MAINTENANCE ENGINEERING ME6012

1. MAINTENANCE ENGINEERING ME6012 By Godwin Pithalis.N.E.

2. UNIT I PRINCIPLES AND PRACTICES OF MAINTENANCE PLANNING • Basic Principles of maintenance planning – Objectives and principles of planned maintenance activity – Importance and benefits of sound Maintenance systems – Reliability and machine availability – MTBF, MTTR and MWT – Factors of availability – Maintenance organization – Maintenance economics.

3. Maintenance • Maintenance is the routine and reccuring process of keeping a machine or asset in its normal working condition so that it can deliver the excepted performance or service without any loss or damage. • The responsibility of maintenance function should be to ensure that the production equipment/facilities are available for the use of maximum time at minimum cost within stipulated time period. In other words, maintenance refers to the work that is required to be done to keep equipment in a working condition such that it can be utilized to its full designed capacity and efficiency for maximum amount of time. • Maintenance Engineering is the activity of applying engineering concepts to the optimization of equipment, procedure and departmental budgets to achieve better maintainability, reliability and availability of equipment.

4. Types of Maintenance • 1) Breakdown Maintenance • It is done after the equipment fails. • 2) Preventive maintenance • It is done periodically and it prevents the machine from failure. Need for Maintenance • To keep the machine _t and ready to use. • To increase the life of the machine and hence the durability increases. • To maintain accuracy. • To ensure the Maximum utilisation of the machine.

5. Principles of Maintenance Planning • Maintenance principles are followed in a system to guide the staff to work efficiently and effectively to achieve the overall objectives of the maintenance system. • i) Plant Management in Maintenance work: The main role of the maintenance function is to provide safe and effective operation of the equipment to achieve the designed targets on time with economic usage of resources. • ii) Production and Maintenance Objectives: The plant is driven by the production targets. The objective of these maintenance function is to support these targets.

6. Principles of planning: • Improvement of the quality of equipment and components through improved design and tighter manufacturing standards. • Maintenance activity: • Set of actions performed in the product development process Types of planning: • Single cycle plan • Time bases • Performance bases • Strategy planetary problem

7. Objectives of planned maintenance activity • Analysis of repetitive equipment failures. • Estimation of maintenance costs • Evaluation of alternatives. • Forecasting of spare parts. • Assessing the needs for equipment replacements and establish replacement programs when due application of sheduling and project management principles to replacement programs. • Assessing required maintenance tools and skills required for ef_cient maintenance of equipment. • Assessing required skills for maintenance personnel. • Reviewing personnel transfers to and from maintenance organizations • Assessing and reporting safety hazards associated with maintenance of equipment.

8. Reliablity • Reliability is defined as the satisfactory performance of a machine or a component for a specified period under specified working conditions. • The idea that an item is _t for a purpose with respect to time. • Items that do not fail in use are reliable and Items that do fail in use are not reliable. • The capacity of a designed, produced or maintained item to perform as required over time. • The resistance to failure of an item over time.

9. Contd.Reliablity • A Reliability Program Plan may also be used to evaluate and improve Availability of a system by the strategy on focusing on increasing testability & • maintainability and not on reliability. • Improving maintainability is generally easier than reliability. Maintainability estimates (Repair rates) are also generally more accurate. • However, because the uncertainties in the reliability estimates are in most cases very large, it is likely to dominate the availability (prediction • uncertainty) problem; even in the case maintainability levels are very high. • When reliability is not under control more complicated issues may arise, like manpower (maintainers / customer service capability) shortage, spare part availability, logistic delays, lack of repair facilities, extensive retro-_t and complex con_guration management costs and others. • The problem of unreliability may be increased also due to the "Domino effect" of maintenance induced failures after repairs. • Only focusing on maintainability is therefore not enough. If failures are prevented, none of the others are of any importance and therefore reliability is generally regarded as the most important part of availability

10. Availability • Availability deals with the duration of up-time for operations and is a measure of how often the system is alive and well. It is expressed as (up-time)/(up-time • + downtime) • The main factors in戊uencing Availability are • 1) increasing time to failure, • 2) decreasing downtime due to repairs or scheduled maintenance, • 3) accomplishing items 1 and 2 in a cost effective manner. • When availabilityincreases, the capacity of making money increases because the equipment is in service for more time. • The different types of availability are . • Inherent availability, as seen by maintenance personnel, (excludes preventive maintenance outages, supply delays, and administrative delays) • Ai = MTBF/(MTBF + MTTR) • Achieved availability, as seen by the maintenance department, (includes both corrective and preventive maintenance delays) • Aa = MTBM/(MTBM + MAMT) • Where MTBM is mean time between maintenance actions and MAMT is the mean active maintenance time. • Operational availability, as seen by the user • Ao = MTBM/(MTBM + MDT)

11. importance and bene_ts of sound Maintenance systems • IMinimizationof down time • Life of equipment • Safety and smooth operation • Backup Supply • Increases reliability of the system. • Working environment pro_t • It Provide adequate back up supply.

12. Maintenance Organisation • Maintenance Organisation plays a vital role in keeping the machineries _t to use. Maintenance organisation plans and executes the entire activities related to • maintenance. • The maintenance organization’s structure is determined after planning the maintenance capacity. • The main issues that must be addressed when forming the maintenance organization’s structure are: • capacity planning, • centralization vs decentralization and • in-house vs outsourcing • Maintenance capacity planning determines the required resources for maintenance including the required equipments, tools and space to execute the • maintenance load ef_ciently and meet the objectives of the maintenance department.

13. The maintenance cost is comprised of two factors: • (i) Fixed cost: This includes the cost of support facilities including the maintenance staff. • (ii) Variable cost: This includes the consumption of spare parts, replacement of components and cost other facilities requirements of maintenance. • Maintenance budget • The maintenance budget is used to set aside certain amount of money to meet the expenditures incurred in achieving the objectives of maintenance. • Types of maintenance budget. • (i) Appropriation Budget: Budget used to allocate money for each activity independently. • (ii) Fixed Budget: Fixed used to allocate money for a speci􁜥ed period of time. • (iii)Variable Budget: Dynamic allocation of expenditure based on maintenance requirements and activities.