Fractography

Surface Interpretation

High resolution imaging of the break site confirms if the breakdown originated from a structural flaw or an external load. Resin properties such as molecular weight and additive concentration modify the texture of these surfaces. Moulders compare observed failure patterns against known standards to distinguish between base resin degradation and processing errors.

Brittle failure occurs when molecular chains lack sufficient mobility, while signs of yielding suggest the material reached its elongation limit before separation.

Production Analysis

Injection parameters including hold pressure and cooling time determine the residual internal stresses stored in the matrix. Fractography identifies specific processing defects like gate vestige weakness or improper weld line fusion through the shape and orientation of surface features. Regrind integration increases the concentration of impurities, which alters the crack path and creates distinct topography on the fracture face.

Part specifications often mandate specific surface characteristics to prevent premature fatigue in high cycle applications.

Material Validation

Datasheet values represent the performance of pristine samples under ideal conditions rather than the behavior of an actual molded geometry. Fractography provides the only mechanism to verify that the manufactured part maintains the integrity required by its service environment. Testing confirms that environmental stress cracking, which appears as crazing on the surface, differs from mechanical fatigue by its interaction with chemical agents.

Analytical evidence from these examinations provides the final determination regarding the root cause of component failure.