# Understanding when to use time-based scheduling versus condition-based monitoring — and how to combine both for the best results.

## Introduction

Preventive maintenance can be triggered in two ways: based on time or based on equipment condition.

Both approaches aim to prevent equipment failures — but they work differently and suit different situations.

This guide explains how each strategy works, the pros and cons, and how to decide which approach is right for your assets.

## What is Time-Based Maintenance?

Time-based maintenance (TBM) schedules servicing at fixed intervals — regardless of the actual condition of the equipment.

Examples:

- Lubricate bearings every 30 days
- Replace filters every 3 months
- Inspect safety systems weekly
- Full equipment service annually

TBM is simple to implement and works well for assets with predictable wear patterns. It forms the foundation of most [preventive maintenance](/content/preventative-maintenance-software/index.html) programmes.

## What is Condition-Based Maintenance?

Condition-based maintenance (CBM) triggers servicing based on the actual condition of equipment — using real-time data from sensors and monitoring systems.

Examples:

- Replace bearings when vibration exceeds a threshold
- Service cooling systems when temperature rises above normal
- Investigate motors when power consumption patterns change
- Replace oil when analysis shows contamination

CBM requires [IoT sensors](/content/iot-maintenance-software/index.html) and monitoring systems but provides more targeted and efficient maintenance. For a detailed guide, see our article on [IoT condition monitoring](/content/blog/iot-condition-monitoring-guide/index.html).

## Key Differences

| Factor | Time-Based (TBM) | Condition-Based (CBM) |
| --- | --- | --- |
| Trigger | Calendar or usage intervals | Real-time sensor data |
| Data Required | Schedules only | Continuous monitoring data |
| Implementation | Simple — schedules and checklists | Requires sensors and integration |
| Over-Maintenance Risk | Higher — may service unnecessarily | Lower — based on actual need |
| Under-Maintenance Risk | Possible — issues between intervals | Lower — continuous monitoring |
| Cost | Lower upfront | Higher upfront, lower long-term |
| Visibility | Only during inspections | Continuous and real-time |
| Best For | Predictable wear, simple assets | Critical, complex, high-value assets |

## Pros and Cons

### Time-Based Maintenance

**Pros:**

- Simple to set up and manage
- No sensors or monitoring technology required
- Works well for assets with predictable wear
- Easy to standardise across an organisation

**Cons:**

- May service equipment that doesn't need it
- Problems can develop between scheduled intervals
- No real-time visibility into equipment condition

### Condition-Based Maintenance

**Pros:**

- Maintenance only when data shows it's needed
- Continuous visibility into equipment health
- Reduces both over-maintenance and under-maintenance
- Enables [predictive maintenance](/content/blog/what-is-predictive-maintenance/index.html)

**Cons:**

- Requires investment in sensors and monitoring systems
- More complex to implement initially
- Not cost-effective for all assets

## When to Use Time-Based Maintenance

TBM is the right choice for:

- Assets with known, predictable wear patterns
- Simple equipment where the cost of monitoring exceeds the benefit
- Compliance-driven inspections that must happen at fixed intervals
- Organisations just starting their preventive maintenance journey

## When to Use Condition-Based Maintenance

CBM is the right choice for:

- Critical equipment where failure causes major disruption
- High-value assets that justify monitoring investment
- Equipment with variable or unpredictable failure patterns
- Environments where downtime is extremely costly

## Combining Both Approaches

In practice, the most effective maintenance strategy combines both TBM and CBM.

A practical approach based on asset criticality:

### Tier 1: Critical Assets

Use condition-based monitoring with IoT sensors. These assets justify the investment because failure is extremely costly.

### Tier 2: Important Assets

Use time-based [scheduled maintenance](/content/maintenance-scheduling-software/index.html) with regular inspections. Supplement with basic monitoring where practical.

### Tier 3: Non-Critical Assets

Use simple time-based schedules or run-to-failure where replacement is cheap and failure has minimal impact.

This tiered approach ensures you invest monitoring resources where they deliver the most value.

## How a CMMS Supports Both Strategies

A [CMMS](/content/cmms-software/index.html) supports both time-based and condition-based maintenance by:

- **Automating schedules** — generate [work orders](/content/work-order-management-software/index.html) at defined intervals
- **Integrating with IoT sensors** — trigger maintenance based on real-time data
- **Tracking [asset history](/content/asset-management-software/index.html)** — build a complete record of all maintenance activity
- **Providing [mobile access](/content/mobile-cmms/index.html)** — technicians can respond to both scheduled and condition-triggered tasks
- **Reporting on [KPIs](/content/blog/maintenance-kpis/index.html)** — measure the effectiveness of both approaches

## Conclusion

Time-based and condition-based maintenance are not competing strategies — they are complementary.

TBM provides a solid foundation for maintenance management. CBM adds precision and real-time visibility for critical assets.

The most effective organisations use both — applying the right strategy to the right asset based on criticality, cost, and operational impact.

### How Smartspanner Helps

Smartspanner provides a simple, powerful [CMMS platform](/content/cmms-software/index.html) to help your team manage maintenance more effectively — with [preventive maintenance](/content/preventative-maintenance-software/index.html), [asset management](/content/asset-management-software/index.html), and [mobile access](/content/mobile-cmms/index.html) in one system.