Meaning
Determination of the exact spatial position of a workpiece or mold insert using the minimum number of physical constraints avoids over-constraint and improves assembly accuracy. Utilizing kinematic registration ensures that the part is positioned repeatably without relying on friction or tight slip fits that can wear out over time. This technique employs a system of six points of contact to restrict all six degrees of freedom of the component.
In polymer moulding, this is often implemented in high-precision modular mold inserts and assembly fixtures.
Fixture Design
Mechanical fixtures utilizing three V-grooves and three spherical pins provide a classic configuration for achieving high precision. Through kinematic registration, any thermal expansion or contraction of the plastic part is accommodated without shifting the center point of the assembly. This design prevents the build-up of internal stresses that can warp thin-walled molded enclosures during assembly or testing.
Moulding Accuracy
Precision molded parts often require secondary operations such as laser marking or ultrasonic welding. If the part is not held in a stable position, these operations will occur in the wrong location, resulting in scrap. Applying kinematic registration to the nesting fixtures ensures that every molded part sits in the identical position regardless of minor variation in part shrinkage or operator loading technique.
Repeatability Benefit
The elimination of mechanical play in the fixture prevents translational and rotational errors across high-volume production runs. This use of kinematic registration reduces the standard deviation of part dimensions, ensuring that critical interfaces remain within their specified tolerances.
