Time Based Maintenance

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PM Element 3. Equipment Maintenance Strategy

How to start the Time Based Maintenance System?

The best way to start is putting more resources for the critical equipment or the most important equipment.

How to define the critical equipment ?

A way to do that is establish some criteria to sort the equipment in A, B, C categories.

For that it is necessary to develop some criteria related, for instance,  to SHE (Safety, Health and Environment), Quality, key brands volume production, and what impact an equipment breakdown could cause in each criteria.

Then start developing your program first for A equipment, second B equipment, and finally C equipment.

Also this prioritization can help the maintenance cost reduction, because it is possible to focus more resources for critical equipment, reduce work on non-critical equipment, and in the end keep the same result, spending less money.

Criticality Flow Chart


SHE – Safety Health & Environment

I – Influence

EX – Product Expiration Time

UR  – Utilization of Equipment

KB – Key Brands

DF – Defects

MS/AD – Minor Stoppages / Adjustments.

Q – Quality

MT –  Maintainability

Criteria for Equipment Criticality

Maintenance Strategy Applied

Step 1 :

Divide the equipment by component level

  •   Equipment
  •   System
  •   Subsystem
  •   Component

Step 2:

Determine who is responsible to perform the inspection. The idea is to identify the necessary skill, for instance operator, mechanic, electrician, contractor, supplier, etc….

Step 3:

Determine what the person is looking for during the inspection:

– Wearing, Vibration, Leak, Noise

Step 4:

How is the tradesmen or the operator going to do that?

– Visual Inspection, Touching the machine, Measuring the wearing, Functional Inspection.

Also this is the time to study if an Inspection Standard is required. An Inspection Standard is  applied for critical jobs or when a certain level of expertise is required. This standard explains the inspection step by step.

Step 5:

When is it necessary to do this inspection?

Determine the best interval weekly, monthly, quarterly, semi annually, annually.

Preventive Maintenance

After developing the inspection for the equipment it is time to develop an annual schedule for the factory. It allows you to visualize the inspections and also the adherence in this activity.

The Flowchart below describes a preventive system.


After applying the time based maintenance for some time,  identify the Mean Time Between Failure for each component.

To identify the MTBF for a component you will need to identify how many times the component has been changed either due to breakdown or preventive maintenance.

After identifying the components with the lowest MTBF, these components need to have their life cycle increased, then you will spend less hours to replace these components and spend less money with spare parts.

Use the MTBF information to improve the inspection plan. If a component has a MTBF of 180 days, and it has been inspected every week, you are looking 26 times for this component to find a problem. Is it possible to increase the time between inspections? Using this information it is possible to identify the equipment that has been over inspected.


First: Establish a Time Based Maintenance system to reduce the number of breakdowns.

Second: Use the MTBF by component to improve the system and reduce the cost.

Identify Low MTBF Component

MTBF Control by Component Matrix




After improving the useful life of critical components, update the inspection schedule.

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