The services of the Kiwa Italia Plastic Materials Laboratory, accredited LAB No. 0001L by ACCREDIA, are aimed at manufacturers of plastic tubes of circular cross-sectional material who need to verify (under extreme operating conditions) that the declared characteristics meet the requirements of the Reference Standards.
The impact test defined in accordance with Standard UNI EN ISO 3127 is also referred to as impact testing by the Watch Face Method. The specimens to be tested are usually conditioned at very low temperatures. During the test, the are subjected to blows from a free-falling dart, of mass and shape specified by the reference standard, thrown from a predetermined height toward a given point along the circumference of the tube under test.
The True Impact Rate (TIR), referred to as the TIR, of the tested lot is estimated in this way. The TIR is determined as the ratio, as a percentage, of the total number of ruptures to the total number of impacts, where a rupture is defined as any crack or split, visible to the naked eye, within the tube under test, caused by impact with the free-falling dart. In case dents are present these should not be considered as ruptures.
The same test can be performed following a different method: the Ladder Method. The latter is governed by Standard UNI EN ISO 11173. During an impact test using the Ladder Method, specimens are subjected to a single blow from a dart with a specified mass and shape. The free fall height of the dart is determined by setting a sequence of different heights and strikes at a random location along the circumference of the tube. When the number of breaks equals the number of non-breaks the test can be considered finished, determining H50, defined as the average drop height.
Both methods are performed during production control of a given product. They thus allow verification under extreme operating conditions that the characteristics meet the requirements of the Reference Standards.