The primary purpose of an equipment maintenance plan (EMP) in a manufacturing facility is to minimize the impact of unplanned events on safety, the environment, and business profitability. The reliability tool best serving as a vehicle to achieve and sustain EMP goals is the failure modes and effects analysis (FMEA). Optimum long-term cost of ownership is typically a result of an effectively facilitated and thoroughly implemented FMEA.
Laying the Groundwork
The first step in laying the groundwork for an FMEA-based reliability improvement effort is to identify candidate equipment. The preferred method is by criticality analysis, a tool used to evaluate how equipment failures impact organizational performance in order to systematically rank plant assets for the purpose of work prioritization, material classification, preventative maintenance / predictive maintenance (PM/PdM) development, and reliability improvement initiatives.
The criticality analysis is a team effort which requires cross-functional input from Operations, Maintenance, Engineering, and Materials Management groups; and representation from the Environmental Health and Safety (EH&S) organization. This team will identify a prioritized list for EMP development.
Next, ensure that design criteria, existing maintenance tasks, operating strategies and past experiences are available for inputs to the subsequent FMEA. These are typically found in:
• Equipment Files & Drawings
• Failure Reporting and Corrective Action System (FRACAS)
• Safety Event Tracking
• Asset Utilization Database
• Computerized Maintenance Management System (CMMS)
• Reliability Near-Miss Tracking
• Process Database
After the candidate equipment is identified and front-end information is gathered, develop an FMEA project charter that clearly defines the following:
• Problem & Goal Statements
• Value Proposition
• Scope & Boundaries
• Team Members (Roles & Responsibilities)
• Project Timeline
Conduct the FMEA
FMEAs are not developed in a vacuum – they are typically conducted by a diverse team with different views and expertise of the equipment and processes under investigation. Be sure to include front-line operators and maintenance specialists on the team, and include the process owner as an ad-hoc member.
The first step in conducting the FMEA is to build a functional block diagram (FBD), which shows how different components interact with each other and which describes each component and its function. The FBD shows major components as blocks connected together by lines that indicate the relationships of components and which establish a structure around which the FMEA can be developed. The FBD should always be included with the FMEA.
Next, calculate the baseline Overall Equipment Effectiveness (OEE) and the associated financial impact for the equipment targeted for improvement. Three years of historic data are ideal but as little as one year can suffice. The FMEA project charter is updated with the baseline OEE and target OEE including the value proposition.
There are three OEE factors to consider in its calculation:
OEE = Availability x Performance x Quality
Availability = Operating Time ÷ Planned Production Time
Performance = (Total Pieces ÷ Operating Time) ÷ Ideal Run Rate
Quality = Good Pieces ÷ Total Pieces
FMEA Phase 1 Analysis – Definition and Identification
Once the team has identified the focus equipment’s functions and measured baseline reliability, the team can proceed to Phase 1 of the FMEA analysis. The elements of Phase 1 analysis are defined in terms of equipment function and functional failure, as detailed in the FBD, along with each component failure modes, root causes, effects of failure and current-state controls.
There are many types of FMEA and different versions, but we’ll use the pump system FMEA shown in Table 1:
• Equipment Function - List the functions of the equipment being studied
• Functional Failure - List the situation in which the functions would be considered lost. Most functions will have more than one loss condition
• Component - A grouping of parts into some identifiable package that will perform at least one significant function, typically an item identified in the FBD
• Potential Failure Mode(s) - The manner by which a possible failure is observed; it generally describes the way the failure occurs or its observable characteristics
• Potential Effect(s) of Failure - Describe what will happen if the failure mode occurs