My previous post on repair versus replace decisions during motor failures touched on the need to maintain spares for your critical motors. This post delves into motor-specific considerations for your comprehensive spare parts management policy.
With today’s emphasis on lean and just-in-time manufacturing, the objective of any spare parts management program is to ensure timely availability of spares in the event of failure while minimizing inventory. On-site spares and vendors with quick turnaround times help to minimize your downtime — and your spares inventory.
Maintaining spare motors racks up inventory costs quickly; however, a well-managed spare motors inventory can improve your bottom-line. Here are some of the best practices that you can follow to improve management of your spare motors inventory:
1. Identify your critical motors.
Get to know your motor inventory: identify and classify your motors based on their criticality. While different philosophies use different terms for each level, I like the four-tiered scale below that defines an asset’s criticality by influence on production or service delivery.
| CRITICALITY | DEFINITION | SPARE MOTOR PHILOSOPHY |
| Vital | Downtime zeroes your revenue | Stock on-site through purchase or consignment |
| Critical | Performance affects revenue | Identify vendor who can stock locally; able to get on-site within 2- to 4-hours |
| Essential | Downtime strains production / compliance | Identify vendor who stocks regionally; able to get on-site within 2- to 4-days |
| Non-critical / Desirable | Downtime won’t immediately affect revenue / compliance | Go to bid to identify lowest cost vendor |
Ensure the availability of spares for vital motors by either stocking them in-house or keeping on-site on consignment with your preferred vendor. For motors not stocked on-site, check availability of spares quarterly (scarce / difficult / available analysis). Many motor manufacturers produce motors in batches, meaning the available stock for certain size and speed motors varies. Critical and essential spare shortages can lead to higher prices — or worse, an operational shutdown.
Your spares management program should align with your operational objectives and drivers, and apply standard inventory management strategies, like automatic replenishment for any spares that you decide to stock, timely replacement when inventory levels fall below the re-order threshold.
2. Compare carrying costs to downtime.
Maintaining a spare motors inventory can be expensive. Costs include purchasing, storage, material handling, security, labor, and inventory carrying costs such as obsolescence, depreciation, insurance and taxes. Tying up your funds in spare parts also carries an opportunity cost versus potential other capital investments. But downtime is often even more expensive. Comparing inventory costs with spare part availability and equipment downtime cost will help you to strike a balance that maximizes your return on any spares investment.
3. Maintain your spares.
Spare motors require care and monitoring. Inactive motors are susceptible to rusting, corrosion, eccentricities, and bearing issues. Protect your motors from corrosion, re-lubricate bearings periodically, rotate shafts monthly, power spares on (no-load) annually (be sure to take appropriate safety precautions around rotating equipment), and remove dust build-up regularly to ensure your spare motors work when you need them.
4. Hire a spares management firm.
Increasingly, firms use outside vendors to manage their spare parts inventory. In addition to reducing (or even eliminating) inventory carrying costs, spares management firms enable you to share the risks associated with obsolescence, shrinkage, overstocking, and depreciation. These supply-chain-management vendors also often bring industry-specific expertise on failure rates of similar equipment and benefit from economies of scale on the price of spares they stock.
An effective spare parts management policy reduces downtime and improves your bottom line. For more information on how our software can help you proactively plan for or even prevent future motor failures, contact us at info@motorsatwork.com.