Like bar drawing, tube drawing is accomplished in most cases with the use of draw bench. Fixed mandrel (Figure 21.9a) is most commonly used to control the tube’s internal diameter; Figure 21.9b uses floating mandrel which adjust itself to the correct position because of its stepped contour; cylindrical mandrel (Figure 21.9c) is usually used for small-sized tubing, and Figure 21.9d which does not use any mandrel or rod and has no control over inside diameter. By repeated cold drawing and annealing when necessary it is possible to reduce a 2 in. diameter to size of hypodermic needle, which has an outside diameter of about 0.008 in.
Figure 21.9 Tube Drawing Processes
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