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Do Your Servo Motors Look Like This: A Case for Standard Reconditioning

How Standard Reconditioning can vastly decrease the odds of a catastrophic breakdown

The machine environment can be a caustic one, with all kinds of opportunity for contamination to spew onto a servo motor.  Though your system and servo’s may be running fine, it’s only a matter of time before a buildup of contaminates (such as cutting fluids and metal shavings) will eventually creep inside the bearings and the stator and make a motor vulnerable to a catastrophic breakdown.  Contamination in the encoder and brake assembly due to improper maintenance is also common.  

Recent Job Report #4 -FANUC Alpha i Series AC Servo Motor Repair

Fanuc A06B-0265-B102

Here is a Fanuc Alpha i servo motor ready for assembly.

Repair Zone has been seeing an influx of newer generation Fanuc Alpha i Series servo motors and drives coming in for repair.  An Aerospace parts manufacturer in California sent us this Fanuc A06B-0265-B102 Alpha i servo motor for evaluation because it was increasingly noisey.  In our initial evaluation,

Quick Guide for Fanuc System Troubleshooting: Is it the Cable, the Amplifier, or the Servo Motor?

Checking a Fanuc system to find out why it is faulting.

Finding fault with a Fanuc servo system

When your CNC machine outfitted with Fanuc system stops working, the person running it or maintenance personal must quickly figure out the root-cause and then formulate a plan to get the machine running again.  Seems simple, but rarely is it simple or easy.

Being a Fanuc repair facility, a common happening is that we will get a Fanuc motor or amplifier in for service, then go through our process to evaluate and we find out: the unit runs fine

Your Options For Failed Allen Bradley Equipment: Repair, New, or Surplus


When your Allen Bradley equipment fails you have options.  You can choose to purchase the Allen Bradley equipment new from the Original Equipment Manufacturer (OEM), have the equipment repaired, or buy surplus.

There are many advantages to having your Allen Bradley equipment repaired versus buying new from the OEM, or purchasing surplus inventory.

Purchasing from OEM:

  • Many Allen Bradley series have been deemed obsolete and the OEM may no longer support your series
  • High expense
  • May need to replace entire system which can be costly
  • Long lead times can lead to lengthy downtime for your machine

10 Signs Your Servo Equipment Needs Repair

Fanuc Servo Motor needing repairIs your servo equipment noisier or less efficient than when you first purchased the equipment? Your servo equipment is probably ready for a thorough inspection, cleanse, repair, and simulated machine test.

The following list, discusses ten noticeable signs your servo equipment is ready for a repair, which can help save you from unexpected machinery downtime.

1. Noisy Servo Equipment

If your servo equipment is louder than usual, do not ignore the sound. When your servo components become noisier, the noise can mean the bearings have worn out, the keyway has worn out, the shaft is not fitting right, and/or the fans are not working correctly.

7 Reasons Your Servo Motor Breaksdown

7 Common Reasons for a Servo Motor Breakdown

A servo motor can be one of the most susceptible parts on your CNC machine or robot that may breakdown and require repair or replacement.  The environment in which it is placed can be violent and extremely dirty.  A servo is a very complex mechanism that needs all of its parts to work in unison for the whole to be successful.  Here is a guide to help you know what to look for when your machine will not run and your servo motor may be the culprit:

Drive Cabinet Air Condition fan contamination due to lack of filters. Cooling fan failures followed by drive failure due to overheat condition.

2 Reasons Why Your CNC Machine Will Break Down

By Jade York with Jonathan VanDenboom

The very nature of a CNC machine suggests an environment that can be harmful to itself and cause its own demise: Lots of lubricants and cutting fluids, oil, metal shavings, dirt and dust, etc. are everywhere.  Sound extreme?  Well, it is, and a recent visit to a manufacturing facility confirmed a long known fact: If not properly maintained, CNC and other machinery will fail sooner than later.

Choosing the Right Encoder for a Servo Motor

servo motor encoders

Connected to specific software, Scott measures the accuracy of the encoder counting – it was found to be counting correctly and in factory specifications.

Encoders are special sensors that capture position information and relay that data to other devices. They are used to determine the position, velocity and direction of a motor shaft or other mechanical motion. They provide information required for the precise control of a variety of applications, such as positioning a rotary table, pick and place, machine assembly, packaging, robotics and more.

By Joe Kimbrell

Encoders determine position using one of three technologies: optical, magnetic or capacitive.

The most accurate of the standard styles of encoders are the optical encoders. When choosing an optical encoder, it’s important that the encoder

Lifespan of a Servo Motor

assort_servo146fad2 higher quality

There is no specific time table for the lifespan of any servo motor. In ideal conditions a servo motor can last 20+ years, and under extreme conditions can last less than one year.  Most OEM (original equipment manufacturers) contribute the lifespan of their servo motors to the lifespan of the bearings.

Some of the OEMs have listed bearing lifespans (if properly lubricated) at:

Indramat: 30,000 working hours

Allen Bradley: 20,000 working hours

Case Study: Indramat Servo Motor Repair

Indramat servo for blog

Successful Indramat servo motor repair

Repair Zone received an Indramat servo motor for repair, in which the customer did not provide details of any issues.  The first thing our technicians did was meg test the coils to make sure the motor wasn’t grounded.  Next, the brake torque was checked and  a failure occurred, it wouldn’t release.  This possibly needed replacement.

Jason then disassembled the entire unit, and checked the encoder to make sure it was viable and functioning correctly.  The encoder was checked on a testing stand and we found no issues going through its rotations.

AC Servo Motor Repair: Encoder Re-Alignment- The Final Step


The expert technicians at RepairZone have a standard process they work through with every repair.  While there are multiple steps in the process of an AC Servo Motor repair, one of the final steps are one of the most crucial. This step is the encoder re-alignment.

  • If correct alignment data of a servo motor is unknown it must be gathered prior to disassembling the motor  in order to correctly realign during the assembly process.
  • When the motor has been disassembled, the encoder must be lined up again so it’s properly aligned with the magnets on the rotor and the windings of the stator.
  • If the encoder has been replaced, adjustment of the assembly is necessary.
  • Dynamic alignment (setting while under rotation) of commutation is accomplished by back driving the motor in the forward direction and using an oscilloscope to compare output of generated voltage of the stator/rotor to the corresponding commutation channel.
  • Oscilloscope traces from the line to line stator voltage and square waveform from the corresponding  hall switch represents one phase to phase voltage and one rotor position feedback signal.
  • Most units will have three position feedback signals that will match up to three line to line voltage outputs.
  • When feedback outputs are correctly matched with their voltage outputs, then adjusting one set of outputs will also adjust the remaining two.

The RepairZone technicians use manufacturer software and align the encoder to factory specifications.  Encoders differ greatly from brand to brand.  They are also very fragile and can be quite finicky.  After successful alignment, the motor is run-tested for 2-3 hours with a model specific drive or amplifier.   Without proper re-alignment, an AC servo motor simply will not work properly.

If you have any questions or need assistance, please call 989-922-0043.  To view our Servo Motor Repair capabilities  or Servo Motors in Stock at RepairZone, click the appropriate button below:

Servo Motor Repair Servo Motors in Stock

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Job Report #1-Fanuc Servo Spindle Motor Modification

spindle job 1

A customer shipped us this Fanuc Spindle Motor for repair and modification, to fit their application.  Jason, the lead Servo Technician at Repair Zone, had to fully disassemble and machine a keyway into the shaft.  Also, he had to machine the end bells and put new bearings on this unit.  Below is the pictorial of the process that took place, which included our machining center lending a hand.  (Above: Heating speed sensor ring for removal during disassembly)

How to Repair an Industrial AC Servo Motor

Repair Zone’s procedures require all major electrical and mechanical components making up the servo motor are independently tested upon motor disassembly.  Your servo motor will go through the following intensive repair process:

1. We first run a “Meg test” to check and see if any moisture potentially grounded motor.  If moisture has compromised the stator, the motor is disassembled and the windings are washed and baked.  Afterwards, the unit is Meg tested again.

   Step 1: Meg Test the Servo Motor   Step 2: Meg Test again after Moisture is Removed

Can You Run a Servo Motor with a Variable Frequency Drive?

Servo System

Testing Servo Motors and Drives

Can you run a servo motor with a Variable Frequency Drive? First, lets look at how a servo amplifier works with a servo motor.

A servo amplifier actually fires DC voltage into the three phases of a servo motor. Each time a phase is fired, it is completely dependent upon rotor positioning reference to the stator windings to be fired. In other words, you need commutation to run a servo motor. Most servo motors will have an encoder that is coupled to the rotor and aligned to give rotor positioning reference to stator windings.

We have actually ran a Yaskawa servo motor open-loop on a variable frequency drive (VFD) The results were not good. You see, no matter how we tuned the drive, the end result was a very inefficient motor that drew high amps and had no torque.  So the answer is:  yes, but not very well.

Top 5 Strategies to Keep Your Machinery Up and Running

Servo System Equipment

Find out how to keep your servo equipment up and running!

(1) Keep it Clean!!!

The most important strategy to keep your servo motors and industrial electronics running is keeping your servo motors and industrial electronics clean.

The filters, fans and heatsinks are the areas that require the most cleaning, because the filters, fans, and heatsinks are the most common fail points in your automation equipment due to the areas becoming clogged with oil mist and dust.

The heatsink, which its purpose is to draw heat away from the servo automation equipment, can cause overheating if it becomes clogged. When the automation equipment overheats, this can cause stress on the component and machinery, and eventually, the IGBT will blow up.

Allen Bradley 1326AB Brushless Servo Motors: Features & Benefits


Allen Bradley 1326AB Servo Motor

Allen Bradley products are known for being innovative and quality products. One common Allen Bradley product is the 1326AB series brushless servo motor; the servo motor is widely used in industrial automation machinery.

Three different feedback device options exist in regards to the 1326AB brushless servo motor: 1326AB-B____-M2L, 1326AB-B____-S2L and 1326AB-B____-21. The third segments of each different model number (i.e. M2L, S2L, 21) refer to the feedback options. The M2L refers to the absolute multi-turn high resolution, S2L refers to absolute single-turn high resolution, and the 21 refers to the resolver feedback option. The 1326AB brushless servo motor also comes in three different frame sizes: A (108 mm), B (149 mm) and C (194 mm), as well as a torque range of 2.7-50.0 Nm.

Features & Benefits

So, what makes your 1326AB brushless servo motor a great component in your automation machinery?

Features Benefits
Absolute encoder or resolver-based feedback Withstands intense shock, vibration
Withstands high temperatures
IP67 protection option rating Protects from harsh environments
Durable & high voltage windings Reliable operation
Advanced magnet design Has increased flux density
Greater demagnetization protection
Lowers harmonics and losses
Increased slot fill and better frame and magnetic structure Creates higher motor output
Sinusoidal, four-pole design Has predictable linear performance
Square torque-speed characteristic
Offers increased torque at high speed
Smart motor option Simple commissioning
Peak performance


1326AB Applications

The 1326AB brushless servo motor works best in applications that require smooth performance and high continuous output, such as the applications used in the automotive, machine tool and packaging industries.

Overall, the features of the Allen Bradley 1326AB brushless servo motor benefit your machinery by being a durable, reliable, and an efficient servo motor that will keep your machinery running longer with fewer issues along the way.

If your Allen Bradley Servo Motor needs repair or to view all of RepairZone’s Allen Bradley Repair capabilities, click on the appropriate button below:

Allen Bradley Servo Motor Repair Allen Bradley Repair Capabilities


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