After a period of wire cutting, molybdenum wire will appear a section of black spots, black spots are usually several to tens of millimeters long, black spots are usually several to tens of centimeters apart.

 

The black spot is connected by arc discharge, burned and carbonized. It is easy to break after fining, crisp and carbonization. Black spots form black dots on silk tubes, and sometimes they also return black spots.

 

Arranged according to a certain percentage of patterns, known as "flower silk".

 

 

 

2. Why?

 

 

 

The continuous arc discharge is caused by the ineffective deionization, and a large amount of carbon is precipitated from the resistance heat of the arc to form carbon concentrate particles, and the molybdenum wire itself is carbonized. Workpiece thickness (discharge gap)

 

One of the three is "filament"

 

The basic conditions of the phenomenon. A "impurity" in the discharge gap (or inherent in the workpiece) that affects the spark discharge is the cause of the filament phenomenon. "Flower silk"

 

In the same way as spark discharge machining (EDM) arc burns, once the arc burns in the gap are formed, the workpiece and electrode will be ablated out of the pit and form carbon particles at the same time.

 

If carbon granules are not cleaned, they will not be able to continue processing. Fine carbon particles stick there, and there's going to be arc burns. They're getting bigger and bigger, and there's no way to eliminate them.

 

Ability. If the workpiece and electrode are displaced, both sides of the workpiece and the electrode will cause new arc burns, one of which will change in two places. The only way to do this is to clean up the people.

 

There's nothing we can do.

 

3, the occurrence and development of "filaments"

 

 

 

When the discharge gap is long, the removal of corrosion is difficult, the insulation ability is poor, and the spark explosion is weak, impurities are easily produced, and the resistance heat changes rapidly to arc burn.

 

Carbon concentrates are also mixed together. The arc point moves with the wire, during which each pulse energy is released through the arc point until the arc point comes out of the workpiece and insulates.

 

Only when it is possible to recover, is it possible to produce new spark discharge. The burn carbonization (black spot) of this point of molybdenum wire is formed. If the gap has just been induced by arc burning.

 

The point of the wound is still tenacious, and it is very easy to repeat the arc discharge with the molybdenum wire point in contact with the present, and the second burn carbonization (i.e. black spot) point is formed. So that's that.

 

The distance between a point and the workpiece exit is usually equal to the distance between two spots. Since the first burn carbonization, a carbonization point has been left on the wire, leaving a string of carbon in the workpiece gap.

 

Melting point, very fine carbon particles dispersed into the water at any time into the gap, they have become a "filament" trigger. It became "cross infection".

 

It is useless to change any of the water or workpieces, so that all the changes are useless. After a period of time, the "cross infection" inducing factors were gone.

 

Even the piece of material can cut again.

 

4, the performance and observation of "filaments"

 

 

 

Because of arc discharge, short circuit, open circuit and carbon particle formation, the current meter of the pulse source will swing sharply. The discharge spark will appear reddish, yellowed, and whitish. Early formation

 

The black spot is thickened by heat and carbonization, and passes through the gap and then becomes thinner after several times of ablation. For a period of time, heating and tension also make the black spot thinner. change

 

Brittle is caused by burning red and cooling and carbonization seriously. Because of the regular arrangement of flower spots on silk tubes, many people try to find patterns.

 

The result is not right from the circumference of the barrel, the circumference of the guide wheel, and the distance between the conductive block and the person. If there is a rule, it is the distance from the burn point to the workpiece exit.