Why and How Machines fail?
Module: Maintenance Strategy
Name: Vashish Boolauky
Id no: 102019
WHY AND HOW MACHINES FAIL?
Failure of a machine tool may occur due to failure(s) in any of the elements of the subsystems. The failure may be attributed to specific failure causes. A failure cause is defined as a reason that makes the machine unable to perform its intended function. This may be attributed to failure events contributed by its subsystems, assemblies, or components.
Machines fail for a variety of reasons. Likewise, not all failures are the same. The term "machinery failure" or "malfunction" usually implies that the machine has stopped functioning the way in which it was intended or designed. This is referred to as “loss of usefulness” of the machine or component. For instance, if a pump is installed to pump 100 gallons of oil per minute but over time can no longer keep up and now only pumps 75 gallons per minute, this is a loss of usefulness of the asset.
This loss of usefulness is broken down into three main categories: obsolescence, surface degradation and accidents. Of these three, surface degradation of machine parts results in the machine’s loss of usefulness in the vast majority of cases. Surface degradation is comprised mainly of corrosion and mechanical wear. Corrosion of machine parts is quite common, especially for those with water-contamination issues. Water not only rusts iron surfaces, but it can also increase the oil’s oxidation rate, leading to an acidic environment within the component.
Acids can also be formed as byproducts of reactions between certain additives in the oil and water. Product contamination through seals can create caustic environments and corrosive wear as well. Something as simple as having an aggressive extreme-pressure additive in contact with a yellow metal (copper, bronze, brass, etc.) can produce corrosive damage. Mechanical wear occurs when machine surfaces mechanically wearing against...