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Rotary Lip Seals
Published in Heinz K. Müller, Bernard S. Nau, Fluid Sealing Technology, 2019
Heinz K. Müller, Bernard S. Nau
Eccentricity: The effect of angular shaft-to-seal offset, a slanted contact line, has already been discussed. Elastomeric lip seals normally tolerate a static radial offset up to 0.2–0.3 mm without loss of sealing. By contrast, dynamic runout of the shaft (dynamic eccentricity) at higher speeds can cause leakage. Dynamic run-out can arise from out-of-roundness of the shaft or radial vibrations of the shaft. If, due to inertia or viscoelasticity, the seal lip cannot follow the radial motion of the shaft, an interfacial gap is created allowing oil to escape. Maximum allowable dynamic run-out depends on seal design and the elastomer used. Depending on speed, the maximum permitted run-out is typically 0.1–0.3 mm. Some specially designed lip seals for automotive crankshafts have a more flexible membrane, allowing more dynamic run-out than normal. However, leakage due to dynamic run-out or other reasons is not inevitable; additional protection is available in the form of various hydrodynamic sealing aids.
Signal Processing in Rotating Machinery
Published in Rajiv Tiwari, Rotor Systems: Analysis and Identification, 2017
The mechanical run-out present may be due to an eccentric shaft, bent shaft, or to an uneven rotor surface where vibration is being monitored. The electrical run-out is present due to variation in permeability of the shaft material at location of measurement. This may be due to the residual magnetic field, or residual stresses, and due to material inhomogeneity where the electrical field of the transducer is applied during measurement. Commonly used noncontact proximity transducers rely for their work on a variation in transducer reactance and the above mentioned reasons lead to an effect on the transducer reactance. These run-outs need to be corrected mechanically (machining, polishing, and removal of bend) or electrically (degaussing and electroplating). The mechanical run-out can be measured by a dial gauge while rotating the shaft slowly. With a transducer during slow roll (speed of the rotor is such that no vibration is expected in measurement) both mechanical and electrical run-out can be measured. Vectorial subtraction of the above two measurements will give the electrical run-out. From the actual measured signal the total run-outs can be subtracted again vectorially as depicted in Figure 16.54.
Tolerancing
Published in Ken Morling, Stéphane Danjou, Geometric and Engineering Drawing, 2022
This kind of specification refers to circular run-out and total run-out tolerances in axial or radial direction. Although these geometrical tolerances represent a special type of orientation and location tolerances, according to ISO 1101 they are considered to be a separate category due to the required measuring method which differs from the other geometrical tolerances.
Effect of ultrasonic-assisted turning on geometrical tolerances in Al 2024-T6
Published in Materials and Manufacturing Processes, 2021
Masuod Bayat, Saied Amini, Mohsen Hadidi
Runout indicates the workpiece tolerance conditions when a workpiece is rotated 360 degrees around the datum axis. This is basically the control of a circular property and how much it changes with the axis of rotation. Runout is achieved by rotating the workpiece around its axis. Runout can be measured using a height gauge that is put on a fixed reference surface. All the points of the workpiece are measured relative to a fixed reference point. The workpiece is then rotated around its axis, and its change is measured using a height gauge perpendicular to the surface of the workpiece. Measuring the total runout is the same as measuring the runout, except that the dial indicator must be moving on the workpiece as the workpiece rotates. Figure 8 and Fig. 9 show the effect of the spindle speed on the runout and total runout. According to Fig. 8 and Fig. 9, with increasing spindle speed, the amounts of the runout and the total runout of the workpiece are reduced, and this reduction is more in the UAT state than in the CT state. As seen in the diagram, increasing the spindle speed has a positive effect on the runout and total runout. In the presented diagrams, it can be seen that the only parameter that has a positive effect on the runout and total runout tolerances is the spindle speed. In fact, increasing this parameter increases the heat transfer, softens the material in the cutting area, and improves the tolerances. According to previous research, [29,30] vibration-assisted machining has reduced the heat generated during machining. Therefore, this heat reduction reduces the deformation in the workpiece and reduces the distortion and deformation of the workpiece. Figure 10 also demonstrates the effectiveness of different turning parameters on the runout tolerance. As the spindle speed increases, the runout tolerance reduces in the ultrasonic turning method. In the vibrational mode, the reduction in the runout tolerance is greater and improves the workpiece quality.
Analysis of cutting forces at different spindle speeds with straight and helical-flute tools for conventional-speed milling incorporating the effect of tool runout
Published in Mechanics Based Design of Structures and Machines, 2022
There are two types of tool runout, radial and axial. The axial runout, whose influence on the cutting forces is disregarded, is very small compared to the axial depth. However, the radial runout has the same order as feed per tooth (Li and Li 2004). Therefore, the analysis is focused on radial runout, which is described as the offset of tool from the axis of rotation.