近年來隨著精密模具及高效石墨模具（模具周期越來越短）的推出，人們對模具制作的要求越來越高，由于銅電極自身種種條件的限制，已越來越不能滿足模具行業的發展要求。石墨作為EDM電極材料，以其高切削性、重量輕、成形快、膨脹率極小、損耗小、修整容易等優點，在模具行業已得到廣泛應用，代替銅電極已成為必然。

    一、石墨電極(ji)材料特性

    1.CNC加(jia)工(gong)(gong)速(su)度快(kuai)、切削性高、修整(zheng)容易石(shi)(shi)墨機加(jia)工(gong)(gong)速(su)度快(kuai)，為銅電(dian)(dian)極(ji)(ji)(ji)的3～5倍，精加(jia)工(gong)(gong)速(su)度尤其(qi)突出，且(qie)(qie)其(qi)強度很高，對于(yu)超高（50～90mm）、超薄(bo)（0.2～0.5mm）的電(dian)(dian)極(ji)(ji)(ji)，石(shi)(shi)墨加(jia)工(gong)(gong)時不(bu)易變形。而且(qie)(qie)在很多時候，產(chan)品都需(xu)要有很好的紋面效果，這就要求在做電(dian)(dian)極(ji)(ji)(ji)時盡(jin)量做成整(zheng)體(ti)(ti)公電(dian)(dian)極(ji)(ji)(ji)，而整(zheng)體(ti)(ti)公電(dian)(dian)極(ji)(ji)(ji)制作時存在種種隱性清(qing)角，由于(yu)石(shi)(shi)墨的易修整(zheng)的特性，使得這一難題很容易得到解決，并(bing)且(qie)(qie)大大減少(shao)了電(dian)(dian)極(ji)(ji)(ji)的數量，而銅電(dian)(dian)極(ji)(ji)(ji)卻無法做到。

    2.快(kuai)(kuai)速(su)EDM成(cheng)形(xing)、熱(re)膨脹(zhang)小、損耗(hao)(hao)(hao)低(di)由于石墨的(de)(de)(de)導電(dian)(dian)(dian)性比(bi)(bi)銅(tong)好，所以(yi)它(ta)的(de)(de)(de)放電(dian)(dian)(dian)速(su)度比(bi)(bi)銅(tong)快(kuai)(kuai)，為(wei)(wei)銅(tong)的(de)(de)(de)3~5倍。且其放電(dian)(dian)(dian)時能承受(shou)住較大(da)電(dian)(dian)(dian)流，電(dian)(dian)(dian)火花粗加工(gong)時更為(wei)(wei)有利。同(tong)(tong)時，同(tong)(tong)等體(ti)積下，石墨重量(liang)為(wei)(wei)銅(tong)的(de)(de)(de)1/5倍，大(da)大(da)減(jian)輕EDM的(de)(de)(de)負荷(he)。對(dui)于制作大(da)型(xing)的(de)(de)(de)電(dian)(dian)(dian)極、整體(ti)公電(dian)(dian)(dian)極極具(ju)優勢(shi)。石墨的(de)(de)(de)升華溫(wen)(wen)度為(wei)(wei)4200℃，為(wei)(wei)銅(tong)的(de)(de)(de)3~4倍(銅(tong)的(de)(de)(de)升華溫(wen)(wen)度為(wei)(wei)1100℃)。在高(gao)溫(wen)(wen)下，變形(xing)極小（同(tong)(tong)等電(dian)(dian)(dian)氣條件下為(wei)(wei)銅(tong)的(de)(de)(de)1/3~1/5），不軟(ruan)化。可(ke)以(yi)高(gao)效、低(di)耗(hao)(hao)(hao)地將放電(dian)(dian)(dian)能量(liang)傳送到(dao)工(gong)件上。由于石墨在高(gao)溫(wen)(wen)下強度反(fan)而增(zeng)強，能有效地降低(di)放電(dian)(dian)(dian)損耗(hao)(hao)(hao)（石墨損耗(hao)(hao)(hao)為(wei)(wei)銅(tong)的(de)(de)(de)1/4），保(bao)證了石墨加工(gong)質量(liang)。

    3.重量(liang)輕、成本(ben)低(di)一套模具的(de)(de)制作(zuo)成本(ben)中，電(dian)(dian)(dian)極的(de)(de)CNC機加工時間(jian)(jian)、EDM時間(jian)(jian)、電(dian)(dian)(dian)極損耗(hao)等占總體(ti)成本(ben)的(de)(de)*大部分(fen)，而這些都(dou)(dou)是(shi)由電(dian)(dian)(dian)極材(cai)料本(ben)身所(suo)決定。石(shi)墨與銅相(xiang)比，石(shi)墨的(de)(de)機加工速度和EDM速度都(dou)(dou)是(shi)銅的(de)(de)3～5倍(bei)。同(tong)時，磨(mo)損極小的(de)(de)特性與整(zheng)體(ti)公石(shi)墨電(dian)(dian)(dian)極的(de)(de)制作(zuo)，都(dou)(dou)能減少(shao)電(dian)(dian)(dian)極的(de)(de)數量(liang)，也(ye)就(jiu)減少(shao)了電(dian)(dian)(dian)極的(de)(de)耗(hao)材(cai)與機加工時間(jian)(jian)。所(suo)有(you)這些，都(dou)(dou)可大大降低(di)模具的(de)(de)制作(zuo)成本(ben)。

    二(er)、石墨電極機電加(jia)工要求(qiu)與特點(dian)

    1.電(dian)極(ji)的(de)制作*的(de)石墨電(dian)極(ji)制作主要(yao)(yao)采用高速機(ji)床(chuang)來加(jia)工，機(ji)床(chuang)穩定(ding)性要(yao)(yao)好，三軸運(yun)動(dong)要(yao)(yao)均勻穩定(ding)不(bu)振動(dong)，而且像主軸這些回轉(zhuan)精度也要(yao)(yao)盡可能的(de)好。對一般的(de)機(ji)床(chuang)也可以完成(cheng)電(dian)極(ji)的(de)加(jia)工，只(zhi)是編(bian)寫刀路(lu)的(de)工藝與銅電(dian)極(ji)有所不(bu)同(tong)。

   ; 2.EDM放電(dian)加(jia)工石墨(mo)電(dian)極就是碳電(dian)極。因為石墨(mo)的(de)導電(dian)性能好，所以在放電(dian)加(jia)工中能節省大量時(shi)間，這也是用石墨(mo)做電(dian)極的(de)原因之(zhi)一。

    3.石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)電極(ji)的(de)(de)(de)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)特點工(gong)(gong)(gong)(gong)(gong)業用石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)質(zhi)硬而(er)脆，在(zai)CNC加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)時對刀(dao)具(ju)的(de)(de)(de)磨損(sun)較為(wei)嚴重，一般建議使用硬質(zhi)合金(jin)(jin)或金(jin)(jin)剛(gang)石(shi)(shi)(shi)(shi)涂層的(de)(de)(de)刀(dao)具(ju)。石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)在(zai)粗加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)時刀(dao)具(ju)可直接在(zai)工(gong)(gong)(gong)(gong)(gong)件上下刀(dao)，精加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)時為(wei)避免崩角、碎裂的(de)(de)(de)發(fa)生，常采用輕刀(dao)快(kuai)走的(de)(de)(de)方式加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)。一般而(er)言，石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)在(zai)切深小于0.2mm的(de)(de)(de)情況下很少發(fa)生崩碎，還會獲得較好的(de)(de)(de)側壁表(biao)面質(zhi)量。石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)電極(ji)CNC加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)時產生的(de)(de)(de)灰塵(chen)比較大，可能入侵到機(ji)(ji)床(chuang)的(de)(de)(de)導軌絲桿和主軸等，這(zhe)就要(yao)求石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)機(ji)(ji)床(chuang)有(you)(you)相應的(de)(de)(de)處理石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)灰塵(chen)的(de)(de)(de)裝置，機(ji)(ji)床(chuang)密封(feng)性也要(yao)好，因(yin)為(wei)石(shi)(shi)(shi)(shi)墨(mo)(mo)(mo)有(you)(you)毒。