Designation used for the type of 5-axis spindles in the 5-axis-CNC-machining.
The units nowadays labelled as "Cardan head" consist of a milling spindle, which is fixed with at least 2 torques on unit carriers. This also complies with the principle called robot head which derived from joint arm robots. Important details is the single-sided fixation of the milling spindle.
This name were technically correct for the usual spindles called forkshaped head, as a cardan joint (from which the name derives), is suspended double-sidedly.
The name cardan head has been changed semantically over the course of time for 5-axis-spindles with single-sided suspension. Especially with the introduction of the DRIVE 5C spindle ("C" stands for "Cardanic") through the manufacturer HOMAG the name finally pushes through for the single-sidedly suspended spindles.
From mechanical engineering´s point of view, cardan heads have a lower rigidity than forkshaped heads, but have higher dynamics and a lower demand on space. Therefore, some manufacturers use both principles in different model series.
Many manufacturers, therefore, distinguish between cardan head for spindles suspended from one side and fork-shaped head for spindles suspended from two sides.
As special form of the cardan head there is the prism head, where single torques are not arranged rectangularly but composed in slanted angles towards each other. This is nowadays the most frequently-used form in woodworking of 5-axis spindles. But the name is mainly used by the manufacturer SCM as "Prisma" is a brand name for their 5-axis-heads.