Probe Head

A probe head is a critical component of a Coordinate Measuring Machine (CMM) that serves as the interface between the machine's moving arm and the actual tactile or non-contact probe. It is responsible for holding the probe securely and, in many modern systems, providing motorized or manual rotation in multiple axes (typically A and B axes) to orient the probe at various angles. This capability allows the CMM to measure complex geometries, internal features, and undercuts without requiring manual repositioning of the workpiece. The probe head transmits measurement signals from the probe back to the CMM's control system and often includes mechanisms for automatic probe changing, probe qualification, and collision detection.

The probe head operates by providing a rigid yet precisely controllable mounting platform for the probe. In manual heads, the orientation is locked or adjusted by hand. In motorized (indexing or continuous) heads, servo motors rotate the probe around one or two orthogonal axes to predefined angular positions or continuously during scanning. The head maintains positional accuracy through high-precision bearings and angular encoders. It connects electronically to the CMM controller, relaying trigger signals from the probe's contact event and receiving commands for movement. Some advanced heads also incorporate strain gauges or other sensors for dynamic error compensation and crash protection.