The steep-angle taper shank has no self-locking and thus, provides the most important requirement for an automatic tool change. Furthermore, this is allowed because of the bolt located on its top.
The steep-angle taper according to standard ISO30 has a relatively compact design and therefore, can often be found in smaller and lighter CNC-machining centres. Because of the relatively small contact area and the resulting lower clamping forces, it is only of limited suitability for heavy milling; this is where ISO40 is mostly used. However, for processing at high speeds it is more suitable, due to its lower mass.
Since the mid-2000s, the steep-angle taper is hardly used for new machines, because it was replaced by the hollow shaft taper (HSK-F63).