MRO Magazine

Getting to know your equipment

In the previous issue (November 2011), we launched this series of eight articles on what is involved in achieving a world-class maintenance (WCM) department. Stage 1 explored the eight activities necessary to prepare for professional...


Machinery and Equipment Maintenance

December 1, 2011
By Peter Phillips

In the previous issue (November 2011), we launched this series of eight articles on what is involved in achieving a world-class maintenance (WCM) department. Stage 1 explored the eight activities necessary to prepare for professional maintenance. In this issue, we’ll look at Stage 2 – how to evaluate equipment and its deterioration.

There are five activities associated with Stage 2. They are:

Activity 1: Prioritization of the equipment.

Activity 2: Evaluate equipment performance, including breakdown rates, maintenance costs, current maintenance practices, etc.

Activity 3: Prepare equipment ledgers.

Activity 4: Set maintenance goals.

Activity 5: Restore equipment and maintain basic equipment conditions, and eliminate forced deterioration due to the external forces around the equipment.

Lets look at each activity in detail.

Activity 1: Prioritization of the equipment

When determining the priority of the equipment, we need to review and rank the equipment based on the two following criteria (a and b).

a) The degree of influence the piece of equipment has on other equipment, safety, cost of quality, the environment and any other key items related to your facility and its processes.

For example, laboratory equipment such as bio-safety cabinets have a high priority because of their influence on safety to laboratory personnel, as well as the environment inside and outside of the facility. (Bio-safety cabinets are used to conduct experiments where the contents inside the safety cabinet must not escape into the surrounding environment.)

We score the degree of influence using high and low value rankings:

• Affects other equipment (high 5, low 1)

• Failure affects human safety (high risk 5, no risk 1)

• Failure affects the environment (high risk 5, no risk 1)

• Affects product quality (high 5, no effect 1)

• Cost of failure in dollars, based on your cost to produce (greater than $2,000, score 5, less than $500, score 1).

b) The criticality of equipment based on its ability to stop the production line or process flow. Here, we determine how the equipment failure affects the line. We measure the criticality based on its impact on the process.

• Low-priority equipment does not impact the line or process

• Medium priority impacts the process for less than 24 hours

• High priority impacts the line for more than 24 hours

We then score the equipment criticality using these percentage rankings:

• 33.33 – Does not impact the line or process

• 66.66 – Medium impact of the line

• 99.99 – High impact of the line.

Lets try a scoring model. As an example, an air compressor that has a standby could score the following:

Degree of influence

• Affects other equipment: Low, score 2

• Failure affects human safety: No risk, score 1

• Failure affects the environment: No risk, score 1

• Affects product quality: No effect, score 1

• Cost of failure in dollars: Less than $500 – score 1

• Score subtotal = 6. The equipment criticality is 33.33, so the total score is 6 × 33.33 = 199.98.

Lets compare this is to a piece of processing equipment in a manufacturing line.

Degree of influence

• Affects other equipment: Mid, score 4

• Failure affects human safety: No risk, score 1

• Failure affects the environment: Some risk, score 3 (defect products go to a landfill)

• Affects product quality: High, score 5

• Cost of failure in dollars: Greater than $2,000, score 5

• Score subtotal = 18. The equipment criticality is 99.99, so the total score is 18 × 99.99 = 1,799.92.

Once all your equipment has been scored, a simple method is used to determine the equipment’s priority. The lowest 20% score Priority 4; 20%-80% score Priority 3; 80%-95% score Priority 2; and 95%-100% score Priority 1.

Activity 2: Evaluation of equipment performance

If there is basic maintenance being performed by operators, review the type and quality of the work they perform.

Review the current performance of the equipment; Number of equipment failures; Frequency of failures; Severity of failures and minor stops; MTBF (mean time between failures); Maintenance cost of selected equipment; Breakdown cost, material and labour; MTTR (mean time to repair); Current maintenance practices; Duration and frequency of maintenance; Type of maintenance, PMs, rebuilds; Percentage of PMs completed; Percentage of past-due PMs; Types of maintenance (corrective, PM, safety, quality or emergency breakdowns); and Backlog of maintenance work.

These findings will help us set maintenance goals in Activity 4.

Here are some ways to improve your MTBFs and MTTRs.

How can we lengthen MTBF?

• Maintain basic conditions by inspecting, cleaning, tightening and lubricating.

• Restore deterioration by replacing worn parts.

• Develop corrective action and repairs to prevent problems from recurring.

• Operate the equipment properly.

How can we lengthen MTTR?

• Raise maintenance personnel skills and knowledge.

• Improve spare parts management.

• Improve hard-to-access equipment and components.

• Apply 5S methods to work areas and workshops.

Activity 3: Prepare equipment ledgers

• Identity equipment subassemblies

• Prepare detailed information on all components

• Select appropriate maintenance activities for each piece of equipment and its components

• Prepare a lubrication map and frequency schedules

• Document all safety procedures, such as lock and tag.

By preparing equipment ledgers and breaking equipment down into its components, maintenance personnel become intimately familiar with the equipment. This exercise promotes a strong understanding and knowledge of the equipment, which is something that will help the maintenance person repair and maintain the equipment.

Every ledger also identifies the spare parts/material list for each piece of equipment. Parts can be stocked or vendors can be identified to purchase the parts when necessary.

After the ledgers are completed, maintenance activities such as preventive maintenance, overhauls, calibrations, etc., can be developed. Lubrication maps and procedures can be developed to ensure proper lubrication methods and frequencies are applied to the equipment.

 

Activity 4: Set maintenance goals

Now that we have completed the first three activities of Stage 2, we can set some maintenance goals. Based in the priority of the equipment and its current performance, maintenance goals to improve its performance and reliability can be established. Choose equipment where your improvement efforts can make the most significant change.

Believe me, these improvements will be noticed. You will gain support for your efforts and get lots of encouragement to continue.

Activity 5: Restore equipment

Finally we reach the fifth activity of this stage, restoring equipment to its
basic condition and eliminating forces that contribute to the deterioration of the equipment.

When equipment has been neglected, deterioration tends to get worse over time and spreads throughout the work area. This generally leads to a huge increase in failures.

For example, a simple unchecked problem, such as a loose bolt, can cause vibrations that gradually increase, causing other bolts to come loose. This eventually results in an equipment failure.

There are two types of deterioration, natural and accelerated. Natural deterioration is simply the normal wear and tear that occurs in spite of our efforts to use the equipment properly and to carry out scheduled maintenance. Accelerated deterioration is caused by other factors, such as the neglect of basic maintenance like essential lubrication, cleaning and inspecting.

To prevent accelerated deterioration, some basics steps need to be followed:

• Restore equipment to its base condition, replace worn parts, tighten loose fasteners, clean and lubricate.

• Develop inspection procedures to address these basic maintenance activities.

• Develop detailed preventive maintenance instructions and frequencies that will identify the equipment condition so problems found during the PM can be corrected.

• Conduct root cause analysis on chronic problems and develop corrective actions to eliminate or reduce the cause.

The goal here is to control or reduce deterioration to a level where the equipment becomes reliable and produces defect-free products.

This stage is all about a true and sincere evaluation of your equipment and your maintenance practices. You need to know what equipment to focus your maintenance efforts on first, by developing an equipment priority list. You need to know what makes the equipment tick; you’ll learn this through the equipment ledger.

You need to evaluate equipment performance so you can set goals to improve reliability and quality. If you are having trouble maintaining basic conditions, then you need to revamp your maintenance programs to get the equipment in the best condition it can be (like the used-car dealers say, in ‘like-new condition’).

There is an immense about of work to do here but the skills and the knowledge you will gain about your equipment are priceless. The attitudes of your maintenance people will improve because they will have been given the time to use their expertise to make the equipment work better. After all, this is what they train for and why you hired them in the first place.

MRO

Peter Phillips of Trailwalk Holdings, a Canadian CMMS consulting and training company, can be reached at 902-798-3601 or by e-mail at peter@trailwalk.ca.