The surface strips in WIRE CUT EDM using molybdenum cutting wire electrode or brass wire electrode

High-speed WIRE CUT EDMstripes is obvious

EMD cutting process and EDM forming process are the same in that both of them are based on the principle of electrolytic corrosion during pulse discharge between the tool electrode and the workpiece electrode to instantaneously ablate the workpiece surface. However, the two processes are different in that EDM forming must be done with the shaped tool electrode which has precise dimension in advance, while wire-cutting does not require a shaped tool electrode. Instead, it uses a long electrode wire as a tool “cutting” according to the predetermined trajectory, like the woodworking saws used for sawing wood. Various complex parts are machined by this way (That is, curved surface formed by a straight line as a bus.). Therefore, as long as the electrode wire moves unevenly during machining or servo feeding is not balanced, certain cutting stripe will appear, more or less, which will affect the surface quality. This happens especially in HIGH SPEED WIRE CUT EDM, which molybdenum wire or brass wire(where to buy molybdenum cutting wire, see www.edm-taguti.com). The fast moving speed of the electrode wire, the inability to control the tension, and the non-stop commutation and direction changing, all will cause the instability of the electrode wire movement and servo feed, thus result in the frequent generation of cutting stripe， and it shows a black and white cross, the stripes are very obvious.

Although the LOW SPEED WIRE CUT EDM which normally do not use molybdenum wire also occasionally shows cutting stripes, the probability of streaking is small, and the stripe depth is not as deep as those generated by the HIGH SPEED WIRE CUT EDM.

Zeng Qian, Head of Quality Inspection Center for Special Machine tools in China, explained in details in his article published in (EDM) magazine issue 3 of 1998. See chart 6-1 below.

It can be seen that the strip depth formed by HS WIRE CUT EDM is obviously deeper than those formed by LOW SPEED WIRE CUT EDM

   6 -1 STRIPS resulted from WIRE CUT EMD

workpiece No.		1#	2#		3#	4#	5#		6#
machine model		CKX -2A				HC-6
EDM electrode material		molybdenum wire electrode				EDM Brass wire
WIRE CUTTING SPEED		HIGH SPEED WIRE CUT EDM				LOW SPEED WIRE CUT EDM
WIRE CUTTING SPEED ( m/ min)		600		4		3		0.8
EDM WIRE CUT Current and voltage		100 V				250 V
EDM WIRE CUT Working current		I. 7 A	I. 2A		0.5A	5.5 A	4.5A		0.3A
EDM Working fluid	category	JR-3A EDM emulsion				EDM DI water
	Electric resistivity	250/Ω . cm				4*104/Ω . cm
strip	WIRE CUT EDM Maximum depth	26.5 µm	17.5 µm		15.5 µm	22.5 µm	16.5 µm		15.0 µm
	WIRE CUT EDM black and white stripe	obvious				none

 

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