火花機加(jia)工(gong)(gong)是(shi)放(fang)電加(jia)工(gong)(gong)，工(gong)(gong)具(ju)電極和工(gong)(gong)件之間(jian)并(bing)不直接(jie)接(jie)觸，而是(shi)有(you)一(yi)個火花放(fang)電間(jian)隙，這個間(jian)隙一(yi)般是(shi)在0.05~0.3mm之間(jian)，有(you)時可能達到0.5mm甚至更大。間(jian)隙中充滿工(gong)(gong)作液，加(jia)工(gong)(gong)時通過(guo)高壓脈(mo)沖(chong)放(fang)電，對(dui)工(gong)(gong)件進行放(fang)電腐蝕，加(jia)工(gong)(gong)過(guo)程中沒有(you)宏觀切削力(li)。

電(dian)火花放電(dian)時，局部、瞬時爆炸力的(de)(de)平均(jun)值很(hen)小(xiao)，不足以(yi)引(yin)起工(gong)件(jian)的(de)(de)變(bian)形和位移(yi)，可(ke)(ke)以(yi)“以(yi)柔(rou)克剛”。由(you)于鼎拓電(dian)火花加工(gong)直接(jie)利(li)用電(dian)能(neng)和熱能(neng)來去(qu)除金屬(shu)材料，與工(gong)件(jian)材料的(de)(de)強度(du)和硬(ying)度(du)等關系不大，因此可(ke)(ke)以(yi)用軟的(de)(de)工(gong)具電(dian)極(ji)加工(gong)硬(ying)的(de)(de)工(gong)件(jian)，實現“以(yi)柔(rou)克剛”。

火花機加工(gong)(gong)(gong)可(ke)以加工(gong)(gong)(gong)任何難加工(gong)(gong)(gong)的(de)(de)金屬材(cai)料(liao)(liao)(liao)和導(dao)電(dian)材(cai)料(liao)(liao)(liao)，由于(yu)加工(gong)(gong)(gong)中材(cai)料(liao)(liao)(liao)的(de)(de)去除是靠放(fang)電(dian)時的(de)(de)電(dian)、熱作用實現的(de)(de)，材(cai)料(liao)(liao)(liao)的(de)(de)可(ke)加工(gong)(gong)(gong)性(xing)主要取決于(yu)材(cai)料(liao)(liao)(liao)的(de)(de)導(dao)電(dian)性(xing)及熱學特性(xing)，如熔點、沸(fei)點、比(bi)熱容、導(dao)熱系數(shu)、電(dian)阻率等(deng)，而幾乎與(yu)其(qi)力學性(xing)能(硬(ying)度(du)、強(qiang)度(du)等(deng))無關，這樣(yang)可(ke)以突(tu)破(po)傳統切削加工(gong)(gong)(gong)對刀具的(de)(de)限制，可(ke)以實現用軟(ruan)的(de)(de)工(gong)(gong)(gong)具加工(gong)(gong)(gong)硬(ying)、韌的(de)(de)工(gong)(gong)(gong)件甚至可(ke)以加工(gong)(gong)(gong)聚晶金剛行、立方(fang)氮化硼一類的(de)(de)超硬(ying)材(cai)料(liao)(liao)(liao)，目前電(dian)極材(cai)料(liao)(liao)(liao)多采用紫銅或石墨(mo)，因此(ci)工(gong)(gong)(gong)具電(dian)極較(jiao)容易加工(gong)(gong)(gong)。

火花機加(jia)工(gong)(gong)(gong)可以(yi)加(jia)工(gong)(gong)(gong)形(xing)狀復(fu)雜(za)(za)的表面，由(you)于(yu)可以(yi)簡單地將工(gong)(gong)(gong)具(ju)電極的形(xing)狀復(fu)制到(dao)工(gong)(gong)(gong)件上，因此特(te)別適用于(yu)復(fu)雜(za)(za)表面形(xing)狀工(gong)(gong)(gong)件的加(jia)工(gong)(gong)(gong)，如復(fu)雜(za)(za)型腔模(mo)具(ju)加(jia)工(gong)(gong)(gong)等，特(te)別是數控(kong)技術的采用，使(shi)得用簡單的電極加(jia)工(gong)(gong)(gong)復(fu)雜(za)(za)形(xing)狀零件成(cheng)為(wei)現實。