What are the Reasons Why Graphite Electrode is Easy to Accumulate Carbon?

Aug. 12, 2021

As a Graphite Electrodes Supplier, share it with you.

1. Improper use of processing regulations, exceeding the current density  tolerance of the discharge section, and the pulse interval is too small

The application of discharge energy is not arbitrary. If you want to process faster, apply a larger current. In the electrical discharge machining regulations, it generally refers to the peak current, that is, the current flowing through the discharge channel when the pulse is on, and the current acting time Very short, depending on the pulse on time, that is, the pulse width. The current value displayed by the ammeter or analog ammeter on the processing equipment is the average value of the pulse current, because the pulse is intermittent discharge. Generally speaking, the peak current is determined by the number of power amplifier components in the discharge circuit and the voltage applied by the circuit, and has nothing to do with the pulse width and pulse interval. In addition to the peak current, the processing current can also be adjusted by adjusting the pulse width and pulse width. Change from time to time. as the picture shows.

Graphite Electrodes

Graphite Electrodes

The discharge current density of the graphite electrode is about 6-8 (A)/cm2. If this value is exceeded, the probability of abnormal discharge will increase, and the probability of carbon deposit will also increase.

The correct method is to correctly estimate the discharge area and select the processing parameters according to the discharge area.

For example, there is a square electrode with a discharge area of 3×3 (mm). When selecting discharge parameters, first select the model number condition of □3, and then select a suitable initial processing condition according to the amount of electrode reduction.

It must be noted here that the discharge current should be estimated according to the discharge area. The normal current value of this area should be controlled at about 1/9 of the current density value, and it can be increased appropriately. It is better not to exceed 2.5A, which is too large. If so, it is easy to produce carbon deposits. Therefore, for some small electrodes, there is no need to reduce the size of the electrode too much. As in the above example, the electrode shrinkage of 0.1 on one side is basically sufficient.

2. Poor chip removal

A. The influence of processing depth

The smaller the discharge cross-sectional area and the deeper the machining depth, the more difficult it is to remove chips. For this type of cavity machining, improving the quality of chip removal is the key. When it comes to EDM chip removal, there are currently two conventional methods, one is the immersion method, the other is the immersion method, and the other is the immersion method in the immersion process to improve the fluidity of the liquid. To enhance the chip removal effect. In terms of machining accuracy and chip removal effect, the liquid immersion method is much better than the pure liquid method. The chip removal mechanism of the liquid immersion method is to use the high-speed movement of the spindle to cause the cavity to be in a high pressure or vacuum state. The strong turbulence of the liquid achieves the purpose of chip removal. Imported equipment, due to the extremely high acceleration of the spindle, is very suitable for this chip removal method, and the effect is very good. The flushing type processing method, due to the uneven flow direction and pressure, the chip removal may not be complete. Where the chips are collected, it is easy to form two electric discharges, which affects the accuracy of the cavity; secondly, it is easy to cause carbon deposits. Where conditions permit, immersion processing methods should be used as far as possible for processing. Our company also has Graphite Electrodes on sale, welcome to contact us.

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