The Four Dimensions of Maintenance
Published by : Industrial Automation
Shacheendra Bapat proposes the theory of Four Dimensions of Maintenance that will help Maintenance Managers.
Maintenance activity is one of the most important yet the most neglected activity in a manufacturing setup. The Maintenance function is considered as a Non-productive function because nothing is really ‘Produced’ while performing the activity, which will really generate revenue for an organisation. Not many Plant Managers or Operations Managers are pragmatic enough to understand the importance of a strong Maintenance Set up. While facing apathy from the management, a Maintenance manager not only has to carry out the intended activities, so as to keep the machines and equipment running, he is also required to fulfil the requirements of ISO 9001 and ISO 14001 and has to demonstrate his commitment towards Energy Management and Cost reduction and/or saving initiatives. Every breakdown is unique, that makes attending the breakdown a highly non-standardised activity. This not only makes the activity highly hazardous, it also makes it extremely stressful. Breakdowns cause severe impact on production and the maintenance team often works for extra hours or on weekly off days. These all factors make the life of a Maintenance manager extremely miserable.
As a Maintenance Manager myself, I have always believed that, while the managements expect a high Mean Time Between Failures (the MTBF), a Maintenance Manager must first focus on reducing the Mean Time To Repair (the MTTR). The life of a Maintenance Manager becomes easy if the MTTR is reduced significantly and it also gives him time to focus on the improvement activities. I herewith propose the theory of Four Dimensions of Maintenance that will help a Maintenance Manager to not only reduce the MTTR, it will help him strengthen the Maintenance processes that he has to follow and focus on cost saving initiatives. So what are these Four Dimensions? Let us discuss these four Dimensions one by one.
1. Trained Manpower
Given the nature of work, Trained Manpower must be considered as the biggest asset of Maintenance Function. A machine or equipment is made out of different circuits other than the main operating mechanism. It consists of Electrical Circuit, Mechanics, Hydraulic Circuit and Pneumatic Circuit depending upon the application and process. Gone are the days when we used to have different people to handle different functions like Mechanical Maintenance or Electrical Maintenance. While accepting expertise and educational qualification for an individual, a maintenance team member must learn all the aspects of maintenance. A mechanical setup cannot function without electricity or automation, and, electricity and automation are worthless if mechanical systems do not exist. In view of this, all the members must have a basic understanding of all these aspects.
As one keeps on working on a machine while attending breakdowns or carrying out preventive maintenance, he acquires significant knowledge. But this process is lengthy. An informal training, conducted not in a classroom, but on the machine itself, works wonders. The training can consist of the functionality of various parts of the machine, layout of and components installed inside the control panel, navigation on the HMI, cable routing, locations of energy isolating devices, quality and process parameters under control, basic machine operation parameters, lubrication points, etc.
Formal classroom training can be given on the topics like Maintenance Safety, working of electrical components, PLC programming, VFD Fundamental, Types of bearing and their uses, Predictive Maintenance Techniques and many more. Training needs must be identified before
the beginning of a new year. A training plan for individual members for the year should be made from the findings of the identified training. This plan not only helps in having an adequately trained manpower, it also fulfills the ISO 9001 requirement automatically. An appropriately trained manpower helps reducing the MTTR significantly.
2. Accurate Documentation
This is unfortunately the most neglected dimension of Maintenance function. A maintenance manager must ensure that appropriate documentation is available for every equipment that is under operation in the plant. This includes, but is not limited to, the machine operation manual, troubleshooting guide, electrical circuit, hydraulic circuit, pneumatic circuit, PLC ladder diagram, HMI application program, VFD parameters, fixture drawings and spare parts list. While it is easy to have soft copies of all these documents in a laptop, the team must have the hard copies of all the circuits available at the machine location.
Troubleshooting a problem without referring the circuits is like searching a needle in the big heap of grass. The maintenance manager must conduct a weekly audit to ensure that all the relevant documents are available for all the machines at their intended locations. I have spent many unnecessary hours on finding a root cause just because appropriate documentation was not available. This is a situation that cannot have any excuses. The MTTR can be significantly reduced if the correct documentation is available at the correct place at the correct time. Good companies demand three sets of machine documentation in their Statement of Requirement at the time of purchasing a machine. One set should be kept near the machine itself. The second set should be kept in the Maintenance area. The third set should be kept in what is called as the
Document Control Room where the entry of personnel must be restricted and the entry and exit of document into and from the room must be recorded.
3. Adequate Spare Parts
Here, the term adequate means what is required and how much is required. Mind you, at times, a small O-Ring of 6 mm diameter can stop an HMC. In view of this, planning of spares becomes a critical activity for a Maintenance manager. While making a spare parts list, following three items are needed to be considered:
1. Recommendation by the manufacturer
2. Past experience of the maintenance team, and
3. Numbers of an item (For example, a 12 mm PNP NO Proximity switch) installed in the entire plant.
While the first two items help in identifying which items to procure, the third item helps us in deciding the minimum quantity of that item to be procured and possessed.
It is also important for the Maintenance Manager to decide how critical a spare part is. Generally a spare is categorised in three types. Critical, semi-critical and not critical. An item becomes critical if its failure completely stops the machine operation. For example, the failure of a PLC CPU card or a 24 VDC power supply can stop the machine. So these items must be identified as critical spares. The second item that makes a part critical, is the lead time for its procurement. While most of the global manufacturers have their production facilities or warehouses now in India, it sometimes may take weeks for the part to arrive after an order is placed. The third thing to be kept in mind is the cost of the part itself. A judicious decision should be taken to avoid heavy expenditure on procuring a part and keeping it in the inventory unnecessarily. For example, a high power electric motor, even if imported, works efficiently for years and there is no need to keep its spare. Semi-critical spares are those whose failures can stop the machine for a
small time but can be repaired and installed in some hours. For example, certain bearings can be serviced in-house or a 12 mm proximity switch can be temporarily replaced by an 8 mm proximity switch with appropriate mounting modification. Almost all of the hardware is not so a critical items and can be procured on a short notice from local suppliers or hardware shops.
If an organisation has multiple plants, then high cost spares can be shared between two plants, suitably. The spare parts should be numbered appropriately and must be stored in a locked area.High level of 5S must be maintained in the stores to find the right part immediately, to reduce the MTTR. Minimum quantity of stock for a spare, if decided, helps in placing a new purchase order such that the part can be procured before the quantity becomes zero.
4. Correct Tools
It is extremely important to have the set of correct tools with the maintenance team. I have seen our engineers struggling to open an assembly because they did not have a circlip pliers or a screw driver that was not matching the head of a bolt. Some manufacturers purposefully use bolts with heads such that only trained personnel can open the assembly. In view of this, the Maintenance Manager must identify and procure appropriate tools for his team. Every member of the team must have his own tool box and a set of common tools in his possession at all times. Open spanner set, ring spanner set, screw driver set, nose plyer, cutting plyer, Allen Key set, hammer and chisel are some of the most basic minimum tools that a member should have. If compared, then the cost of these tools together is far too low that the cost incurred due to line stoppages. Increase in the MTTR just because of the absence of certain tools must not be tolerated.
Some special tools like a bearing puller, lubrication kit, oil loading pump, soldering iron, vibro pen, IR gun, etc., can be common for the team. It is highly recommended that if a plant is running in shifts, then every shift must have a good quality Clamp meter. Having all the correct tools helps in reducing the MTTR to a great extent. The Maintenance Manager must conduct a periodic audit to check if the members have all the issued tools in their possession and that all the tools are in good condition. He also should ensure that a tester is not being used to open a control panel or that a nose plyer or cutting plyer is not being used to open a Hex head bolt. Only the correct tool must be used for the assembly or dis-assembly. Use of incorrect tool can cause severe injury or may cause equipment damage.
Shacheendra Bapat, graduate in Electronics and Telecommunication engineering, is an Automotive and Manufacturing Industry professional having more than 26 years of experience in operation and Maintenance of Flexible Manufacturing System, HMCs, VMCs, SPMs, welding machines, paint shop equipment and conveyors, with several MNC and large Indian engineering companies. A Technical Trainer for Industrial Automation, Electrical Safe Work Practices, Maintenance Safety, Chemical Safety, Predictive and Preventive Maintenance, etc., Shacheendra is also a Certified Lead Auditor for QMS ISO 9001:2008, Certified Internal Auditor for EMS ISO 14001:2004 and Certified Project Management Associate IPMA Level D. He has worked with Hindustan Motors Ltd, Eicher Motors Ltd, General Motors Ltd and Bosch Rexroth India Ltd.