Oleg Delendyk Jan 8, 2012:

two-dimensional (2-D) and three-dimensional (3-D) Closed impeller construction with backward-leaning vanes offers a wide operating range. Two versions are available: two-dimensional (2-D) and three-dimensional (3-D) configurations. Fig. 1 shows a 3-D impeller being contour-milled from one single piece of metal. This type of contour milling is ranked among the favored fabrication processes and is not to be confused with techniques whereby individual blades are being welded to an impeller hub.1
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