Lesson 7 – Maintenance strategies

In this lesson, we will explore various maintenance strategies and systems, which are essential for ensuring the efficient operation and longevity of machinery and equipment.

Understanding Maintenance Strategies

  • Machine maintenance, also known as product aftercare or servicing, comes in various forms aimed at preserving the operational condition of products.
  • Choosing the right maintenance strategy involves considering market demand, market penetration, operator needs, equipment requirements, design principles, spare parts availability, and environmental factors.

Implementing Maintenance Strategies

  • Maintenance strategies can be categorized as long-term, strategic, or short-term, tactical.
  • Long-term strategies include various maintenance regimes such as corrective, corrective replacement, planned preventive, preventive maintenance, and total maintenance.
  • Short-term strategies encompass immediate solutions for unexpected issues.

Maintenance Systems

  • Different maintenance systems have evolved to address the diverse nature of machinery failures and repairability.
  • Various maintenance systems are selected based on economic considerations, including:
    • On-demand maintenance and repair (“fire-fighting”).
    • Planned preventive maintenance (PPM), either time-based or performance-based.
    • Maintenance based on technical condition testing (diagnostics).
    • Total Productive Maintenance (TPM).
    • Reliability-Centered Maintenance (RCM).

Maintenance and Repair on an As-Needed Basis or as Replacement for a Defect

  • In this system, repairs occur only after a failure has happened.
  • Failed components or main parts are repaired or replaced when needed.
  • Regular care and lubrication are essential.
  • Advantages include maximum utilization of parts, but disadvantages include unplanned downtime and the need for a significant spare parts inventory.

Planned Preventive Maintenance (PPM)

  • PPM is a widely used maintenance system focused on preventing faults and unforeseen breakdowns.
  • Regular inspections and repairs are carried out according to a predefined maintenance schedule.
  • This system is prevalent in various industries, promoting operational reliability through planned inspections and repairs.

Preventive Maintenance Based on Technical Condition Testing (Diagnostics)

  • PMM relies on component wear analysis and logic.
  • However, it may not provide a precise answer due to factors like quality variations, operating conditions, and uncertainties.
  • To maintain equipment in a fit state for use, periodic or continuous technical condition tests are employed during operation.

Total Productive Maintenance (TPM)

  • TPM, rooted in Japanese industry, engages all employees in preventive maintenance through small group activities.
  • Operators take responsibility for routine machine maintenance.
  • TPM includes steps such as improving equipment utilization, autonomous maintenance, planned maintenance, training programs, and designing reliable machinery.

Establishing a Maintenance Cycle

  • Machinery gradually loses usefulness during its service life until failure.
  • Failures are influenced by operating conditions, time of use, and performance.
  • To reduce breakdowns and downtime, a well-organized prevention strategy is necessary.
  • A cycle schedule determines the intervals for inspections and repairs.
  • Cycle schedules consider maintenance frequency, inspection and repair sequence, work types, and parameters (time, distance, etc.).
  • Various methods, including wear analysis and economic calculations, are used to determine cycle times.
  • Interventions are planned to prevent expected failures, based on operational, maintenance, and repair experience.
  • Machine failure modes are often stochastic due to technical variations, material inconsistencies, manufacturing inaccuracies, and stress variations.


  • Maintenance strategies are essential for preserving the operational condition of machinery and equipment.
  • The choice of maintenance strategy depends on multiple factors, including market demand and equipment characteristics.
  • Long-term and short-term maintenance systems cater to different needs.
  • Preventive maintenance, based on both schedule and diagnostics, helps prevent unplanned breakdowns.
  • Total Productive Maintenance involves all employees in machinery care.
  • Establishing a maintenance cycle is crucial for maintaining equipment reliability and minimizing downtime.

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