In general, EDM is widely used in precision cavity mold manufacturing. The so-called mirror EDM generally refers to the surface roughness Ra < 0.2um, the machined surface has the effect of mirror reflection. Mirror EDM has practical significance for some precision machining to replace manual polishing process and improve the quality of parts.

不是所有型腔都可以进行镜面电火花加工

Not all cavities can be machined by mirror EDM

放电加工之所有能达到镜面效果，与放电加工中产生的碳黑层有直接的关系。如果加工部位能容易形成均匀的碳黑层，也就是意味着容易加工出镜面效果。

The mirror effect of EDM is directly related to the carbon black layer produced in EDM. If the processing part can easily form a uniform carbon black layer, it means that it is easy to process the mirror effect.]

（1）简单形状比复杂形状的电火花加工要容易获得镜面。容易获得镜面效果的形状是圆形。复杂形状的拐角、弧面处镜面效果稍差。

(1) It is easier to obtain the mirror surface for simple shape EDM than for complex shape EDM. The shape that is easy to get the mirror effect is round. The mirror effect of complex shape corner and arc surface is slightly poor.

（2）底面比侧面更容易获得好的镜面效果。深度越大的型腔，越难得到镜面加工效果，尤其是侧面。

(2) It is easier to get good mirror effect on the bottom than on the side. The larger the depth of the cavity, the more difficult to get the mirror processing effect, especially the side.

（3）加工面积越大，越难以获得好的镜面效果。

(3) The larger the processing area is, the more difficult it is to obtain good mirror effect.

（4）开口部位、型腔的中空部位镜面效果欠佳。

(4) The mirror effect of the open part and the hollow part of the cavity is not good.

不是所有的模具钢材都可以进行镜面电火花加工

Not all die steel can be mirror EDM

有些模具钢材的电火花加工能容易达到镜面效果（如NAK80），而有些模具钢材无论如何也达不到镜面效果（如SKD11）。同时，模具钢材的硬度高些，电火花加工镜面的效果更好。请参考下表各种材料与镜面加工性能。

Some die steel EDM can easily achieve the mirror effect (such as NAK80), while some die steel in any case can not achieve the mirror effect (such as SKD11). At the same time, the hardness of die steel is higher, and the effect of EDM mirror is better. Please refer to the table below for various materials and mirror processing performance.