TIPS ON USING ENVIRONMENTAL CHAMBERS AND FURNACES

If your system incorporates “specimen protect” or “load protect” (Instron® 3400, 5500/5500A, 5800, 5900, 6800, 8500 and 8800 Series electronics), you can use this feature to compensate for load string and specimen expansion/contraction while your furnace or chamber reaches set-point temperature.

Having inserted the specimen into the grips, set the desired load threshold value and enable the feature before switching on the furnace or chamber. As the load string expands or contracts, the crosshead or actuator will move to keep the force on the specimen below the threshold value.

• To prevent loss of heat around pull rods and push rods, always use any convection shields provided, or lightly pack the space between the pull rod and the furnace or chamber port with a suitable refractory fiber.

• Make sure you use the recommended anti-seize compounds and lubricants on your grips to help aid specimen removal.

• Use the smallest grips possible in order to reduce heat-up times and maximize the available travel in an environmental chamber.

• After you have finished testing at below ambient temperatures, you can remove any condensation from the grips and pull rods by warming them in the chamber and allowing them to cool naturally.

• Remember to allow sufficient time for the specimen to reach the test temperature after inserting it into the grips. Consider putting a number of specimens in the chamber to reach the test temperature, provided the different thermal history that results is not significant. This will also help to improve testing productivity.

• Ensure that ALL load string components are rated for use at the required test temperature. Certain items such as rubber-coated jaw faces have reduced temperature ranges compared to the rest of the load string. The chamber may be capable of exceeding the temperature rating of the load string, so ensure that temperature limits and alarms are set accordingly.

• For optimum window clarity during low temperature testing, always switch on the window heaters (if fitted) for 40 minutes prior to running your tests. This is especially important when using non-contacting extensometry to ensure reliable target tracking.