What is Maintenance in manufacturing?

Maintenance in Manufacturing

The dictionary defines maintenance as “the work of keeping something in proper condition” or “the process of preserving a condition or situation“.

The technical meaning of maintenance involves regular & routine Cleaning, checking, servicing, repairing or replacing the parts in order to prevent the breakdown of a machine Or machine tool.

What is the need for maintenance?

In manufacturing, equipment and machines are very important resources that are constantly used for producing products. So, these must be kept in the best operating condition. Otherwise, Poor working of machines & equipment will lead to quality-related problems or there will be excessive downtime and also interruption of production if it is used in a mass production line. Hence, it is necessary to maintain the equipment in good operating conditions.

In certain cases, the equipment will be obsolete over a period of time. If a company wants to be in the same business competitively, it has to take a decision on whether to replace the equipment or to retain the old equipment by taking the cost of maintenance and operation.

Common objectionable conditions in the manufacturing shop floor

Whether the factory uses small machines or large ones,  there is no excuse for breakdowns. It is not hard to come up with this list of 16 objectionable conditions to avoid a possible break down.

  1. Metal shaving scattered all over the machine and floor.
  2. Machines so dirty that peoples avoid to touch them.
  3. Level gauges are hard to read because of dust and oil.
  4. Leaks in hydraulic and pneumatic equipment.
  5. Loose fasteners ( Nut, bolt, screws).
  6. Strange noises coming from the machine.
  7. Muddy oil in oil tanks.
  8. Machine vibrating abnormally.
  9. Abnormally hot motor.
  10. Sparking in wires.
  11. Loose V belt.
  12. Floors dirtied by puddles of oil leaked from machines.
  13. Clogged air ducts that emit dust into the room.
  14. Broken gauges and measuring instruments still being used.
  15. Cracks filled with temporary repairs like cardboard.
  16. Use of damaged spare parts.

5 Stages of Breakdown of machines

Why does the machine stop working? The simplest and direct answer is “deterioration”. From the day a machine is installed, its condition gradually deteriorates over the years of use, and sooner or later the single or combination of deteriorated/worn out parts will cause the machine to break down.

Almost every machine has symptoms of ill health before it breaks down. There are 5 stages of a machine on the path of Break down.

  1. Latent Minor Defect
  2. Apparent minor defect
  3. Performs below expectations
  4. Stop intermittently
  5. Break Down

The important thing is to recognize, where each machine is on that path.

Latent Minor Defects:  At this very first stage where it’s very hard to recognize the defect by ear or eye. But the machine’s rotating parts are operating under increasing friction and its fastened parts are getting a little looser. Only experienced maintenance peoples detect those faults at the first stage.

Apparent Minor Defects:  Now those defects at first stage become somewhat noticeable to the eye or ear. In addition, the machine may be vibrating more, making more noise, and leaking small amounts of oil, water, or air. But none of these defects are major enough to impair the machine’s functioning.

Performs below Expectations: Now Machine performs with the less desired precision. It’s hard to maintain dimensional tolerances at this stage. The machine is turning out products with widely varying quality and suddenly it needs more adjusting than it used to require. It can no longer keep up with quality standards.

Stops Intermittently: At this stage, the Machine usually demands frequent shutoffs to make adjustments and repairs. but can be started up again after making simple adjustments or repairs. its is not good for manufacturing operations as the Rate of production is much affected and breakdown time increases.

Breaks Down: At this final stage, the machine functions so poorly that it stops itself, which is to say it breaks down.Maintenance tools

Image source: http://www.rapidrepairautocenter.com

Types of Maintenance in Manufacturing

The life of most machines & equipment requires regular maintenance like appropriate lubrication on rotating components, Belts adjustment, alignment, components replacement, servicing of engine, etc. These activities provide the maximum life of a machine or equipment and prevent them from breakdown as machine breakdowns are the inevitable facts of Manufacturing.

When we let factory equipment deteriorate, sooner or later it will break down. In view of this, how can we achieve zero breakdowns? We must take measures to halt or slow equipment deterioration before it reaches the breakdown stage. So there are three maintenance activity approaches as follows:

  1. Break Down Maintenance or Reactive/ Real-time  Maintenance
  2. Preventive Maintenance
  3. Predictive Maintenance

Breakdown Maintenance Or Reactive / Real-time Maintenance

“Breakdown maintenance comprises the maintenance procedures taken in response to a breakdown.” Break down of Punches in stamping tools, Electric motor failures, Misalignment of components are examples of common realtime breakdowns and required realtime/breakdown/corrective maintenance.

This type of maintenance activity generally corrects problems for a long time ( Replacement of worn-out spares part), thus also called Corrective Maintenance.

Note: When machines do their job, they are bound to deteriorate, however, they could have been saved from breakdowns through preventive and predictive maintenance but Preventive and predictive maintenance cannot be  100% breakdown-proof for machines.

Preventive Maintenance

“Actions performed on a time or machine-run-based schedule that detect, preclude, or mitigate degradation of a component or system with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level.” Called the Preventive Maintenance.

Once a breakdown occurs, we must find the cause and make an improvement that will prevent the same kind of breakdown from occurring again. To do this, the people who are dealing with the breakdown must see it first hand,  and then make a decision about how to respond effectively to the problem.

Predictive Maintenance

Predictive maintenance can be defined as “Measurements that detect the onset of a degradation mechanism, thereby allowing causal stressors to be eliminated or controlled prior to any significant deterioration in the component physical state. Results indicate current and future functional capability”.

Difference Between Predictive and Preventive Maintenance: Basically, predictive maintenance differs from preventive maintenance by basing maintenance need on the actual condition of the machine rather than on some preset schedule. Preventive maintenance is time-based.

Activities such as changing lubricants are based on time, like calendar time or equipment run time. For example, most people change the oil in their vehicles every 3,000 to 5,000 km traveled. This is effectively basing the oil change needs on equipment run time.

No concern is given to the actual condition and performance capability of the oil. It is changed because it is time. This methodology would be analogous to a preventive maintenance task. If, on the other hand, the operator of the car discounted the vehicle run time and had the oil analyzed at some periodicity to determine its actual condition and lubrication properties, he may be able to extend the oil change until the vehicle had traveled 10,000 km. This is the fundamental difference between predictive maintenance and preventive maintenance.

3 Lessons to be remembered in Maintenance

Cleanliness:

Machine operators need to fully recognize the importance of maintaining cleanliness and make it just as much a part of their daily routine. Maintaining cleanliness is not something to be done at the odd moment between one production operation and the next. Instead, we should view it as an essential part of pre-production activities.

Benefits of cleanliness:

  • The neat and clean machine will have a higher production rate.
  • A neat and clean machine will turn out fewer defective products by bringing better quality products.
  • A neat and clean machine will cause fewer injuries as dusty and oily surfaces to cause injuries in the shop floor.
  • A neat and clean machine will bring better maintenance options as it is quite easy to understand that a dirty oil tank leakage or air leakage will harder to find out for the maintenance team.

Checking:

Maintenance should be understood as an activity designed to prevent equipment or machine from breaking down. The purpose of checking is to determine whether the equipment is about to break down. Since the operator is the one who knows best how well or poorly the machine is operating, the operator has the kind of concrete problem-consciousness needed for effective daily checking and, when necessary, inform the maintenance team.

Oiling:

We need to give each machine just the kind of oil it needs, just when it is needed, and in just the amount needed. Oiling and greasing of machines is a primary maintenance activity. It is so important that only oiling and greasing can decreased breakdowns by 25%.  Oiling and greasing of rotating or moving components reduce the friction and noises. Also, reduce Wear & tear which is good for manufacturing.

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