The “P” and “M” here do not stand for preventive or productive maintenance. “P” is for phenomenon — the thing that occurs, even where it can be controlled — and also for physical, meaning the physics that is the cause of that phenomenon. “M” means mechanism, and also the inputs to production, the 4M: man, machine, method and material.
Why this matters
Excellent plant performance is a decisive factor in building an organisation’s ability to compete in present conditions — producing goods of quality, delivering on time, and staying flexible to what the customer wants, all of it under an awareness of reducing and controlling production cost.
Yet excellent plant performance cannot come about while the machines and equipment in the process are not a hundred percent reliable — which follows from maintainability that is not a hundred percent either.
The important cause is breakdown maintenance that is not done properly — that is, only solving the problem in front of you, without finding the true cause or the root of it. This may be for want of awareness, or for want of a tool to help find that root.
What the analysis is for
Which chronic failure gives rise to defects or to breakdown, according to how the machine works
Detecting the conditions under which an abnormality will arise
Which factor gives rise to each phenomenon, in terms of the 4M
Where the name comes from
Step 1 of P-M analysis is to study the basic principles on which the machine was built, its mechanism and its structure. That study puts us in a position to analyse the phenomena arising on the machine, looked at through what is possible according to physics — which is step 2. This step is the decisive beginning: whether or not we shall be able to find the true cause of the breakdown.
In step 3 we set out every condition under which that phenomenon could arise. We then observe which of the production inputs, the 4M, create those conditions, and draw the conclusions and analyse them through steps 4, 5, 6 and 7 in turn. In step 8 we make the improvements to correct every factor found to be abnormal.
P and M
P — phenomenon and physical · the variation visible over the period in which the failure arises · analysis to understand how the machine works according to physics
M — mechanism · understanding the mechanism, what is normal in it and what is abnormal · studying the working principle of each mechanism
4M — machine, man, material, method · finding the abnormality arising from the machine, the person and the way the work is done · analysing for cause and effect