Anisotropic Shrinkage Variance in Glass-Filled Polyamide Secondary Tooling Nests
Secondary tooling nests for glass-filled polyamide accommodate anisotropic shrinkage through floating datum pins aligned with transverse contraction vectors.
CMM Holding Fixture
Meaning
Precision metrology tool secures a moulded part in a repeatable and known position for dimensional inspection. A cmm holding fixture allows for the measurement of flexible or complex geometries that cannot be held by hand. The base of the device is typically made from aluminum or a stable composite.
Alignment Orientation
Correct positioning relative to the machine axes is achieved through a system of locators and clamps. When a cmm holding fixture is used, the part is held in its functional orientation to simulate how it will fit in the final assembly. This setup ensures that the measurement data is relevant to the engineering requirements.
Precise positioning reduces the time needed for the probe to find the part features.
Measurement Stability
Errors caused by part movement or vibration are eliminated when the component is properly restrained. Because the cmm holding fixture provides a rigid platform, the coordinate measuring machine can run at higher speeds without losing accuracy. The design of the fixture must allow the probe to access all critical surfaces without interference.
This often requires the use of standoff pillars and angled clamps. High quality fixtures are built to the same tolerances as the parts they hold. This level of precision is necessary for validating high capability processes.
Reliability Factor
Consistency between different operators and different machines is a hallmark of a good gauge. Using a cmm holding fixture ensures that every part in a batch is measured from the exact same starting point. Reliable data collection supports the statistical process control efforts.