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Qwestrum Engineering360 · Industrial & Production · Maintenance Management

Maintenance KPIs

Maintenance KPIs track reliability, responsiveness, preventive discipline, and work-management health.
Exam tip: keep SI units consistent end-to-end, write the governing relation symbolically before substituting, and sanity-check magnitude and sign.

Key formulas & points

Skim these first — then read the full notes below.

  • Schedule compliance vs emergency work ratio
  • Maintenance cost per unit output
  • Backlog weeks = open work hours / weekly capacity

Topic details

Introduction

Without KPIs, maintenance performance remains anecdotal. Chase and Buffa highlight KPI dashboards as decision tools for staffing and budget planning.

Key relations & formulas

Formulas (Indian textbook notation)

  • MTBF=operatingtimenumberoffailuresMTBF = operating \frac{time}{number} of failures

Formulas (Indian textbook notation)

  • MTTR=totalrepairtimefailuresMTTR = total repair \frac{time}{failures}

Formulas (Indian textbook notation)

  • PMcompliance=completedPMscheduledPM×100PM compliance = completed \frac{PM}{scheduled} PM \times 100%

Notation and sign conventions

Relation 1 —
MTBF=operatingtimenumberoffailuresMTBF = operating \frac{time}{number} of failures

Formulas (Indian textbook notation)

  • MTBF=operatingtimenumberoffailuresMTBF = operating \frac{time}{number} of failures
Write this relation with symbols exactly as in Maintenance Engineering — SRK Rao before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.
Relation 2 —
MTTR=totalrepairtimefailuresMTTR = total repair \frac{time}{failures}

Formulas (Indian textbook notation)

  • MTTR=totalrepairtimefailuresMTTR = total repair \frac{time}{failures}
Write this relation with symbols exactly as in Maintenance Engineering — SRK Rao before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.
Relation 3 —
PMcompliance=completedPMscheduledPM×100PM compliance = completed \frac{PM}{scheduled} PM \times 100%

Formulas (Indian textbook notation)

  • PMcompliance=completedPMscheduledPM×100PM compliance = completed \frac{PM}{scheduled} PM \times 100%
Write this relation with symbols exactly as in Maintenance Engineering — SRK Rao before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.

Concept in depth

MTBF and MTTR capture reliability and restore speed; PM compliance and emergency ratio indicate process maturity. Backlog weeks helps workload balancing and shutdown planning. Groover-oriented plant management links KPI trends with asset lifecycle strategy.

Assumptions and validity limits

State assumptions explicitly before using any relation for maintenance kpis — steady state, uniform properties, linear elastic material, ideal gas, incompressible flow, etc., as applicable.
Wrong assumptions invalidate the entire solution even when the formula is correct. In Maintenance Management viva and GATE descriptive questions, listing valid assumptions often earns separate marks.

Step-by-step problem approach

1. Read the question and list given data with SI units (common in Maintenance Management papers).
2. Draw a neat labelled diagram where applicable — examiners in Indian universities award diagram marks even when arithmetic slips.
3. Identify which relation from this topic applies to maintenance kpis.
4. Use equation 1:
MTBF=operatingtimenumberoffailuresMTBF = operating \frac{time}{number} of failures
.
5. Use equation 2:
MTTR=totalrepairtimefailuresMTTR = total repair \frac{time}{failures}
.
6. Substitute values, compute, and verify units and sign (direction).
7. State conclusion in one line — e.g. safe/unsafe, stable/unstable, feasible/infeasible.

Applications & exam relevance

Maintenance KPIs appears in plant reliability teams. In Indian industrial curricula this topic is tested because it connects theory to RCM and spare parts strategy.
GATE and semester exams often combine maintenance kpis with earlier units — revise prerequisites before attempting mixed problems.
Industry interview panels sometimes ask: "Where did you use maintenance kpis?" — answer with a lab, mini-project, or plant visit example if possible.

Common mistakes in exams

A common mistake is reporting MTBF improvement without noting operating context changes. Another is using calendar time instead of actual operating time in numerator.

Quick revision checklist

Before attempting maintenance kpis problems, confirm you can:
1. Schedule compliance vs emergency work ratio
2. Maintenance cost per unit output
3. Backlog weeks = open work hours / weekly capacity
Revise the solved examples in Maintenance Engineering — SRK Rao and one previous-year GATE or university paper for this unit.

Worked examples

Try the problem first — open the solution when you are ready to check.

MTBF and MTTR

Problem

Machine operated 900 hours with 6 failures. Total repair time for these failures is 30 hours. Compute MTBF and MTTR.

Solution

MTBF = 900/6 = 150 hours. MTTR = 30/6 = 5 hours.

Conceptual check — Maintenance KPIs

Problem

In a Maintenance Management semester or GATE paper you are asked: "State the main assumption, the governing relation, and one practical consequence of maintenance kpis." What should a complete answer include?

📖 Standard books (India)

  • Maintenance Engineering — SRK Rao

    Read: Syllabus unit

    Reliability, RCM, and maintenance planning

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