Maintenance

• Corrective Maintenance

  Used only after a failure. Includes all unscheduled maintenance actions performed, as a result of system/product failure. To restore the system to a specified condition.
• Five major categories of Corrective maintenance

  • Fail-repair
  • Salvage
  • Rebuild
  • Overhaul
  • Servicing

  
• Sequential steps for performing corrective maintenance

  1. Recognition of existence of failure

  2. Localizing the failure within the system to a specific item/equipment

  3. Diagnosing within the item/equipment to identify specific failed part/component

  4. Replacing or repairing failed item/part/component

  5. Checking out and returning the system to service
• Characteristics of Corrective Maintenance

  • A correction maintenance activity is generally planned
  • A planned or unplanned corrective maintenance operation depends on the nature of breakdown and type of equipment/machine
  • The maintenance work is taken up after the occurrence of a breakdown and with some permissible time lag
  • Breakdown maintenance should not be very serious in nature as far as production losses, down time, loss of human life etc. are concerned
  • Breakdown of individual equipment should not effect considerably the overall production loss

  
• Typical Causes of Equipment Breakdown

  • Failure to replace worn out components/parts
  • Lack of lubrication
  • Neglected cooling arrangement/system
  • Indifference towards minor faults
  • External factors such as wrong fuel, too low or too high line voltage etc.
  • Indifference towards equipment vibrations, unusual sounds coming out of the rotating parts and equipment getting too much heated up
• Corrective Maintenance is justifiable in these particular circumstances
• Typical example of Corrective Maintenance

  • Broken plate glass doors and windows
  • Malfunction of entrance doors
  • Damaged washroom fixtures
  • Blocked sewers and drains
  • Broken fan belts
  • Malfunction of an elevator
  • Electrical overloads
  • Frozen water lines
  • Burned out ballast
  • Changing light bulbs when blown
• Level I Corrective Maintenance


  Includes simple maintenance activities that are essential to the operations, and are carried out on easily and safely accessible elements thanks to machine-integrated support equipment. This type of operations may be carried out by the production operator and scheduled.
• Examples of Level I Corrective Maintenance

  • Light bulb replacement
  • Common locksmith operations, scrapers (removing paints, dirt or unwanted matters of a surface)
  • Setting and replacement of wear or outdated parts, on simple and accessible components
• Level II Corrective Maintenance


  Includes operations which require complex procedures. A qualified technician with detailed procedures may carry out this type of maintenance operations.
• Examples of Level II Corrective Maintenance

  • Diagnosis
  • Repairing a refrigerant leak (cooling unit)
  • Standard exchange replacement on components by general technical expertise, with no common or specialized support means (controller card, cylinder, pump, engine, gear, bearing, etc.)
  • Repairing means of production using measuring tools and individual diagnosis

  
• Level III Corrective Maintenance

  Dedicated to operations whose procedures imply particular techniques or technologies. A qualified technician or team with any general or special maintenance instructions may carry out this type of maintenance operations.

  
• Examples of Level III Corrective Maintenance

  • Compressor valves replacement
  • Cable head replacement (alternative low voltage)
  • Pump revision in a specialized repair shop after a preventive discard
  • Repairing means of production using measuring tools or collective and/or highly complex diagnoses (portable programming, numerical control regulation system, regulators, etc.)
• Level IV Corrective Maintenance

  Consists of operations whose procedures imply a particular know-how, and require special techniques, technologies or processes. By definition, this type of maintenance operations (renovation, reconstruction, etc.) may be carried out by the manufacturer or by a specialized company with support equipment defined by the manufacturer that is close to the manufacturing of the concerned equipment.

  
• Examples of Level IV Corrective Maintenance

  • General revisions with complete machine dismantling
  • Dimensional and geometrical recovery
  • Manufacturer major repairs and equipment reconditioning
  • Wear or outdated goods replacement

  
• Level V Corrective Maintenance

  Dedicated to interventions which require simple procedures. A qualified worker with detailed procedures may carry out this type of operations. An employee is said to be qualified after having taken a training which allows him to work safely on a good that may carry potential risks; then he is considered to be skilled for this task, in view of his knowledge and capabilities.
• Examples of Level V Corrective Maintenance

  • Standard exchange replacement: fuses, belts, air filters, etc.
  • Braids (a complex structure or pattern formed by interlacing two or more strands of flexible material such as textile yarns, wire,), stuffing box, etc. replacement
  • Standard exchange replacements on individual wear or outdated components (rail, slide rail, roller, rolls, chains, fuses, belting, etc.)
• Illustrative examples of corrective maintenance

  • Emergency Repair
  • Service Outages
  • Repair
  • Performance
  • Quality

  
• Preventive Maintenance (PM)


  Includes all scheduled maintenance actions performed to retain a system or product in a specified operational condition. Scheduled maintenance covers periodic inspections, condition monitoring, critical-item replacements (prior to failure), periodic calibration, and the like. In addition, servicing requirements (e.g. fueling and lubrication) may be included under scheduled maintenance.

  
• Preventive Maintenance Involves


  • Periodic inspection of equipment/machinery to uncover condition that lead to production breakdown and harmful depreciation. Upkeeps of plant machinery to correct such conditions while they are still in a minor stage
  • Regular cleaning, greasing and oiling of moving parts
  • Replacement of worn out parts before they fail to operate
  • Periodic overhauling of the entire machine
  • Machines or equipment's which are liable to sudden failures should be installed in duplicate e.g. motors, pumps, transformers and compressors etc.

  
• Features of a well-conceived preventive maintenance programme

  • Proper identification of all items to be included in the maintenance programme
  • Adequate records covering, volume of work, associated costs etc.
  • Inspection with a definite schedule with standing order on specific assignments
  • Use of checklists by inspectors
  • An inspection frequency schedule
  • A crew of well qualified inspectors with competency of simple repairs, as and when small trouble is noticed
  • Administrative procedures which provide necessary fulfilment as well as follow up on programme

  
• Seven Elements of Preventive Maintenance (CASTIIA)

  • Inspection
  • Servicing
  • Calibration
  • Testing
  • Identification
  • Adjustment
  • Analysis

  
• Inspectors


  With competency of simple repairs, as and when small trouble is noticed
• Administrative procedures


  Provide necessary fulfilment as well as follow up on programme
• Seven Elements of Preventive Maintenance (CASTIIA)

  • Inspection
  • Servicing
  • Calibration
  • Testing
  • Alignment
  • Adjustment
  • Installation

  
• Inspection


  Periodically inspecting materials/items to determine their serviceability by comparing their physical, electrical, mechanical, etc., characteristics (as applicable) to expected standards
• Servicing


  Cleaning, lubricating, charging, preservation, etc., of items/materials periodically to prevent the occurrence of incipient failures

  
• Calibration


  Periodically determining the value of characteristics of an item by comparison to a standard; it consists of the comparison of two instruments, one of which is certified standard with known accuracy, to detect and adjust any discrepancy in the accuracy of the material/parameter being compared to the established standard value
• Testing


  Periodically testing or checking out to determine serviceability and detect Electrical & mechanical-related degradation
• Alignment


  Making changes to an item's specified variable elements for the purpose of achieving optimum performance
• Adjustment


  Periodically adjusting specified variable elements of material for the purpose of achieving the optimum system performance
• Installation


  Periodic replacement of limited-life items or the items experiencing time cycle or wear degradation, to maintain the specified system tolerance
• Improper motor alignment


  • Beat marks from sledgehammer, missing push bolts, too many shims under feet
  • Correct motor alignment setup
• Hydraulic unit inspection


  • Leaks take 20-30 min to inspect on left unit
  • Leaks can be inspected in 10 sec on right unit by looking for oil in pan
• Characteristics of a plant in need of a good Preventive Maintenance program:

  
• Six steps for establishing a highly effective PM program in a short period

  1. Identify and choose the areas

  2. Identify the PM needs

  3. Establish assignment frequency

  4. Prepare the PM assignments

  5. Schedule the PM assignments on annual basis

  6. Expand the PM program as necessary
• Maintenance Levels


  • Level I Preventive Maintenance
  • Level II Preventive Maintenance
  • Level III Preventive Maintenance
  • Level IV Preventive Maintenance
  • Level V Preventive Maintenance

  
• Level I Preventive Maintenance


  Includes simple maintenance activities that are essential to the operations, and are carried out on easily and safely accessible elements thanks to machine-integrated support equipment. This type of operations may be carried out by the production operator and scheduled.

  
• Level II Preventive Maintenance


  Includes operations which require complex procedures. A qualified technician with detailed procedures may carry out this type of maintenance operations.

  
• Level III Preventive Maintenance


  Dedicated to operations whose procedures imply particular techniques or technologies. A qualified technician or team with any general or special maintenance instructions may carry out this type of maintenance operations.