Understanding the Basic Concept of Manufacturing Equipment Preventive Maintenance

Preventive maintenance is also known as Time-based or Calendar based maintenance. Maintenance activities are performed on a calendar or fix operating schedule in order to extend the life of the equipment and prevent failures. In preventive maintenance, maintenance is performed without regard to equipment condition. It assumes that the condition of the machine and the need for maintenance is correlated with time which means that the item can be expected to operate reliably for an amount of time and is expected to wear out. A failure rate and history records are used to established the best frequency. Therefore, a preventive maintenance is simply performing maintenance on a fixed interval which may in the form of time, number of strokes or frequency.

Stress can cause an asset to deteriorate by lowering its resistance, exposure to stress includes output, distance traveled, operating cyscles, calendar time and running time. When the part or component wears out directly with respect to its operating age, these parts will survive this defined age (example, 98% of impelers were replaced after the end of 2 years). The part or component will have a normal rate of wear, TPM term will be normal fatigue. Fatigue happens when stress exceeds the strength of the material of the spare part or component. Application of Preventive Maintenance task will only be worth doing and feasible to parts that will have a normal wear or deterioration.

Preventive maintenance will include regular checking, cleaning and inspecting, scheduled parts replacement and controlling, regular routine lubrication, regular calibration, periodic preventive maintenance schedule and monitoring activities. Replacement of parts or overhauls is either based on time-dominated frequency number of strokes or running hours. There is a high probability of failure at the end of the period and failure will survive up to this point, then Preventive Maintenance is worth doing.

But, preventive maintenance is limited when founded on the belief that a given history of failures of a given components failing after a certain number of hours used or other measurements. But most parts based on the averages. Preventive Maintenance carry out the maintenance work at regular intervals, problems with this practice is that since most tasks are based on the average maintenance may carry out work that is not required and probability of replacing parts which are still in working conditions. Since this is a Time-based Maintenance, studies have shown that most of equipment failures are not related to the number of hours.