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Protective shields used for machine tools are intended to prevent tools and machined parts from being
catapulted out of the working zone of the machine and to protect persons from getting injured by flying
objects. A central prerequisite for constructing such protective shields, is the use of sufficiently
shock-resistant materials.
CEN/TC 143 has suggested a test method for determining the shock resistance qualities of materials and
established a list of suitable protective devices ready for use. This method was primarily designed to meet
the requirements of turning lathes, which are particularly hazardous because of the high kinetic energy of
the rotating chuck and the work piece. The test method is described along with the test results. The
latter show comparable shock resistance characteristics for 3-mm-thick steel metal sheets made from the
traditional material St 12.03 on the one hand and 8-mm-thick polycarbonate on the other. Especially
polycarbonate is a perfect material for window shields because of its high energy absorption capacity;
towards the working zone, however, it should be combined with a glass shield to protect it against
mechanical damage and the effects of cooling lubricants. Shock resistance increased with the material
thickness.
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