416 Modern Welding When cutting steel plates thicker than 1″ (25.4mm), some drag is desirable to ensure the proper amount of oxygen is consumed. This results in an even cut. Drag is a measurement, made in the direction of travel, between the entry and exit points of the cutting jet. See Figure 14-14. If the slag stream lags excessively behind the torch tip travel, the following are possible causes: The fl ame adjustment may be incorrect. The cutting oxygen pressure adjustment may be too low. The tip travel is too fast and the metal is not being preheated enough. 14.5.1 Cutting Attachments Most manufacturers of oxyfuel gas welding and cutting torches market a cutting attachment. The attachment is connected to the welding torch body to change the torch from a welding torch to a cutting torch. Review Heading 14.4 for more information on cutting torch attachments. The cost of such an attach- ment and the welding torch is usually less than the cost of a separate welding torch and a cutting torch. For portable kits, this attachment saves space. To connect a cutting attachment, remove the welding tip tube and screw on the cutting attachment. Kerf 1/16″ to 1/8″ (1.6 to 3.2mm) No drag under 1 inch thickness Direction of travel Uncut Figure 14-13. The cutting torch position used for cutting with the oxyfuel gas cutting torch. The cutting head and tip are tilted away from the direction of cutting at a 5°–20° angle from vertical. Cutting oxygen orifice Preheat orifices A Cutting axis and direction of travel Kerf Slag B Steel plate Direction of torch travel C Drag Figure 14-14. An oxyacetylene cut in progress. A—Note the slag at the bottom of the kerf. B—Cut in progress with some slag at the bottom of the plates. C—Cutting oxygen slows down as it travels through the metal. Drag results from the oxygen slowing down and the forward motion of the torch.
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