Oxygen plasma arc cutting characteristics and cat surface quality factors are discussed in this paper. It has been carried out to cut the SS400 workpieces with various plate thicknesses. Such measurements as top and bottom kerf widths, bevelangle, straightness, dross attached level and cut surface roughness are used to evaluate the cut surface quality. A new classification method of the dross attached level, by which the dross attached level is classified into three kinds of states, is putforward. Influence of cutting conditions on cut shape and cut surface state is investigated in detail. With the increase of cutting speed and the decrease of arc current, kerf width decreases, bevel angle increases, white straightness varies within avariation range of about 0.2 mm for the thicknesses of 3.2 to 8.0 mm. And compared with top kerf width, bottom kerf width more rapidly decreases. Moreover, with the increase of cutting speed, the cut surface roughness exhibits a slight drop regardless ofarc current, and under the present conditions the smoother cuts of R{sub}z less than about 40μm are obtained.It is proved that the dross attached state bears relation to not only cutting heat input but also arc current and plate thickness. There are two dross attached areas, respectively, occurring under low and high cutting heat inputs. The heat input rangeobtaining the dross-free cut varies with plate thickness. The dross-free area gets wider when cutting current increases. Furthermore, it has been made clear that kerf width and bevel angle are approximately in linear proportion to the logarithm ofcutting heat input for a given thickness, respectively. A vertical cut can be available under high cutting heat input.
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