Abstract: The invention concerns EI-type core laminations, especially for transformers. The E-piece has a center leg of width f, two outer legs of width b, a yoke of width c.sub.1 and two windows of width h and length e. The I-piece has the width c.sub.2. The laminations have the following ratios:e is greater than 3 f/2 and less than 3.5 f/2;c.sub.1 and b are both at least 1.1 f/2;c.sub.1 -c.sub.2 is at least 0.1 f/2;c.sub.1 +c.sub.2 is at least 2.1 f/2 and at most 2.5 f/2.A preferred embodiment of the invention has the ratios:e=3.25 f/2; c.sub.1 =b=1.25 f/2; c.sub.2 =h=f/2.

Abstract: Core laminations of the UI or EI type for iron cores, particularly for transformers, having two or three legs of equal length e and equal width f, spaced mutually apart by the same distance h, wherein the width c.sub.1 of the jointlessly connecting yoke is greater than the width c.sub.2 of the parted yoke, using the following dimensions: 1.1f.ltoreq.c.sub.1 .ltoreq.2.1f and 1.0f.ltoreq.c.sub.2 .ltoreq.1.5f and 0.1f.ltoreq.c.sub.1 -c.sub.2 .ltoreq.0.6f. Preferred dimensions for a waste-free UI shape and a suitable EI shape are: c.sub.1 =1.4f; c.sub.2 =h=1.2f; e=3.2f. Preferred dimensions for a waste-free EI shape are: c.sub.1 =1.5f; c.sub.2 =h=1.2f; e=2.7f.