even tiny roundness errors become amplified because the brush impacts occur more frequently and with greater force. Therefore, roundness tolerance becomes stricter for:

• automotive motors
• power tools
• vacuum cleaner motors
• starter motors

Typical production purpose
In motor manufacturing, roundness testing is usually used to verify:

• turning/grinding quality after machining
• shaft and commutator concentricity
• deformation after molding or hot staking
• assembly accuracy

Common inspection methods

• Dial indicator runout measurement
• Roundness tester
•  
• 
• V-block + indicator
• Air gauge systems
• Online laser inspection systems

Related parameters often checked together:

• TIR (Total Indicator Runout)
• concentricity
• cylindricity
• segment height difference (“high bar”)

In practice, excessive commutator runout is one of the most common root causes of brush sparking problems in DC motor production.

(2) Technical Data

(3) Features

1. The high precision LVDT sensor is used for the roundness measurement, combining the analog and

digital filtering method into realization a high stability and rapid access to the sensor signal, to ensure

the high precision of the sensor signal.

2. Stepper motor is used as a driving source of measurement,combined with motor driven high subdivision

and high-speed pulse, ensuring the motor to run as smooth continous and measurement points

equidistant distribution.

3. The commuatator slot data recognition algorithm is unique, to ensure that the measurement results of

the data dones not include the gaps and the gap edge data, to guarantee the authenticity of the

measurement results.

4. When it measured on commutator bar also complete the detection of roundness quality surface to the

center axis at the same time, to find more accurate qualtiy armature.

(4) Competitive Advantages

1. Commutator surface turning quality is one of the importand factors that infulence the performance

   of armature, timely check the turning qulaity of commutator can provide an effective means of control

   the lathing quality.

2. The WIND-RM-10 Rotor roundness tester can deteck the armature commutator roundness fast and

    accurately, it is a fast and direct way to know the state of the armature production, can control the 

    product quality timely, control the production process and ensure the armature manufacturing quality.

3. High precision, no rust, rust, acid and alkali, no magnetization, no deformation, good wear resistance,

    the marble is used as a placement platform, V seat is placed on the marble platform, and the placement

    accuracy of the V seat is enhanced. The components (and connecting rod driving parts) drive the rotor

   (and the connecting rod drive parts) with two pairs of leveraged linkage lever mechanism synchronous

   clamp Tight rotor ensures smooth rotation of the rotor, ensuring the accuracy of the test.

   In conclusion, the utility model improves the automation degree of the rotor roundness tester in the

   existing technology, improves the production efficiency, saves the manpower,

   and improves the testing accuracy of the roundness tester. 

https://youtu.be/dJMY6JVncCY  English verison for roundness testing