Figure 9.4 shows an immediate jump for both the controller and the thermocouple. The thermocouple maxes out at 322 C within 10 s, and the controller at 278 C within 30 s. Both the thermocouple and controller stabilize within 3 min. As previously noted, the thermocouple stabilizes at a higher temperature (286 C) than the controller (270 C). This test was completed to determine the time required for the pre-heat furnace to stabilize if the operator chose to adjust the temperature by at least 10 . 9.2.2 Annealing Furnace The purpose of the annealing furnace is to raise and hold the temperature of the sample to the applicable testing temperature while in μ-g or hyper-g depending upon the test matrix. The sample will be in this furnace for the duration of the desired gravity level (μ-g/hyper-g). The annealing furnace was characterized in the same manner as the pre-heat furnace. Figure 9.5 shows the annealing furnace ramp from room temperature to a set point of 280 C. As seen in Fig. 9.5, the temperature quickly jumps up to above the set point, but eventually levels out to the desired temperature. The thermocouple reads a higher temperature initially (325 C) but eventually settles down to just above the set point (288 C). The controller reaches the set point within 3 min for the thermocouple; the set point is never reached but stabilizes within 6 min. The next step in characterizing the annealing furnace was to increase the temperature by 20 . This would show how quickly the furnace would adjust to a small temperature change. Figure 9.6 shows the annealing furnace ramp from 280 C to the new set point of 300 C. 250 260 270 280 290 300 310 320 330 0 100 200 300 400 500 600 700 800 900 100 Temperature (C) Time (sec) Pre-Heat Furnace Ramp from 260C to 270C Controller Thermocouple Fig. 9.4 Pre-heat furnace ramp from 260 to 270 C Annealing Furnace Ramp from 26C to 280C Temperature (C) 0 50 100 150 200 250 300 350 0 100 200 300 400 500 600 700 800 900 1000 Times(sec) Controller Thermocouple Fig. 9.5 Annealing furnace ramp time from 26 to 280 C 70 A.S. Torres et al.
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