Questions and Answers about Wire Electric Discharge Machining [EDM]

How to set the setting cutting conditions ?
How to change the optimization of cutting conditions?
What should you do if you have a problems and troubleshooting?

How to set the setting cutting conditions ?

Setting cutting conditions (to increase cutting speed)

(Example) Tuning of Mitsubishi W-EDM machine

Parameters for W-EDM machines of respective manufacturers

W-EDM machine makers	Discharge energy setting	Off-time setting
GF Machining Solutions (formerly Agie)	P, T	TD
GF Machining Solutions (formerly Charmilles)	A, IAL	B, Aj
Seibu	I	OFF
Sodick	IP, ON	MA, OFF
Fanuc	VM, ON	OFF
Makino	Peak current, ON	OFF
Mitsubishi	IP	SB, OFF

Reference: How much the electrical discharge energy can be raised depends on the material thickness.

Superior cutting conditions may be achieved by changing the settings according to the material thickness described below.

Material thickness	Setting point
20mm or less	- Basically, lesser electrical discharge power is required for thinner workpiece. - A significant increase in speed is not allowed with thinner plates, for which acceleration is limited to being low. - The amount of discharging energy allowed to increase for material with a thickness of 10 mm or less is also small.
20-60 mm	- If the condition of a high-pressure jet stream is good, the machining efficiency will be improved. - For cutting a flat plate, place the nozzle as closely to the plate as possible. - A further increase in discharge energy is possible, given the better discharge of cutting sludge.
60mm or more	- Generally, more wire is consumed and susceptible to breaking more with a thicker plate. - The cutting speed may be increased by raising the wire speed. - Significant changes in conditions are possible, as the EDM wire shows a significant difference from brass wire in this range of thickness.

Note: As an optimal setting point varies depending on actual cutting conditions and other factors, please review the above-mentioned items so as to match the settings regarding your specific situation.
Please contact us if you have any questions.

How to change the optimization of cutting conditions?

Optimization of cutting conditions (Example) In case of an W-EDM machine manufactured by Mitsubishi

Case of rough cutting (1st cut)

How to change cutting conditions
(In case of cutting AISI D2, 60 t with φ0.2 wire *For a reference only. [AE: 21 notches, SE: 1 notch used])

1. In case of each workpiece

			Standard value	Adjustment value
Types of material			AISI D2 DIN 1.2363	AISI P25 DIN 1.2330	AISI 1045 DIN C45	Stainless steel	Aluminum	Copper	Tungsten carbide copper tungsten	Graphite
Voltage switching	Vo	(Notch)	12	0	0	0	0	0	0	+4
Cutting setting	IP	(Notch)	9	0	-1	0	0	-1	-1	-2
Off-time	OFF	(Notch)	1	0	0	0	0	0	0	0
Stabilizer A	SA	(Notch)	3	0	0	0	0	0	0	-2
Stabilizer B	SB	(Notch)	10	+2	+2	+2	+3	0	0	+4
Wire tension	WT	(Notch)	8	0	0	0	0	0	0	-1
Average cutting voltage	VG	(V)	39	0	0	+2	0	+8	+5	+15
Actual cutting speed	FA	(%)	100	90	85	85	200	85	50	40

2. In case of each cutting purpose

			Standard value	Correction value
Types of material			AISI D2 DIN 1.2363	Either nozzle separated	Both nozzle separated	Stepped workpiece	Taper 3 degrees	Taper 5 degrees	Taper 10 degrees	Taper 15 degrees
Voltage switching	Vo	(Notch)	12	0	0	0	0	0	0	0
Cutting setting	IP	(Notch)	9	-1	-1	-2	0	0	-2	-2
Off-time	OFF	(Notch)	1	0	0	0	0	0	0	0
Stabilizer A	SA	(Notch)	3	0	0	0	0	0	0	-1
Stabilizer B	SB	(Notch)	10	+2	+2	-1	+2	+2	+3	+3
Wire tension	WT	(Notch)	8	0	0	0	-1	-1	-2	-3
Average cutting voltage	VG	(V)	39	0	+4	+4	0	+5	+5	+10
Actual cutting speed	FA	(%)	100	80	60	60	90	85	70	50

*Wire breaking can be reduced by raising the SE notch from 1→2→3→4→5.

Improvement of cutting precision (For punch shape)

When seams are formed on cutting surface

Tips on finish cutting (points to be checked during cutting)

What should you do if you have a problems and troubleshooting?

Problems and troubleshooting

Trouble	Phenomenon	Cause	Check item/Solution
1. Wire breaking	①Breaking near feed plate	Feed plate in friction	Check the feed plate and replace it periodically.
	①Breaking near feed plate	No striking of water from the feed plate nozzle	Clean the feed plate nozzle and check water pressure.
	②Breaking near wire guide	Dirty wire guide	Perform periodic maintenance.
		Excessively strong holding force of the wire guide	Make adjustment for optimal holding force.
		Misaligned wire guide	Reset positioning accuracy.
	③Breaking when idling	Poor wire hooking	Check wire hooking position.
	③Breaking when idling	Wire winding crossed (tangled, passing beneath another)	Replace or wind off wire.
	④Breaking immediately after the start of cutting or within 5 mm	Air mixed in the cutting liquid (breaking in air)	Degrease and wash the object subject to cutting, as cutting conditions are very strict.
		Tilted object subject to cutting	Check water pressure of machining liquid.
			Start cutting after plumbing.
	⑤Breaking after cutting 5 mm or more	Low pressure of cutting liquid	Check for positioning error of cutting liquid nozzle and wear.
		Mismatched cutting conditions	Check for dirt of suction opening of cutting liquid supply tank.
		Existence of foreign material or pinhole within the object	Check the cutting liquid evacuation route when cutting an object in a complex shape.
		Defective wire	Replace wire.
		Poor travel of wire	Check for friction, cracks, and dirt of urethane rubber roller.
			Correct setting error of wire tension.
2. Error of cutting accuracy	①Shaping defect	Insufficient pressing force of wire guide and positioning error	Adjust pressing force of wire guide and position.
		Insufficient wire tension	Properly set wire tension.
		Large fluctuation in ambient temperature	Remove material distortion (stress).
		Non-uniform cutting materials	Erroneous plumbing of wire.
		Improper offset	Clean and maintain guide dies and associated components.
3. Error of surface accuracy	①Rough surface	Mismatched cutting conditions (non-uniform electric discharge)	Increase wire transfer speed.
	②Wire mark on cutting surface	Insufficient wire tension	Increase cutting speed.
	③Unstable cutting speed	Excessively slow cutting speed	Replace ion-exchange resin and stabilize water specific resistance.
		Degraded ion-exchange resin	Clean and maintain the wire travel system (i.e., guiding system).
		Traveling fault of wire	Clean, maintain, and check consumption of the power feeder.
		Friction, crack or dirt of urethane roller
		Improper wire tension
4. Faulty cutting speed	①Increase of cutting speed disabled	Mismatched cutting conditions (improper material, workpiece thickness, or size)	Match cutting conditions with those listed in the instruction manual.
4. Faulty cutting speed	①Increase of cutting speed disabled		Check positions and wear of upper and lower nozzles.
5. Curl failure	①Irregular storage of wire within the scrap box (wire running wild to form permanent waves)	Uneven remnant stress of wire	Increase applied current by 1 TAP (higher cutting speed).
		Uneven wear of conveyor roller belt	Replace wire when uneven wear occurs or wear exceeds 1/3 of wire diameter.
		Positioning error of conveyor roller belt	Consult with maintenance contractor of W-EDM machine.
		Improper pressing force of conveyor roller belt	Run wire with pressing force suitable for wire used.
		Large irregularity in wire shape	Replace the wire with one from a lot having proper straightness.
6. Failure of automatic threading (insertion failure)	①Disabled automatic insertion into guidance and pilot hole	Contamination and clogging existing in guidance	Perform periodical maintenance.
		Improper (too small) diameter of pilot hole (on working side)	Check minimum lower hole diameter of W-EDM machine.
		Insufficient jet water pressure and amount of water	Adjust water pressure valve manually.
		Misaligned upper head and pilot hole	Perform program checking and centering.
		Large irregularity in wire shape	Replace the wire with one from a lot having proper straightness.
7. Failure of automatic threading (cutting failure)	In case of cutter cutting	Uneven wear and insufficient cutting force of cutter	Replace wire if a wire mark exists, and check pressing pressure of cutting.
	①Poor cutting result	Blurred cutting end of wire	Replace the cutting cutter with a new one.
	②Not inserted into lower hole	Large irregularity in wire shape	Replace the wire with one from a lot having proper straightness.
	In case of annealer cutting	Erroneous entry of wire diameter	Match the wire material and characteristics recommended by the W-EDM maker.
	①Poor cutting result	Improper wire material	Enter the diameter of the wire being used.
	②Varied cutting positions	Wrong wire type
8. Faulty winding (wire passing beneath another)	①Wire end passing beneath another	Released wire end (human error)	Thoroughly check the wire for passing beneath another after rewinding.
8. Faulty winding (wire passing beneath another)	②Wire passing beneath another occurs in the middle of a spool stroke, even though there is no problem when running	Released wire end (human error)	The customer needs to properly handle the wire end (when setting spool to W-EDM machine).
9. Winding failure (loose winding)	①Loose winding and "playing" wire	Erroneous adjustment of winding tension (unstable dancer)	Set winding tension for individual wire diameters.
		Play due to vibration of rewinding machine	Securely install the machine.
		Misaligned center of the spool on the rewinding machine	Verify the shape and setting state of the spool on the machine.
10. Faulty winding (uneven winding)	①Uneven (i.e., convex and concave) winding in sections close to spool flanges	Erroneous adjustment of rewinding machine traverser	Adjust traverser and perform periodical checking when rewinding.
		Deformed spool	Change return control motor.
			Bring traverse pulley as close to winding body diameter as possible.
			Check spool shape.