Table 1.

Design of Experiment of the extrusion process and the resulted responses (for all runs the spheronisation process was constant with 9 min time, 75% speed and 15 g load).

Run	Pattern	Screw Design	Screw Speed [rpm]	Hopper Speed 1 [rpm]	mc [%]	Roundness	Roughness	py SD	uy [%]
1	100	L1	200	260	23.87	3	2	0.08	91.62
2	1+−	L1	300	250	23.86	3	4	1.19	91.18
3	1−−	L1	100	250	23.79	2	4	0.41	86.62
4	1++	L1	300	270	21.70	3	2	0.23	95.79
5	100	L1	200	260	23.55	3	3	0.12	98.12
6	1−+	L1	100	270	21.39	3	2	0.23	97.53
7	200	L2	200	260	23.15	2	2	0.36	98.04
8	2−−	L2	100	250	24.09	5	4	1.3	0
9	2+−	L2	300	250	22.78	4	4	0.56	42.42
10	2++	L2	300	270	21.85	3	3	0.26	95.96
11	200	L2	200	260	22.12	3	2	0.65	97.49
12	2−+	L2	100	270	22.78	3	2	0.22	96.43

¹ Hopper speed set to 250, 260 and 270 resulted in a feed rate of 5.8 g/min, 6.2 g/min and 6.6 g/min. mc = moisture content; py = process yield; uy = useable yield.