Manufacturing & engineering
Clearance
Definition
Clearance is the positive space between components, often measured in CAD as their minimum nominal separation. Required clearance must account for function and manufacturing variation; the absence of geometric interference does not by itself provide enough clearance.
Also known as: assembly clearance, minimum clearance
Updated
Static and dynamic clearance#
SOLIDWORKS Clearance Verification checks the minimum distance between selected assembly components and reports separations below a specified acceptable value. This is a static check at the current component positions.
Dynamic Clearance reports the changing minimum distance while a component moves or rotates. A mechanism can satisfy the required clearance at its endpoints and breach it somewhere between them, so the intended travel must be part of the check.
Clearance is not the same as tolerance#
CAD geometry normally represents nominal sizes. A nominal positive gap can shrink or disappear when the manufactured parts vary within their allowed dimensions. ASME Y14.5 defines a system for communicating dimensional and geometric requirements, but the designer still has to choose tolerances that preserve the functional gap.
Clearance can also be required for coating, thermal growth, lubrication, tool access, electrical isolation, cable movement, or safe human access. The minimum acceptable value comes from the product's function and process, not from the CAD tool.
Limits of a clearance result#
A clearance check does not model deformation, wear, thermal expansion, cable routing, surface roughness, or process capability unless those effects are represented separately. Treat it as geometric evidence for a defined model state, not a complete fit or reliability analysis.
Sources
Related terms
Interference detection
Interference detection is a CAD analysis that finds where selected nominal solid volumes overlap. It can locate a clash at a chosen assembly position, but a clean result does not prove adequate clearance, collision-free motion, or tolerance-safe fit.
Tolerance
A tolerance is the allowed variation from a nominal dimension, such as 10.00 ± 0.05 mm. Tolerances drive fit, cost, and inspection, and they have to be specified deliberately because a CAD model on its own stores only nominal sizes.
Assembly
An assembly is a CAD model made of multiple parts or subassemblies positioned relative to each other with mates or joints. Assemblies are where fit, clearance, interference, and motion get checked.
GD&T
GD&T is a symbolic language for specifying the allowed variation in a part's form, orientation, location, and runout relative to datum features. In the US it is defined by ASME Y14.5, and it tells the manufacturer and inspector which geometry actually matters for fit and function.