Don't Just Shelve It: Care for Spares

Your spare parts deserve some maintenance TLC to ensure they’re ready to run.

We think of routine care and maintenance of a system to stave off failures as standard practice, but what about preventive maintenance of the replacement parts used when the system does fail? It’s easy to forget about spares sitting on the shelves when systems are running smoothly and there’s no need for them. This could be a costly mistake, however, when a drive goes down and the next in line has been sitting untouched in the same spot for more than a year. To keep spares useful and running for years, proper planning, maintenance, and storage are vital.

Standardization will set you free

The first step to saving money on the back end with respect to spare parts is good planning in the design system. Controls, motors, and drives all work together with a common goal and can use common components as well. Designing a system with standardized motors and drives provides an operator with the ability to put fewer backups on the shelves because specific parts can be used in more than one place.

Induction motor standards usually are based on the size of the shaft or the bolt circle, so pay specific attention to those measurements to be able to use one spare across multiple parts of a system. For example, if a motor is being applied to conveyors, it makes more sense to standardize the parts with the right size and selection and just keep one spare with a large amount of horsepower. If the spare motor in storage is a 3-hp motor, it can be used anywhere in the conveyor to replace a motor ranging from 1–3 hp, as opposed to having a backup for each component. The same concept can also be applied to drives as long as the tuning parameters for each application are always on hand.

Take care of the spare

Just like food sitting on a shelf, spare motors and drives can expire in storage – notably, if they are not regularly used and cleaned. “Regularly” might seem like a word that suggests frequent attention, but performing routine maintenance on spares once or twice a year is all that is necessary. For example, look at most variable-frequency drives. One of the common components in these is an electrolytic capacitor. If used regularly, it will keep working, but if it sits on a shelf untouched for an extended period of time, it will die just like a battery. It’s important to reform a capacitor after it has been in storage in order to revamp the voltage; this is as simple as hooking up the drive to a variable power supply and increasing the voltage slowly over a period of 15 minutes. Most manufacturers have written procedures for routine maintenance, so as long as the spare is on the shelf, it’s a good idea to follow the guidelines that accompany it.

Storage of spares is just as important as spares maintenance. Conditions and environments don’t differ much for motors vs. drives. Cool, dry storage is a must for both system components. When it comes to drives, dust and dampness are especially detrimental.

A good rule of thumb is this: If it’s not appropriate storage for a computer, it’s not appropriate storage for a drive. Motor spares can have a few more stipulations when it comes to shelf life. Exposing them to dust and elements should be avoided, and the lubrication should be checked every couple of years. Given the numerous different types of motors, it is best to consult with the manufacturer for specific storage requirements for each.

Plan ahead or fall behind

Failures within a system are inevitable, so being as prepared as possible for when they do occur is the best way to prevent a loss of profit. Drives and motors usually go down, but they rarely do at the same time. Condensing inventory of spares for each component is a cost-effective and easy way to streamline backup of a production line.
Preventive maintenance of spares ensures there will be no time lost when the part is needed because a backup that has been neglected for too long fails. Neglecting parts in storage increases the chances of prolonged issues in a system, so keeping track of backup inventory always will save money in the end.

Written by:  John Brokaw, a Senior Application Engineer for Valin Corp., for Plant Services.