Improve Easily Your Maintenance Routines
Generally speaking, maintenance aims at the following objectives:
- Maximum equipment availability
- Costs and risks reduction
However, three different types of objectives may be distinguished:
- Volume production increase: are the installations saturated? Is the market ready to buy more volume?
- Maintenance expenses reduction: is the cost price too high? Are the installations not saturated?
- Profitability of the invested capital: is the company having cash-flow problems? Is the profitability of the invested capital too weak?
The first process is about carrying out interventions, and it may be defined as follows:
Monitoring deadlines and intervention reactivity
- Carrying out corrective interventions within the timeframe of the production
- Meeting preventive intervention plannings that are easily accessible with the Calendar feature available on the Mobility Work App
- Performing accurately from the beginning (technical training, diagnosis quality, etc.)
Controlling intervention costs
Intervention costs may be categorized into two different groups:
Internal and external staff costs
- Scheduling daily/weekly interventions
- Preparing interventions (operating modes, parts, tools, safety)
- Controlling subcontractors costs and performances
Industrial supplies costs
- Ensuring good storage conditions,
- Monitoring spare parts consumption
- Controlling unit purchase price for consumed supplies
Second process is related to reliability and includes the following tasks:
Monitoring the reliability of the installations
- Identifying continuously the most detrimental equipment regarding to reliability thanks to the Analytics tool available on the CMMS Mobility Work
- Analyzing detrimental equipment and develop the content and the frequency of the preventive maintenance programs
Monitoring unreliability costs
- Identifying continuously the most expensive equipment in regards to maintenance
- Analyzing expensive equipment and develop the content and the frequency of the preventive maintenance programs
Monitoring industrial supplies stocks
- Identifying accurately the storage necessary to avoid parts to be broken and to avoid over-storage
The last process is related to life cycle management and is defined as follows:
Make sure that the maintenance teams have access to:
- Technical information
- Operating modes
- Equipment ranking based on criticality
- Preventive maintenance initial programs
- Initial stock investments according to the risks
Identifying constantly equipment that are in the end of their useful life, and controlling global possession costs:
- Production loss
- Maintenance costs
Production has to hand over manufacturing programs to the staff operating on the maintenance process:
- When will the installations operate?
- What time is the changeover scheduled?
Also, maintenance may enable technicians to schedule and to prepare interventions. Maintenance teams also have to communicate with production units on:
- The frequency of preventive interventions
- Which equipment
- For how long
All this information may be managed with Mobility Work, the industry 4.0 CMMS, which enables production units and maintenance teams to exchange information.
RCM: Reliability centered maintenance
RCM is a maintenance process focused on reliability. Is ensures a logical and structured development to programmed maintenance programs in order to obtain very high reliability levels.
Definition of critical equipment
Most plants that opted for Total Productive Maintenance (TPM) usually rank their equipment according to maintenance standards.
For instance an ABC ranking:
- Very critical equipment (A)
- Critical equipment (B)
- Less critical equipment (C)
These machines are part of one these 3 categories:
- Machines which may provoke a huge decrease in production
- Which may cause significant defects in the quality of the product
- Which may expose operators to any risks in case of failure
- Which may break down more than once every three months
Definition of the expected performances for this equipment : A distinction must be drawn between maximum and optimum performances.
FMECA may be defined as follows:
- Definition of the potential failure modes on these equipment
- Definition of the potential failure effects
- Definition and quantification of the consequences of these failures
- Probability of occurrence of these failures
- Definition of preventive actions in order to reduce or to get rid of the identified risk
The best action to implement may be to schedule (program) maintenance interventions and to monitor operations.
RBM or risk based maintenance
RBM aims at reducing maintenance expenses as close as possible to the threshold of occurrence of undesired risks. RBM also implies to master RCM perfectly first.
Scheduled maintenance includes maintenance activities which require to be carried out according to a precise program or calendar. This must be a quick-answer system. Early defects may be highlighted with two methods:
- Periodic maintenance (on a regular basis)
- Predictive maintenance (based on the analysis of the conditions of use)
Periodic maintenance (on a regular basis)
It aims at carrying out the following activities on the basis of a predefined calendar:
- Periodic control (weekly, monthly, yearly)
- Replacement of certain pieces on a regular basis
- Periodic revisions
- Periodic precision level measurement (static and dynamic)
- Oil treatment and replacement
Predictive maintenance (based on the analysis of the conditions of use)
- Estimating when the anomalies will appear, without dismantling the machine
- Enabling to check the quality of the reparations on revised machines
- Helping to estimate repair intervals
- Reducing maintenance costs by getting rid of periodic revisions
The two diagnosis methods are:
- Basic analysis: measurements are being performed with a simple vibration or overload detector to detect potential anomalies
- Every basic analysis has to be organized so that the operators will be able to carry them out themselves
- Precise diagnosis requires very sensitive tools to found out about the vibration sources, to measure them and to analyze their frequency
Repartition between preventive and corrective maintenance
There are two main maintenance processes:
- Corrective, accidental maintenance
- Preventive maintenance
Most maintenance programs are a combination of these two processes. The two major drawbacks of corrective or accidental maintenance are:
- Production disruption may be considerable
- Large security stocks may be necessary
However, when the failure is predictable, a predictive maintenance process may be more appropriate, this way is can be scheduled. Obviously, the more preventive maintenance is carried out, the fewer failures you are likely to have later. The main factors to take into account are:
- Number of machines and equipment
- Failure rate
- Average cost for the maintenance of a machine (it depends a lot on the procedures and on task distribution)
- Staff quality
- Some equipment do not apply to preventive maintenance due to the failure rate distribution
Choosing a type of maintenance depends on the organization that needs to be set up:
- Multidisciplinary or specialized teams
- Regular or team work
Generally speaking, efficiency and effectiveness are linked to programing. The down time of a machine which has just broken down can be divided into three:
- Waiting for the maintenance team
- Diagnosis time
- Repair time
Failure time reduction with equal workforce also depends on expertise. Diagnosis time can be reduced by using advice systems and by pooling expertise.Waiting time depends on the size of the intervention team and on the number of failures. There are mathematical models to determine the most optimum team.All too often, the maintenance team is busy to work on occasional failures and does not have the time to carry out complete periodic maintenance controls (revisions), so that failures reappear due to a lack of preventive measures.
Distribution between manufacturing and maintenance
The maintenance unit should be in charge of:
- Tasks that require a particular skill
- General revision in which the deterioration cannot be seen to the naked eye
- Repairs on machines that are difficult to dismantle and to reassemble
- Tasks which require special measures
- Tasks which pose a serious risk to safety
Distribution between manufacturing and maintenance is an important issue.
Operators have to develop a certain number of abilities:
- Ability to detect anomalies and to make improvements
- Ability to understand the features and the components as well as detecting the root causes of anomalies
- Ability to understand quality problems and to detect the causes.
In case of a failure, the production worker has to be able to establish a diagnosis, and to repair it in some cases. If the failure requires an intervention of the maintenance unit, the production worker may be asked to assist the maintenance staff.
The operator has a stock of color labels at his disposal to stick on the machines on which defects that he cannot fix himself have been detected. The maintenance team will remove these labels after repairing.
Three of the most important 5S are:
- Set in order
The operator may carry out some tasks:
- Oil levels, etc.
- Filter cleaning
- Detecting leaks
- Tightening untightened nuts
- Unscrewed or unadjusted covers
- Identifying visible mechanical incidents: cracks, wear, etc.
- Mechanical settings
- Voltage measurement
- Controlling detectors and microswitchs
For more information, you can also read : Autonomous Maintenance: The 5 Steps to Successful Implementation
This may incur significant expenses.
It depends on the policy (capacity, skills, or both).
Key factors for sucess
To sum up, these are the key factors to success in monitoring your maintenance:
- Size of the maintenance team
- Know-how (analyzing the root causes of failures)
- The repair shop location
- Procedures (first level, second level, etc.)
- Using working standards
- Availability of spare parts
- Selecting priorities: very critical equipment (A), critical equipment (B), less critical equipment (C)
- Some critical equipment or component may be doubled (this may incur significant expenses)