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Servotech Offers Spindle Repair

Refurbished spindle motor from Servotech.

In an industry aimed at maximizing productivity, manufacturers will always want to get the most out of their equipment. The spindle is no exception. Spindle motors are the workhorse of any manufacturing facility, found in all applications, operating in harsh conditions for long hours. Because of their vital role, when a single spindle motor goes down, it is not unusual for entire production lines to come to a halt. Having a contingency plan in place is crucial to getting your operation back up and running. With many companies reporting a lack of skilled workers, completing an in-house repair has become an unlikely option. In addition, due to economic down turn, purchasing a spare motor has also become less common. Likewise, purchasing a new motor may not only be cost prohibitive, but also unmanageable. Some spindle motor replacements are currently at twenty-week lead times. For all of these reasons, repair is an important asset to any business, big or small.

Spindles must be repaired with two major considerations in mind. Electrical components are the first, which specifically pertain to the feedback device and the windings. The second major aspect is mechanical. High speed feedback devices need to be operating properly. The greater speeds and forces acting on a spindle mean greater consequences for a sensor failure. The most common form of feedback found on spindles are magnetic proximity sensors. These are analogue devices that rely on magnetic wheels to generate electric wave forms to very specific voltages. It is crucial that the circuitry of the sensor be in good condition and properly defended from moving parts. Tantamount to the sensor, the magnetic wheel must retain its magnetism which can easily be ruined if it is struck or heated to excess. Successful repair of a spindle starts and ends with being able to safely remove a sensor and reinstall it properly so that it will run again when it has been rebuilt. It is also important to maintain the integrity of the windings, which may even need to be wound depending on how badly the spindle has failed. Coolant is a powerful substance that aids in the machining process but if it gets inside a motor it will corrode the soft copper windings.

Equally as critical to a successful repair are the mechanical considerations that go into spindle repair. High speed motors are intrinsically more delicate, have tighter tolerances, require high speed bearings, precision balanced rotors and a good sealing strategy. Standard bearings can stand up against dirt and moderate amounts of contamination in a way high speed bearings cannot. Ultimately the goal of repair is to bolsters a motor's resilience to the conditions that caused the failure. High current alarms can be addressed by upgraded bearings, high speed grease and different seals which offer lower friction. The fits and journals on which the bearings rest cannot simply be machined, they need to be chromed and ground to factory specifications.

Rotors need to be balanced so as to not cause excessive vibration. After the motor has been rebuilt it is vital that a vibration analysis be done. SpindleScope is an excellent program available for the iPad, which can identify imbalance and potentially harmful vibration. Rotors get balanced when the motor is disassembled. Perfectly balanced rotors are only a piece of the puzzle. Programs like SpindleScope allow for analysis while the motor is built and running which can offer insight into hard to anticipate, malignant conditions. Any and every part on a spindle has the potential to carry a hidden factor that causes or contributes to spindle failure.

Attention to detail is the heart of spindle repair. Overt circumstances like excessive contamination can mask subtle conditions that will cause more elusive types of failure. Maintaining vigilance on all variables, mechanical and electrical, is the key to repairing a spindle motor. Each repair should be protected by an effective sealing strategy. The advances of technology in the manufacturing world bring with them new challenges to the operation of parts makers. Spindle motors are at the apex of the industry and need to be up and running long hours. In the event of a failed spindle, repair, though difficult and complex is the right choice for minimized downtime and maximized quality.

Authored by Christian Ratliff, Lead Technician, Servotech, Inc.

For more information contact:

Servotech, Inc.

478 Timber Ridge Road

Middletown, CT 06457


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