Preventive Maintenance

Preventive Maintenance:

Preventive Maintenance BY ANIRBAN HALDER

What is Preventive Maintenance? :

What is Preventive Maintenance? Preventive maintenance is planned maintenance of plant and equipment that is designed to improve equipment life and avoid any unplanned maintenance activity. Preventive Maintenance includes painting, lubrication, cleaning, adjusting, and minor component replacement to extend the life of equipment and facilities. Its purpose is to minimize breakdowns and excessive depreciation. It is the maimtanance before any breakdown. In its simplest form, preventive maintenance can be compared to the service schedule for an automobile.

Reasons for Preventive Maintenance :

Reasons for Preventive Maintenance Increased Automation Business loss due to production delays Reduction of insurance inventories Production of a higher quality product Just-in-time manufacturing Reduction in equipment redundancies Cell dependencies Minimize energy consumption Need for a more organized, planned environment

Elements of a good preventive maintenance program :

Elements of a good preventive maintenance program Identification of equipment or systems that may malfunction Typical equipment to be inspected including switchgear, circuit breakers, transformers , switches, etc. Establishment of schedules and procedures for routine inspections Periodic testing of plant equipment for structural soundness Prompt repair or replacement of defective equipment found during inspection and testing Inventory of spare parts for equipment that needs frequent repairs Use of an organized record-keeping system to schedule tests and document inspections Commitment to ensure that records are complete and detailed, and that they record test results and follow-up actions Preventive maintenance inspection records should be kept with other visual inspection records

Objectives of Preventive Maintenance:

Objectives of Preventive Maintenance ( i ) To minimize the possibility of unanticipated production interruption or major breakdown by locating or uncovering any condition which may lead to it. (ii) To make machine tools always available and ready for use. (iii) To maintain the optimum productive efficiency of the machine tools. (iv) To maintain the operational accuracy of the machine tools. (v) To reduce the work content of maintenance jobs. (vi) To achieve maximum production at minimum repair cost. (vii) To ensure safety of life and limb of the machine tool operators. (viii) To maintain value of machine tools (by periodic inspections, repairs, overhauls etc.)

Advantages of Preventative Maintenance:

Advantages of Preventative Maintenance Safety . Machinery that is not well-maintained can become a safety hazard. Preventive maintenance increases the margin of safety by keeping equipment in top running condition. Lower cost . A modern and cost-effective approach to preventive maintenance shows that there is no maintenance cost optimum. However, maintenance costs will decrease as the costs for production losses decreases. Obviously, no preventive maintenance action is performed unless it is less costly that the resulting failure. Reduction in failures and breakdowns . Preventive maintenance aims at reducing or eliminating unplanned downtime, thereby increasing machine efficiency. Downtime is also reduced when the preventive maintenance process gives maintenance personnel sufficient warning so repairs can be scheduled during normal outages. Extension of equipment life . Obviously, equipment that is cared for will last longer than equipment that is abused and neglected. Improved trade-in/resale value of equipment . If the equipment is to be sold or traded in, a preventive maintenance program will help keep the machine in the best possible condition, thereby maximizing its used value. Increased equipment reliability . By performing preventive maintenance on equipment, a firm begins to build reliability into the equipment by removing routine and avoidable breakdowns.

Cont…:

Cont… Increased plant productivity . Productivity is enhanced by the decrease in unexpected machine breakdown. Also, forecast shutdown time can allow the firm to utilize alternate routings and scheduling alternatives that will minimize the negative effect of downtime. Fewer surprises . Preventive maintenance enables users to avoid the unexpected. Preventive maintenance does not guarantee elimination of all unexpected downtime, but empirically it has proven to eliminate most of it caused by mechanical failure. Reduced cycle time . If process equipment is incapable of running the product, then the time it takes to move the product through the factory will suffer. There is a strong correlation between preventive maintenance and cycle-time reductions as well as near-perfect on-time delivery rates. Increased service level for the customer and reduction in the number of defective parts. These have a positive direct effect on stock-outs, backlog, and delivery time to the customer. Reduced overall maintenance . By not allowing machinery to fall into a state of disrepair, overall maintenance requirements are greatly decreased.

Disadvantages of Preventive Maintenance :

Disadvantages of Preventive Maintenance ( i ) Breakdowns generally occur at inopportunate times. This leads to poor, hurried maintenance and excessive delays in production. (ii) Reduction of output. (iii) Faster plant deterioration. (iv)Increased chances of accidents and less safety to both workers and machines. (v) More spoilt material. (vi)Direct loss of profit. ( vii)Unplanned downtime can't be excluded. (viii) Labour intensive. (ix) Unneeded maintenance of some component.