Impact resistance class – not a quality criterion for profiles

Differentiation according to impact resistance classes is not a basis for categorizing the quality of a profile.

EN 477 ‘Determination of the impact resistance of profiles using drop bolts’ is an established method for process monitoring in profile extrusion. If the impact does not lead to fracture, but is elastically cushioned by the profile wall, it can be concluded that the material is well plasticised. The EN 12608-1 profile standard specifies a classification system based on the drop height of the bolt.

However, whether or not this sudden load causes breakage still depends crucially on the geometry of the profile. This is because elastic cushioning of an impact is only possible if the wall that is hit has a sufficient span width.

As the requirements become more complex, geometries that require small spans width between the inner webs are also necessary. In addition, technically sensible cams and screw eyes on the outer walls can prevent the definition of a suitable impact point.  Despite good plastification, all of this would lead to breakage during testing. When developing a profile geometry, taking impact points into account can therefore be counterproductive.

Conclusion: Differentiation according to impact resistance classes is not a basis for categorising the quality of a profile. Due to this geometry dependency of the test, the profile standard also provides for this impact resistance test to be omitted (class 0).

Download EN