Tham khảo tài liệu 'navfac p-433 welding materials handbook_11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ToSimpogPDFMergeand Split Unregistered Version An angled torch cuts faster on thinner-gauge material. The intersection of the kerf and the surface presents a knife edge which is easily ignited. Once the plate is burning the cut is readily carried through to the other side of the work. This avoids problems of non-drop cuts incomplete cutting on the opposite side of the thicker plate gouging cuts in the center of the kerf and similar problems. Travel Speed Each job has a best cutting speed. A high quality cut will be obtained on plate up to about 2 in. thick when there is a steady purring sound from the torch and the spark stream under the plate has a 15 degree lead angle the angle made by the sparks coming from the bottom of the cut in the same direction the torch is traveling. If the sparks go straight down or even backwards travel speed is too high. Nature of the Workpiece Variations in cut quality are the result of different - http workpiece surface conditions or plate compositions. For example rusty or oily plates require more preheat or slower travel speeds than clean plates. Most variations from the ideal condition of a clean flat low-carbon steel plate tend to slow down cutting action. For a very rusty plate set as big a preheat flame as possible on the torch and run it back and forth over the line to be cut. Extra preheat passes do two things. First they span off much of the scale that interferes with the cutting action and they put extra preheat into the plate to allow improved cut quality and speed. Cut a little bit slower when working with high-strength low-alloy plates ASTM A-242 steel or full alloy plates AsTM A-5 14 . Also because these steels are more sensitive to notching than ordinary carbon steels use low oxygen pressure. Clad carbon alloy carbon stainless or low-carbon-high-carbon plates require a lower oxygen pressure and perhaps a lower travel speed than straight low-carbon steel. Be sure the low-carbon steel side is 4-17 Simpo
