Data Analysis Tip 1 – Consider the Machine First and Then the Graphs

www.dliengineering.com
posted 3-7-05

A common approach to looking at vibration spectra is to display the graphs and then ask “What is wrong with this machine?” Another common approach to analyzing vibration spectra is to display the graphs and then ask “What is this peak?” and “what is that peak” A better approach to analyzing data is to first ask “What faults can this machine have?”, “Which of these are most common for this machine?” and finally, “How do these faults present themselves?” In fact, these questions should really be asked before the machine is tested. It may turn out that vibration analysis isn’t even the appropriate technology to use to find the most common faults in this machine.

A good exercise is to draw a simple schematic of the machine including test points and internal components, then write down a list of the most common faults the machine may experience. Between the diagram and a vibration text book or reference chart, you can now describe what peaks and patterns in each test point will coincide with each fault. Finally, go down the list of faults and patterns and check the data to see if it contains any of these patterns or not.