alignment and balancing

Presented by Troy Feese

There are several commercially available software packages, such as SMS Star and ME'Scope, that can be used to perform operating deflection shape (ODS) measurements.

This article provides a case history of a forced draft (FD) fan that experienced high vibration due to unbalance and an impeller resonance near the operating speed. The common balancing method of influence coefficients was unsuccessful due to varying phase data. However, vibration was reduced to an acceptable level using the four-run method without phase data.

As anyone who has practiced vibration analysis knows, vibration signatures obtained on routes are often far from the wall chart examples. The reason for this is that the vibration signatures collected and analyzed represent the response of a system due to a variety of different forces that act simultaneously to produce one signature. Unfortunately, vibration analysts are actually interested in determining the individual forces that cause the response. Once the forces are accurately identified, only then can they be reduced or eliminated.

By Chad Wilcox

You can use the Rim & Face Method to perform a calculated precision alignment process. You may use a variety of shaft alignment fixtures. We recommend that you use a commercial package designed to accommodate a variety of shaft diameters. The fixtures should include an assortment of rods to span various coupling lengths. These packages expedite the precision alignment process. Also, sag values can be pre-determined for the standard rod
assortment.

By VibrAlign, Inc.

This paper addresses a vexing problem that has plagued machine reliability professionals for decades. Despite the best efforts to precisely align rotating machinery shafts, dynamic movement (mostly manifested by the thermal growth of the machine casings) has resulted in machines operating at less than optimum alignment conditions.

By Alan Luedeking
The shaft alignment of large vertical condensate pumps in power plants is a challenging application. The pump shaft and impeller are rigidly coupled to the vertical flange-mounted motor.

By S. Ganeriwala, S. Patel, H. A. Hartung

1. Abstract

Misalignment is probably the most common cause of machinery malfunction. Considering the importance of alignment, the vibration spectra of alignment is not well documented. Various authors have reported different spectra. The goal of this research was to determine the unique vibration signature for misalignment at varying operating and design conditions such as speed, type and level of misalignment, coupling types and machinery dynamic stiffness. The SpectraQuest Machinery Fault Simulator™ was used in the study to create the varying mechanical conditions.

By Gary K. Grim, Bruce J. Mitchell

Why Balance? All rotating components experience significant quality and performance improvements if balanced. Balancing is the process of minimizing vibration, noise and bearing wear of rotating bodies. It is accomplished by reducing the centrifugal forces by aligning the principal inertia axis with the geometric axis of rotation through the adding or removing of material. In order to understand the basics of balancing it is necessary to define the following fundamental terms.