Machine data gathering

M, weight-average molecular weight MDG machine data gathering... 

The process of vibration analysis requires gathering complex machine data and deciphering it. As opposed to the simple theoretical vibration curves shown in Figures 43.1 and 43.2, the profile for a piece of equipment is extremely complex. This is tme because there are usually many sources of vibration. Each source generates its own curve, but these are essentially added together and displayed as a composite profile. These profiles can be displayed in two formats time-domain and frequency-domain. 

Vibration data are obtained by the following procedure (1) mounting a transducer onto the machinery at various locations, typically machine housing and bearing caps, and (2) using a portable data-gathering device, referred to as a vibration monitor or analyzer, to connect to the transducer to obtain vibration readings. 

As illustrated in Figure 43.11, the peak-to-peak amplitude (2A, where A is the zero-to-peak) reflects the total amplitude generated by a machine, a group of components, or one of its components. This depends on whether the data gathered is broadband, narrowband, or component. The unit of measurement is useful when the analyst needs to know the total displacement or maximum energy produced by the machine s vibration profile. 

An operator interface is used to record data gathered by the PLC.1 The operator interface is usually another computer (sometime called the human-machine interface or HMI). The HMI uses process displays with real-time sensor readings so that the operator can quickly assess the status of the system (see Figure 6.17). The operator uses the control panel to adjust alarm settings and to turn on and off process equipment. Once running, however, the PLC controls and runs the system automatically, without further input from the operator. Common HMI status indicators are listed below ... 

Technology involves the use of systems, tools, and machines that gather, process, and communicate data and information within and between firms. As such, they enable real-time monitoring and visibility of the supply chain. Finally, people are the human entities that implement procedures and use the technology in order to build continuity. 

To achieve effective monitoring and diagnostics of turbomachinery, it is necessary to gather and analyze both the mechanical and aerothermal operating data from the machines. The instrumentation and diagnostics must also be custom tailored to suit the individual machines in the system, and also to meet the requirements of the end users. The reasons for this are that there can be significant differences in machines of the same type or manufacturer because of differences in installation and operation. 

There are several options regarding the types of vibration data that can be gathered for machine trains and systems and the formats in which it can be collected. However, selection of type and format depends on the specific application. 

Most predictive-maintenance programs rely almost exclusively on frequency-domain vibration data. The microprocessor-based analyzers gather time-domain data and automatically convert it using Fast Fourier Transform (FFT) to frequency-domain data. A frequency-domain signature shows the machine s individual frequency components, or peaks. 

Determine the frequency of data collection and the size of the subgroup. A subgroup is defined as a few measurements gathered from the same logical grouping (i.e., data from the same machine on same shift in short period of time). 

Engineering Data on the Classifiers.—Complete data on the performance of these machines is very difficult to obtain. The data given below is the most complete for the installations given that it has been possible to gather. Much of the published and private data which can be obtained is lacking in some important and essential feature and it is not deemed worth while submitting. 

The methods of gathering and analyzing lubricant properties and conditions vary widely. Analytical instruments and procedures are often employed in a laboratory to determine important properties of routinely sampled lubricants. Similar instruments can be used remotely in the plant. This practice is often referred to as onsite analysis. In certain cases the instruments or sensors can be used in real time, dedicated to a specific machine and fluid. The management and reporting of lubricant analysis data is typically conducted with the aid of a computer and software developed for this purpose. 

The more detailed the data, the more detailed the possible analysis you can always consolidate data after they is gathered, but you can t break the data down if they are consolidated before they are gathered. Computerization permits detailed recording and thus analysis of downtime, machine breakdown, setup time, and so on. With bar coding of parts and computer terminals at workstations, it is feasible to record times for each individual part. For example, for product Y, operator 24 completed operation 7 on part 1 at 10 05, part 2 at 10.08, and so on. More commonly, however, you would just record that for product Y, operator 24 started operation 7 at 10 00 and completed the 25 units at 11 50. Least useful would be recording, for product Y, that all operations on 25 units were completed on Tuesday. Companies tend to develop elaborate codes for types of downtime, quality problems, and so on. Be careful about downtime reporting it is easy to abuse. 

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