Testing Machines and Systems for Metals - Zwick - #49

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49 Application During assembly of a materials testing machine it is normal practice to incorporate the high-temperature unit directly into the machine. This type of arrangement allows tensile tests to be carried out at both ambient and raised temperatures. During testing at ambient temperature, components such as the high-temperature furnace, hightemperature extensometer and pullrod are simply swung out of the test area. Using a centrally divided folding furnace allows the pull-rod in use to remain in the machine. After the rod has cooled down it can be removed via a quick-change system. 4.10 High-Temperature Testing Accessories The high-temperature system consists of three main components: • The swivel-mounted hightemperature furnace • The high-temperature extensometer, which can also simply be swiveled out of the test area. It is moved up to the specimen directly via a slit in the furnace: • The pull-rod, comprising connecting pieces for the quickchange system and the pull-rod itself, via which the tensile load is transmitted into the furnace, and the specimen grips at the end of the pull-rod. In practice the most common specimens are threaded-end specimens, as described in DIN 50125 . Flat specimens are produced from thin sheets and are held in positive-fitting flat-specimen grips. Standardized specimen grips in various materials are available for these specimens in the temperature range up to 1200 °C. Standardized units are also available for compression and flexure tests up to 1600 °C. The volumes present in the furnace, the temperature tolerances and hold-times specified in the standard; these plus heating and cooling times mean that the duration of tests is more or less fixed - and decidedly time-consuming. To shorten specimen throughput time, systems with several furnaces are available from the standard range. Fig. 1: Materials testing machine with hightemperature furnace Fig. 2: Quick-change system for hightemperature pull-rods Fig. 3: Temperature controller Fig. 4: Positive-fitting high-temperature specimen grips for flat specimens