52 Condition cycle

Step 4 Critical assessment

The aim here is to assess the equipment production process and to agree the relative criticality of each element. This will enable priority to be allocated for the conditional appraisal, refurbishment, future asset care and improvement of those elements most likely to have an effect on overall equipment effectiveness.

The approach is to review the production process so that all members of the team understand (probably for the first time!) the mechanisms, controls, material processing and operating methods. Operators and maintainers must be involved in identifying the most critical parts of the process from their own perspective.

The important components and elements of the process, machine or equipment are identified: some typical examples are electrics, hydraulics, pneumatics, cooling systems and control systems. Each of these elements is assessed in terms of criteria such as the following:

• Safety If this component was in poor condition or failed, what would be the impact on safety due to increased risk of injury?

• Availability If this component was in poor condition or failed, what would be the impact on the availability of the equipment, including setup and the need for readjustment of equipment settings?

• Performance What impact does this component have on the cycle time or processing capacity of the equipment when it is available to run?

• Quality If this component were in poor condition or failed, what impact would it have on product quality at start-up and/or during normal production?

• Reliability What impact does the frequency with which this component fails have on the overall criticality of the equipment?

• Maintainability What impact does this component have on the ease of maintaining or repairing the equipment?

• Environment If this component was in poor condition or failed, what would be the impact on the environment due to emissions, noise, fluid spills, dust, dirt, etc.?

• Cost If this component was in poor condition or failed, what would be the impact on total cost, including repair and lost production?

• Total The sum of the rankings for each component.

The significance of each of the criteria is assessed and allocated a score according to impact on the process: 1 = no impact, 2 = some impact, 3 = significant impact.

A typical matrix form for recording process elements and criteria scores is shown in Figure 5.14. The right-hand (totals) column enables priority to be applied to those elements most affected. This is further illustrated in Figures 5.15 and 5.16.

The main outputs from the critical assessment process are that it:

• starts the teamwork building between operators and maintainers;

• results in a fuller understanding of their equipment;

• provides a checklist for the condition appraisal;

• provides a focus for the future asset care;

• highlights weaknesses regarding operability, reliability, maintainability.

The critical assessment matrix provides the basis for understanding not just the most critical components but also those which contribute to special loss areas. For example, high scores on S, M and R indicate components which have a high impact on safety, are unreliable and difficult to maintain. A score of 6 or above on these three is an accident waiting to happen.

Other useful subsets include:

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