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3rd Pillar of the TPM, the planned maintenance is to move from a maintenance where one suffers the failures to a maintenance where we anticipate them.

Definition

According to the standard Afnor NF en 13306 X 60-319, the ” planned maintenance” is a maintenance performed at predetermined intervals or according to prescribed criteria and intended to reduce the likelihood of failure or the degradation of the operation of a product“.

Developing a planned maintenance plan means increasing output (0 problem of Reliability, 0 breakdown) and improve the skills of maintenance technicians by increasing the availability of equipment. This implies reducing the “curative and palliative ” actions of maintenance to build a system that includes1.2 :

  • Systemic, conditional and regular predictive Maintenance to prevent failures.
  • Corrective Maintenance to reduce the risk of failure.
  • Stop maintenance to restore the machines and to refunction better as quickly as possible.
  • Supplement in continuous improvement of autonomous maintenance3.

In terms of culture, to implement the planned maintenance, it went from a “reactivity” mode (“A failure takes place, it is necessary to restart as soon as possible“, also called ” Firefighter ” mode) to a mode of proactivity (“Thereis possibility of a Failure, must act“). Thus, the planned maintenance has the issue of:

  • Extend the interval between two programmed stops.
  • Decrease the duration of the intervention.
  • Limit the severity of the degradation.
  • Master the production tool by aiming for the “ Zero failure ” and making the processes stable.
  • Reduce maintenance costs
  • Support the activities of autonomous maintenance.
  • Intervention at the most optimal and appropriate.
  • Maintain equipment in optimum conditions

Several types of planned maintenance

Systematic Maintenance

According to the standard Afnor NF EN 13306 X 60-319, this is a ” preventive maintenance performed at predetermined intervals of time or according to a defined number of units of use but without prior checking of the property “.

The frequency is based on 2 parameters:

  • a time interval: daily, weekly, monthly… it helps to prevent corrosion, fatigue and other types of damage.
  • the use of the equipment: number of products made, number of cycles… it allows to evaluate and measure the deterioration of the machine according to the use made of it.

You will find in our article on the Reliability How to determine the frequency of parts change.

Conditional Maintenance

This is a Shape of planned maintenance, also known as ” active or proactive maintenance4. According to the standard NF en 13306 X 60-319, “ conditional maintenance is based on monitoring the operation of the property and/or significant parameters of this operation incorporating the actions resulting therefrom “.

It is a maintenance which consists in monitoring the variations or degradation of the parameters that are measured on the equipment by vibration analysis, particle, ultrasound, video, functional play, thermography… 5

The peculiarity of this maintenance is to visualize the evolution of the parameters either in the spot inspection framework or in continuous.

Predictive Maintenance

The definition of Afnor NF en 13306 X 60-319 indicates that this is a ” conditional maintenance performed according to the extrapolated forecasts of the analysis and to the evaluation of significant parameters of the degradation of the property “. In other words, predictive maintenance is the implementation of conditional maintenance.

The objective of the predictive maintenance is to prevent the moment when we will have to stop the machine. This is done by putting under control the different functions of the equipment in order to intervene when one or more parameters have reached an alert threshold6.

It’s a bit maintenance “ crystal ball ” of scheduled maintenance7. The key is to identify the right parameter that will allow us to see the trend8. Predictive maintenance is established in 3 steps9 :

  1. Establish the technological methods to monitor the parameters.
  2. Diagnose the parameters and compare them between their current states and the targets.
  3. Set up the maintenance actions according to the variations.

Corrective Maintenance

According to the European standard NF EN 13306 X 60-319, ” corrective maintenance is performed after detection of a fault and intended to deliver a property in a state in which it can perform a required function “. Corrective Maintenance is a maintenance that allows the continuous improvement of the equipment. It allows these activities to feed into data for other types of maintenance.

Prioritize the deployment of scheduled maintenance

Implementing scheduled maintenance is a complex and costly process. It is necessary to do this step by step and prioritize the equipment.

Step 1: Prioritize the line/equipment

Class A

Class B

Class C

Legal

Maintenance demanded expressly by the standards or rules of the business line.

Maintenance not required by standards but only by internal recommendations.

Maintenance not required by standards or rules.

Security High risk. Average risk. Low risk.

Quality

High probability.

Low probability or easily detectable.

No chance.

Work

Equipment used 24/24.

Equipment used only on 2 teams.

Equipment used on one team.

Time

It’s a bottleneck. Its stop results in the total stoppage of production.

Its stop would impact the overall performance.

No effect on total production.

Frequency

A few failures in the last two months.

A few failures in the last six months.

The last blackout was over six months ago.

Maintenance

MTTR of about 2 hours.

MTTR between 45mn and 2hr.

MTTR less than 45mn.

Cost

The stop costs us more than 10 000 € per hour.

The stop costs us between 5 and 10 000 € per hour.

The stop costs us less than 5 000 € per hour.

Step 2: Prioritize the subset/ Part

Class A

Class B

Class C

Legal

Maintenance demanded expressly by the standards or rules of the business line.

Maintenance not required by standards but only by internal recommendations.

Maintenance not required by standards or rules.

Cost

The stop costs us more than 10 000 € per hour.

The stop costs us between 5 and 10 000 € per hour.

The stop costs us less than 5 000 € per hour.

Time

More than 90 days to get replenished.

Between 21 and 90 days.

Less than 21 days.

Maintenance

Part replaced by the manufacturer only.

Part replaced by specific organizations and a few people certified internally.

Part replaced by the maintenance staff.

Steps to implement scheduled maintenance

There are many models of planned maintenance deployment, we will retain that of the JIPM , recognized as the “ Standard ». We find a four-step implementation.

Phase 1: Reduce variability and lengthen the MTBF

This first phase aims to establish the basic conditions of the equipment without improving them (the redesign of the tools or equipment will be carried out from Phase 2). We will seek to reduce the variability and lengthen the MTBF (Mean Time Between Failure) via different actions:

  • Restore the damage left unattended.
  • Eliminate the causes that accelerate deterioration.
  • Divide the machine into a subset to control them on a regular basis.
  • Prevent recurrence of new deterioration.
  • Set up the maintenance standards (One Point Lesson…).
  • Set up an information system (CMMS: Computerized Maintenance Management System) to collect and store information maintenance: Date and time of the failure, severity of the failure, model of equipment, broken component, nature of the Failure, cause of failure, action taken, effect as a result of the action, time and number of people assigned to the outage.
  • Clean and lubricate the internal parts of the machine, part of which must be made by the operators as part of the autonomous maintenance.
  • Set up daily inspections and use control standards that use the 5 senses.
  • Make sure you have all the parts plans.
  • Set up scheduled maintenance audits.

Phase 2: Lengthen the service life of the equipment

The challenge here is to increase the service life of parts and equipment via:

  • The maintenance of the initial conditions in Phase 1.
  • The modification of the design (material, Shape, sizing…) of the tools and equipment to extend their life expectancies.
  • The elimination of sporadic failures.
  • The introduction of the standards of feedback, among others, the standards to include the machine improvements identified for the next machine purchases.

Phase 3: Implement systemic maintenance

It is through a thorough study that maintenance will be able to define the standards of systemic maintenance. Each Part has its own characteristics and fault-related behavior: which Partcan be changed in a systemic way? Which can be predicted? which require inspections? … Taking into account parameters such as costs. Thus, in this phase, it is:

  • Check that the results of the previous phases have increased the life span.
  • Understand the irregularities of failures through the five senses.
  • Identify root causes of deterioration
  • Develop a systemic maintenance plan through methodologies such as the 2 presented in the previous chapter or the RCM2.

Phase 4: Predicting the life of the equipment

The principles of predictive and conditional maintenance are introduced. From then on, we really go into anticipation of failures, where ” random ” failures become sporadic. The main actions will be:

  • Put under control the parameters related to the need for predictive and conditional maintenance.
  • Reduce maintenance Intervention times
  • Optimize system maintenance to reduce costs
  • Evaluate impact on maintenance indicators- MTBF, MTTR…-and costs, improve and deploy the planned maintenance system as a whole.

The key to Success

The key to success for scheduled maintenance is to have maintenance plans for each of the maintenance types. Maintenance plans should be based on history and failure analysis. The challenge is to start, from the outset of implementation, to set up the standards for capitalizing the data on the failures (place, date, intervention time, known cause…).

The cost of scheduled maintenance

Among other issues, the TPM approach will act on the overall costs of equipment maintenance. The diagram below highlights the fact that at the most the planned maintenance is effective at the most the cost of repair and breakage is low. The challenge is to find the optimum between the cost of preventative maintenance and the cost of repairs.

Source: M. P. Stephens (2010) – Productivity and reliability-based maintenance management

Source

1 – T. Suzuki (1994) – TPM in Process Industries

2-Japan_Institute_of_Plant_Maintenance (1997)-Autonomous Maintenance for operators

3-Japan_Institute_of_Plant_Maintenance (1996)-TPM Total Productive Maintenance Encyclopedia

4 – P. Arquès (2009)-Predictive diagnosis and machine failure. Theory-Treatment-analysis-recognition-prediction

5 – J. Leflar (2001)-Practical TPM

6 – H. Nishinaga (1999)-Construction of a System for Efficient predictive Maintenance

7 – H. R. Steinbacher, N. L. Steinbacher (1993)-TPM for America: What it Is and Why You Need it

8 – T. Wireman (1991)-Total Productive Maintenance-An American Approach

9 – H. Nishinaga (1999)-“Construction of a System for Efficient predictive Maintenance

10 – Nippon Zeon Co, PM Prize reading Digest

D. Averill (2011) – Lean Sustainability, creating safe, enduring, and profitable operation

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