3.1.2. The Steepest Climbing Test

The design scheme and results of the steepest climbing test are presented in Table 4. The relative error was the value between the simulated stacking angle and the measured stacking angle (51.15◦). The stacking angle gradually increased with the arrangement order of the test groups, and the relative error presented as first decreasing and then increasing. The stacking angle and relative error of the No.2 run were 51.07◦ and 0.16%, respectively. It indicated that the most optimal parameter level range was around the No.2 test, which was chosen to be the intermediate level (0) in the Box–Behnken test design. Additionally, the parameter levels of No.1 and No. 3 were chosen as the low (−1) and high levels (+1).


**Table 4.** Design scheme and results of steepest climbing test.

Note: positive effects (B and J) were in ascending order, and negative effects (D and E) were in descending order.
