Autonomous maintenance (AM) is performed by the operators and not by dedicated maintenance technicians. It is a crucial component of Total Productive Maintenance (TPM). The core idea of autonomous maintenance is to provide the operators with more responsibility and allow them to carry out basic preventive maintenance tasks.Total Productive Maintenance (TPM) was developed by Japanese companies, extending the existing concept of Total Quality Control (TQC) with the principles of preventive and predictive maintenance programs. There are numerous examples that have been published demonstrating the impact Operator related maintenance have had in improving throughput time, uptime and quality – usually seen as OEE.
With conventional maintenance programs, a machine or a section of equipment can run until it fails or reaches a preventive maintenance/condition based date. The maintenance department is then responsible for handling/fixing it. In contrast, autonomous maintenance allows machine operators to carry out simple maintenance work (lubrication, safety checks, fixture and cover security tightening/securing, cleaning and inspection) to act as “first-line” maintenance personnel in preventing breakdowns and reacting faster if a certain failure has been detected using the “eyes and ears” of seeing and listening to the motion, ‘rhythm’ of the machine.
Since TPM gives operators much more responsibilities, planned (kaizen) dedicated training is required as well as some modifications on the machines to ease operations of cleaning and maintenance. This will significantly increase the operators’ skills level and helps them better understand how to maintain and even improve the equipment.
What Actions Are Expected from an Operator Performing Autonomous Maintenance?
Autonomous maintenance requires operators to develop and master certain skills:
- Detect abnormalities and contribute to countermeasures to reduce problems;
- Understand the functions and the components of the machines and detect the causes of abnormalities;
- Recognize possible quality issues and identify their causes.
The machine operator should be able through familiarization with operating the equipment to provide fast and reliable initial diagnosis and troubleshoot in a certain number of failure cases.
The best way to transfer knowledge of how to manage this continuous learning experience is through brief one-point learning sessions and over time an entire methodical implementation program.
5S - The Starting Point for Operator Based or Autonomous Maintenance
The main objective of 5S is to create a culture or mindset of discipline and
orderliness, while the whole work area is cleaned and organized. Autonomous maintenance, on the other hand, aims to ensure that operators clean and inspect their equipment to prevent deterioration and failures.
It should be clearly understood that the two initiatives are very different. The area of overlap is where equipment-related problems need to be fixed (e.g. oil leaks or product spillage) in order to keep the area clean. This is normally done as part of 5S without any transfer of maintenance responsibilities to operators. On the other hand, deep cleaning and tagging of the equipment is the first step in a long process of establishing maintenance skills and responsibility among operators.
It is very important to first establish general cleanliness, tidiness and discipline in the work area through the implementation of 5S, before introducing autonomous maintenance. 5S often naturally leads into autonomous maintenance as a seamless process, as shown below. While autonomous maintenance is implemented in a pilot area, 5S should be rolled out across the organization as soon as possible, to ensure that everyone is involved and to create a general culture of discipline throughout the organization.
1 - Initial Cleaning and Inspection
The initial cleaning of the machines is essential for high-quality maintenance. It is usually performed by all involved members of the production, maintenance and engineering team and includes the thoroughly cleaning of the equipment and surroundings. The purpose is to ensure that the machines’ performance is fully restored by identifying and eliminating all signs of deterioration.
- Leak detection;
- Control of loosened bolts;
- Detection of oil or transmission leaks from gaskets, oil spray from lubrication systems, cutting oil leaking from pipe joints, blocked drainage points;
- Correction of defective items;
- Removal of process waste and product from the air intakes, lubrication points of motors/gearboxes, fans, compressors.
- Removal of dust and dirt on operating panels, inspection and safety covers;
- Loose covers on electrical panels allowing dust/contamination of relays and circuit breakers, clogged air filters non-working electrical cooling fans
- Prevention of fire in the waste and dust accumulated in inaccessible places;
- Faster jig and die/tooling changeover and better precision adjustments capability when change-overs occur on production lines.
The process and the results can be written down in a SOP and uploaded to the CMMS/Production SOP. This would ease the traceability of the detected faults. Furthermore, next time when performing initial cleaning, the operator can directly call-up the information and simply follow the steps.
2 - Eliminating Contamination for Maintenance
After the initial cleaning has been performed and the equipment has been restored again, it is very important to make sure that it doesn’t deteriorate again. This happens by improving accessibility for cleaning and maintenance. This is important. If the area where contamination builds-up can’t be reached then the continued operator maintenance cannot be carried out. Standards must also be generated for ensuring machine lock-out when access to certain areas is required where safety is the overriding criteria.
At this point, the machine operators can be given the freedom to control the root causes of contamination directly at source, especially given the fact that they know the machine better and were the ones who performed the initial cleaning.
This step also considers all possible safety issues that could happen during autonomous maintenance. Cleaning a running machine is quite dangerous and the shift changing of operators only increases the difficulties.
The maintenance leader should take into account the following possible solutions:
- Maintain cleaning standards. The most serious problems cannot be repaired immediately and may request the extended shutdown of the machine. Other detected issues such as leaks or damaged parts can be fixed.
- Achieving lasting cleanliness by avoiding soiling. The main causes for machine soiling should be eliminated gradually. The common solutions include high-quality sealing and covers. However, some causes for contamination may request more serious investment as dust extractors or sediment pumps.
- Promoting cleanliness, when stressing the topic during inspection operations and machine maintenance.
- Encouraging operators to keep the workplace in order. Very often, fixing a problem is delayed because of a missing specific machine tool.
- Operators should be shown how to facilitate the planned inspections by gradually eliminating any inaccessible zones.
3 - Develop Standards for Cleaning, Lubrication and Inspection
The establishment of standards for operations of cleaning, inspection and lubrication starts from the current maintenance documentation and follows the suggested lubrication and inspection schedule. This is the step, which can be individually ‘tailored’ to the operators of each machine. In this phase, the core team develops its own standards showing the items to be cleaned and/or lubricated, the methods to be used and the responsibilities to be assigned.
In this case, two complementary methods should be followed:
- With non-critical machines, operators can be trained in-house to follow the established general standards and then given the opportunity to settle their own rules, led by an experienced maintenance technician.
- For critical machines, a special working group, dedicated to maintenance methods and production, can be created.
The outcome of this phase is the agreed machine standards, which are also the best evidence for the successful implementation of autonomous maintenance at a plant.
These standards are described using One Point Lessons or very visual photo illustrations where text is kept to a minimum.
4 - Inspection and Monitoring
Basic machine inspections are frequently overlooked in many manufacturing/processing plants.
This doesn’t have to be the case, since the implementation of equipment inspection is not hard to do. The machine operators can successfully perform the following simple tasks:
- Checking lubrication levels;
- Locating leaks;
- Tightening loose bolts, fittings
- Identifying possible mechanical problems such as wear, wobble, change in the sound of a moving assembly, the feel of overheating motors, appearance of cracks in moving assemblies.
- Make mechanical adjustments, check belt tension, level of air /water/hydraulic/steam pressure used by the machine, check mechanical position settings, operation of micro switches and sensors. Again, use well illustrated One Point Lessons.
5 - Finalize Standards
The last step for a successful implementation of autonomous maintenance is to finalize all provisional standards and establish a process for autonomous maintenance.
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