Table 1.

Combination of process parameters for tungsten carbide (a) and brass (b) electrodes based on Central Composite Design (CCD).

(a)				(b)
Tool Type	Tungsten Carbide			Tool Type	Brass
	Peak Current (I)	Voltage (V)	Frequency (F)		Peak Current (I)	Voltage (V)	Frequency (F)
	(index)	(V)	(kHz)		(index)	(V)	(kHz)
WC1	40	110	83	BR1	26	120	130
WC2	30	100	90	BR2	40	100	110
WC3	50	100	90	BR3	40	140	110
WC4	30	120	90	BR4	40	100	150
WC5	50	120	90	BR5	40	140	150
WC6	40	93	100	BR6	60	120	96
WC7	23	110	100	BR7	60	86	130
WC8	40	110	100	BR8	60	120	130
WC9	57	110	100	BR9	60	154	130
WC10	40	127	100	BR10	60	120	160
WC11	30	100	110	BR11	80	100	110
WC12	50	100	110	BR12	80	140	110
WC13	30	120	110	BR13	80	100	150
WC14	50	120	110	BR14	80	140	150
WC15	40	110	117	BR15	94	120	130