Simulating real-life robbery attempts, testers at Swiss thermoformer Plastika Balumag AG, swing fire axes and sledgehammers at thermoformed moneyboxes for up to 30 sec to determine whether plastics can thwart thieves when steel cannot.
Steel moneyboxes were easily pried apart at riveted seams. According to Reto Bamert, managing director at Plastika, thermoformed polycarbonate and high-impact ABS failed as well, as both materials are notch sensitive. However, boxes thermoformed of Kydex 100 withstood the 30 sec of abuse from the axe-wielding testers.
Kydex is a proprietary thermoplastic that provides impact resistance of 960 J/m, modulus of elasticity of 2,307 N/mm2, and tensile strength of 42 N/mm2. The material, from Kleerdex Co., Bloomsburg, Pa., carries fire-retardant ratings of UL Std 94 V-0 and 5V, and is more transparent than polycarbonate and high-impact ABS to frequencies emitted by GPS transmitters in each money box. The exterior of the box is thermoformed of 4.7-mm Kydex sheet, and of 2-mm thick material for the interior. Before the parts are joined, a net is positioned between them, and a GPS antenna is affixed to the interior. Profile strips of 9.4-mm-thick material are welded to exterior edges to strengthen the box base and lid and then deburred. The thermoformed boxes are seeing use in France, Sweden, Norway, and Germany.