Top Down-Bottom Up Approach

A systematic approach is required to establish an efficient and effective maintenance strategy. Further this system should also consider the following points :

• The operational and structural complexity of the plant.
• The relationship between production and plant engineering and its dynamic nature.
• The relationship between maintenance strategy, maintenance objective, work load and resource availability.
• Requirements, bottleneck and influencing factors.

The top down-bottom up approach accommodates all the above points for consideration. This system is briefed out here under.

Step 1: Understand the Characteristics of Plant Operation

• Construct a process flow chart.
• Understand the type of production and production policy.
• Rank the units according to their criticality.
• Identify the maintenance scheduling characteristics.
• Identify the prevailing maintenance strategy and maintenance objective.

Step 2: Establish a Maintenance Plan for each Unit

• Analyse the plant units into their 'maintenance causing items'.
• Determine the best maintenance method for each item and divide into 'on-line' and 'off-line' methods.
• Establish an off-line plan for each unit and frequency.
• Identify the corrective maintenance guidelines.

Step 3: Prepare a Maintenance Schedule for the Plant

• Prepare the list of all machines or units.
• Prepare the on-line schedules and frequency.
• Prepare the off-line schedule and frequency with the help of 2(c).
• Estimate the planned work - load for on-line and off-line schedules based on the information in 3(b) and 3(c). Also forecast the expected and unexpected unplanned work - load by the experience.
• Review the schedules once again check the accordance with actual resources available.

Step 4: Establish the Initial Policy for Spare Parts and for Reconditioning

• Identify the parts that are to be maintained as spares with the help of 2(b) and 3(a), (b) and (c).
• Consider the overall plant demand for spare parts and repairable items to determine the spares inventory policy.
• Set a reconditioning/replacement policy by calculating the replacement periods for each unit.
• Consider all the safety and quality standards to maintain.