The Hidden Costs of Spare Parts Management Failures

Step 1: Identify Your Critical Spares

Not every component in your control system needs a place on the spare parts shelf. The aim is to prioritize the parts that could halt production completely if they fail.

Here’s a simple way to define “critical”:

• • • Can it shut down operations if it fails? If yes, it’s critical.
    • Is it hard to source quickly? If yes, it’s critical.
    • Does it take specialized setup or configuration? If yes, it’s critical.

Common Examples of Critical Spares

• • • CPUs and controllers — without them, the entire process halts.
    • I/O cards and communication modules — often single points of failure.
    • Power supplies — inexpensive, but a common cause of downtime.
    • Specialty modules or legacy hardware — harder to replace on short notice.
      
      

Pro Tip: Don’t build this list in a silo. Engage both your maintenance team (who know what fails most often) and your operations team (who feel the impact when it does). Together, they’ll identify what’s truly critical for uptime.

Step 2: Prioritize by Risk and Lead Time

Once you’ve identified your critical spares, the next step is to prioritize them based on urgency. Not all parts pose the same level of risk, and not all require the same stocking approach.

Here’s a simple way to prioritize:

• • • Failure likelihood: How often does this component fail in real-world use?
    • Production impact: What happens if it fails — a slowdown or a full shutdown?
    • Lead time: How quickly can you realistically get a replacement?
      
      

When you consider these factors together, you can create a clear priority list. The goal isn’t to stock everything — it’s to direct resources where they’ll make the biggest impact.

Example Breakdown

• • • High risk / long lead time: Controllers, legacy I/O cards, specialty modules → keep spares on site.
    • Medium risk / medium lead time: Power supplies, communication modules → stock at least one backup.
    • Low risk / short lead time: Common sensors, cables, HMIs → order as needed, but verify availability annually.

Pro Tip: Don’t only consider cost when ranking options. A $300 part that takes 12 weeks to replace could be a bigger risk than a $5,000 part that can be shipped overnight.

Step 3: Tie Stocking to Lifecycle & Modernization

It’s tempting to think of spare parts management as just stocking shelves, but overstocking obsolete hardware can waste money and slow down necessary upgrades. The smarter approach is to tie your spare parts strategy directly to vendor lifecycle updates and your plant’s modernization plan.

Here’s how to align the two:

• • • Monitor lifecycle notices: Major vendors issue bulletins stating when hardware becomes “mature” or “discontinued.” If a component nears end-of-life, plan spares carefully.
    • Stock to buy time, not avoid upgrades: Having critical spares provides your team with breathing room — but it shouldn’t replace the need for system modernization.
    • Avoid over-investing in outdated hardware: Buying too many spare parts for a system that is nearing end-of-life ties up funds that could be allocated for upgrades.
    • Use phase-outs as early warning signals: For example, Siemens’ upcoming ET 200M transition serves as a reminder that all platforms eventually phase out. Rockwell, ABB, and others have their own schedules — and plants that monitor them stay prepared.

Pro Tip: Ask your vendors and integrators for lifecycle updates at least once a year. Incorporating spares strategy into upgrade planning helps prevent stocking shelves with parts you’ll soon phase out.

Step 4: Implement a Review & Ownership Process

Even the best spare parts plan can fail if it’s not properly maintained. Components change, systems evolve, and what was critical last year might not be relevant today. That’s why a spare parts strategy requires regular review and clear ownership.

Here’s how to keep it effective:

• • • Establish an annual review cycle: Audit your spare parts list and inventory at least once a year to account for new equipment, lifecycle changes, and usage trends.
    • Assign ownership: Identify who is responsible for managing the spare parts program — whether it’s a maintenance lead, reliability engineer, or a cross-functional team.
    • Track usage and replacements: Keep clear records of when spares are used, reordered, or retired. This prevents “invisible gaps” from creeping into your inventory.
    • Watch for shelf rot: Electronic components and specialty modules can degrade if stored too long. Rotate stock and check the condition to avoid relying on parts that might not work when needed.

Pro Tip: Consider spare parts as a living asset rather than just static inventory. Keeping ownership clear and reviews consistent ensures your plan remains relevant and dependable.