The effect of magnetic shaking on nonoriented silicon steel rings
The effect of magnetic shaking on the incremental permeability of nonoriented silicon steel rings was studied. 50H470 silicon steel is a very popular and cheap material, but does not have a high incremental permeability. However, we achieved a value of 27 000 for the target field of 10 Hz, 0.05 A/m, which is comparable to commercial PC permalloy. We also measured the target field, which ranged from 0.05-5 A/m, 1 Hz-1 kHz. Magnetic shaking was effective at 60 Hz is effective at shaking field amplitudes 40-60 A/m, corresponding to a flux density of 0.2-0.6 B/sub s/. We also made ring samples from 50H470 steel plates produced by a nibbling machine and evaluated the effect of stress on their magnetic properties.
Effect of a Superposed Alternating Field on Apparent Magnetic Permeability and Hysteresis Loss
It is often assumed that when an alternating magnetizing force is superposed on a constant magnetizing force, the permeability of the magnetic material is increased and the hysteresis loss decreased owing to the shaking-up action of the alternating field on the magnetic particles. It is shown that these effects are only apparent and that the true permeability and hysteresis remain approximately the same as under constant field conditions. What are actually measured are the midpoints of displaced minor hysteresis loops. From the known laws of variation of these minor loops the apparent magnetization curves and hysteresis loops under a superposed alternating field can be calculated. The method of doing this is illustrated. Under these assumptions a superposed alternating field actually increases the hysteresis loss instead of suppressing it as has often been assumed, the resulting hysteresis including losses due to displaced minor loops besides those due to an increased major loop. These conclusions are supported by magnetization curves obtained with 1 percent Si steel punchings which are shown to agree with the calculated curves. Some consideration is given to the case when the fields are at right angles but at present it is not susceptible to quantitative calculations.
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.