标题: 塑膠注塑件的斷面狀況評估--懂塑胶的同学进来 [打印本页] 作者: 菜鸟 时间: 2011-10-27 13:41 标题: 塑膠注塑件的斷面狀況評估--懂塑胶的同学进来 Plastic parts which are likely to be exposed to mechanical stress (bending) due to the mechanic design of the application must not have a fraction behaviour that can result in any injuries.
Bend the plastic parts or the final products in various directions. These bending movements are intended to cover normal use, as well as unusual directions and overloading. Example: overbend a headband so far that the two ear cups get in touch.
It is essential to inspect the fracture of the plastic part. A good result is when the plastic part has ductile behaviour (not breakage Usually it can be bent several times in the same position until it completely breaks (white discoloration ? called “stress whitening”
The result is not acceptable when brittle fractures are present. Brittle fractures can be seen if a plastic part immediately breaks at the first bending movement (or overbending movement) without having deformed fractures. An extreme case is if multiple brittle fractures occur at this test.