Coordinate Measuring Machine (CMM)

Coordinate Measuring Machine (CMM) is the logical capability of dimensionally inspecting a manufactured part by probing discrete points on its surface and comparing them to the nominal CAD geometry and GD&T tolerances. CMMs come in bridge, gantry, cantilever, and articulated-arm form factors, with contact (touch-trigger) or non-contact (laser, optical, CT) sensing.

What it covers

• Part probing — touch-trigger, scanning, or optical capture of measured points.
• Alignment — datum reference frame construction from the GD&T scheme.
• Feature evaluation — size, form, orientation, and location with tolerance verification.
• First-article inspection (FAI) and statistical process control sampling.
• Inspection programming — increasingly model-based via QIF and DMIS.

Relationships (see sidebar)

• Supports Quality Management, Prototyping and Validation, and Manufacturing Execution.
• Conforms to the QIF (ISO 23952) standard for model-based inspection data exchange.
• Closely tied to the GD&T capability — the CMM verifies what GD&T defines.