滾(gun)塑制(zhi)品(pin)有時會出(chu)現一些制(zhi)品(pin)的(de)缺陷，那么一般來說我們該(gai)如何將這(zhe)些缺陷解決(jue)呢？

1、氣泡或孔洞?

(1)成因分(fen)析(xi)

          時(shi)模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)內(nei)的(de)(de)(de)物料在(zai)(zai)受(shou)熱(re)(re)過(guo)程(cheng)中，隨模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)的(de)(de)(de)轉動(dong)(dong)(dong)(dong)逐漸熔(rong)(rong)融、流(liu)(liu)動(dong)(dong)(dong)(dong)、粘(zhan)附在(zai)(zai)熱(re)(re)的(de)(de)(de)模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)內(nei)表面(mian)(mian)(mian)，模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)內(nei)部(bu)(bu)(bu)空(kong)(kong)氣(qi)(qi)(qi)(qi)受(shou)熱(re)(re)體(ti)(ti)(ti)(ti)積膨脹，氣(qi)(qi)(qi)(qi)壓(ya)升(sheng)高(gao)，通(tong)(tong)過(guo)通(tong)(tong)氣(qi)(qi)(qi)(qi)孔逐漸向模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)外(wai)部(bu)(bu)(bu)流(liu)(liu)動(dong)(dong)(dong)(dong)，直至模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)內(nei)外(wai)空(kong)(kong)氣(qi)(qi)(qi)(qi)壓(ya)力平衡，反之亦然。同時(shi)，模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)型腔(qiang)內(nei)保持著一定壓(ya)強(qiang)。在(zai)(zai)樹(shu)脂熔(rong)(rong)融致密化的(de)(de)(de)過(guo)程(cheng)中，滯(zhi)留在(zai)(zai)粉末顆(ke)粒之間的(de)(de)(de)氣(qi)(qi)(qi)(qi)體(ti)(ti)(ti)(ti)被擠向塑料熔(rong)(rong)體(ti)(ti)(ti)(ti)的(de)(de)(de)自由(you)表面(mian)(mian)(mian)，但(dan)由(you)于熔(rong)(rong)體(ti)(ti)(ti)(ti)表面(mian)(mian)(mian)張力的(de)(de)(de)存(cun)在(zai)(zai)，氣(qi)(qi)(qi)(qi)體(ti)(ti)(ti)(ti)不(bu)足以脫(tuo)離(li)熔(rong)(rong)體(ti)(ti)(ti)(ti)表面(mian)(mian)(mian)易形(xing)成(cheng)(cheng)(cheng)氣(qi)(qi)(qi)(qi)泡(pao)，從而形(xing)成(cheng)(cheng)(cheng)制品(pin)內(nei)表面(mian)(mian)(mian)的(de)(de)(de)氣(qi)(qi)(qi)(qi)泡(pao)和外(wai)表面(mian)(mian)(mian)的(de)(de)(de)氣(qi)(qi)(qi)(qi)扎，嚴(yan)重情況(kuang)下形(xing)成(cheng)(cheng)(cheng)較大(da)的(de)(de)(de)孔洞(dong)(dong)”。如(ru)果熔(rong)(rong)體(ti)(ti)(ti)(ti)流(liu)(liu)動(dong)(dong)(dong)(dong)性好(hao)、模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)升(sheng)溫(wen)速率慢、模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)通(tong)(tong)氣(qi)(qi)(qi)(qi)孔通(tong)(tong)暢，則熔(rong)(rong)體(ti)(ti)(ti)(ti)中的(de)(de)(de)氣(qi)(qi)(qi)(qi)體(ti)(ti)(ti)(ti)可以順利地逸出，反之則熔(rong)(rong)體(ti)(ti)(ti)(ti)中的(de)(de)(de)氣(qi)(qi)(qi)(qi)體(ti)(ti)(ti)(ti)易滯(zhi)留形(xing)成(cheng)(cheng)(cheng)制品(pin)缺陷(xian)。當模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)合(he)模(mo)(mo)(mo)(mo)(mo)(mo)不(bu)嚴(yan)，模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)加熱(re)(re)過(guo)程(cheng)中型腔(qiang)中的(de)(de)(de)一部(bu)(bu)(bu)分氣(qi)(qi)(qi)(qi)體(ti)(ti)(ti)(ti)會(hui)通(tong)(tong)過(guo)合(he)模(mo)(mo)(mo)(mo)(mo)(mo)部(bu)(bu)(bu)位(wei)(wei)的(de)(de)(de)縫隙(xi)向模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)外(wai)部(bu)(bu)(bu)流(liu)(liu)動(dong)(dong)(dong)(dong)，致使存(cun)模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)相應部(bu)(bu)(bu)位(wei)(wei)的(de)(de)(de)產品(pin)內(nei)部(bu)(bu)(bu)產生氣(qi)(qi)(qi)(qi)孔或氣(qi)(qi)(qi)(qi)泡(pao)；在(zai)(zai)模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)冷卻過(guo)程(cheng)中，如(ru)果模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)閉(bi)合(he)不(bu)嚴(yan)，斟模(mo)(mo)(mo)(mo)(mo)(mo)其(qi)內(nei)外(wai)存(cun)在(zai)(zai)空(kong)(kong)氣(qi)(qi)(qi)(qi)壓(ya)力差，空(kong)(kong)氣(qi)(qi)(qi)(qi)會(hui)通(tong)(tong)過(guo)合(he)模(mo)(mo)(mo)(mo)(mo)(mo)部(bu)(bu)(bu)位(wei)(wei)(分型面(mian)(mian)(mian)處)的(de)(de)(de)間隙(xi)進入(ru)模(mo)(mo)(mo)(mo)(mo)(mo)其(qi)內(nei)，在(zai)(zai)制品(pin)的(de)(de)(de)外(wai)部(bu)(bu)(bu)產生氣(qi)(qi)(qi)(qi)孔。孔洞(dong)(dong)的(de)(de)(de)形(xing)成(cheng)(cheng)(cheng)還(huan)與(yu)粉末顆(ke)粒的(de)(de)(de)形(xing)狀(zhuang)有關。當聚(ju)乙(yi)烯(PE)粉末顆(ke)粒帶有細長尾巴或呈(cheng)毛發(fa)狀(zhuang)時(shi)，在(zai)(zai)堆(dui)積過(guo)程(cheng)中會(hui)形(xing)成(cheng)(cheng)(cheng)搭橋，滯(zhi)留較多的(de)(de)(de)空(kong)(kong)氣(qi)(qi)(qi)(qi)。特(te)別是(shi)在(zai)(zai)模(mo)(mo)(mo)(mo)(mo)(mo)具(ju)(ju)(ju)(ju)(ju)的(de)(de)(de)拐角處，粉末的(de)(de)(de)搭橋會(hui)導致較大(da)的(de)(de)(de)孔洞(dong)(dong)形(xing)成(cheng)(cheng)(cheng)。

 (2)、解決(jue)方案

         調(diao)整通氣(qi)(qi)管或(huo)(huo)起相同作(zuo)用(yong)的(de)(de)(de)金屬亂絲(si)卷(juan)制(zhi)的(de)(de)(de)長(chang)(chang)條至模(mo)具(ju)(ju)內(nei)(nei)(nei)部(bu)適(shi)當距離。通氣(qi)(qi)管一般采(cai)(cai)用(yong)薄壁(bi)的(de)(de)(de)金屬氟塑料(liao)管，其直(zhi)徑由制(zhi)品(pin)(pin)尺寸(cun)和物料(liao)性(xing)(xing)能(neng)決定。(一般薄壁(bi)制(zhi)品(pin)(pin)按每立(li)方米(mi)模(mo)具(ju)(ju)設定10—12?mm孔徑)，管子長(chang)(chang)度根據制(zhi)品(pin)(pin)型腔(qiang)深度應保(bao)證其末端伸(shen)入到(dao)模(mo)腔(qiang)中心或(huo)(huo)到(dao)合適(shi)位置。為避(bi)免模(mo)具(ju)(ju)旋轉時樹脂粉(fen)末從排(pai)氣(qi)(qi)口溢出，通氣(qi)(qi)管內(nei)(nei)(nei)要用(yong)玻璃絲(si)、鋼絲(si)絨、石墨粉(fen)等充填。模(mo)具(ju)(ju)適(shi)當緩慢升(sheng)溫(wen)、提高(gao)爐溫(wen)(熔(rong)融(rong)溫(wen)度)或(huo)(huo)延(yan)長(chang)(chang)加熱時間(jian)(jian)，確保(bao)物料(liao)充分熔(rong)融(rong)和氣(qi)(qi)體排(pai)出。在模(mo)具(ju)(ju)內(nei)(nei)(nei)表面涂(tu)(tu)覆特氟龍(聚四氟乙(yi)烯)涂(tu)(tu)層替代各(ge)種脫模(mo)劑，保(bao)持(chi)模(mo)具(ju)(ju)內(nei)(nei)(nei)部(bu)干(gan)燥。如(ru)果是嵌件因(yin)素影響，可對(dui)嵌件及其周圍部(bu)分區域進(jin)行預熱。在產(chan)品(pin)(pin)、模(mo)具(ju)(ju)設計過(guo)程(cheng)中，充分考慮以下有(you)利于消除氣(qi)(qi)泡(pao)或(huo)(huo)氣(qi)(qi)孔的(de)(de)(de)措施：采(cai)(cai)用(yong)熔(rong)體流動速率(MFR)較(jiao)高(gao)的(de)(de)(de)物料(liao)、采(cai)(cai)用(yong)密(mi)度較(jiao)低的(de)(de)(de)物料(liao)、改善模(mo)具(ju)(ju)壁(bi)厚均(jun)勻性(xing)(xing)、延(yan)長(chang)(chang)自然冷卻時間(jian)(jian)、延(yan)緩噴霧(噴水)冷卻、制(zhi)品(pin)(pin)上的(de)(de)(de)凸筋或(huo)(huo)突(tu)出部(bu)位不(bu)宜(yi)過(guo)窄或(huo)(huo)過(guo)高(gao)(對(dui)應于模(mo)具(ju)(ju)上的(de)(de)(de)凹槽(cao)不(bu)能(neng)太窄、太深)等。

2、樹脂包(bao)覆不良

(1)、成(cheng)因(yin)分析

           上(shang)一(yi)般有許多金(jin)屬鑲嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)，通過滾(gun)(gun)塑形成制(zhi)品(pin)(pin)上(shang)的(de)(de)(de)(de)一(yi)部(bu)分，以增(zeng)強制(zhi)品(pin)(pin)局部(bu)度(du)。在滾(gun)(gun)塑時(shi)，嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)相當于模具(ju)上(shang)的(de)(de)(de)(de)一(yi)部(bu)分，使(shi)(shi)得(de)此處模具(ju)壁(bi)厚增(zeng)加，嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)末端(duan)不(bu)(bu)易獲得(de)與(yu)模具(ju)同(tong)(tong)樣的(de)(de)(de)(de)溫度(du)，導致(zhi)(zhi)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)上(shang)的(de)(de)(de)(de)樹脂包(bao)覆(fu)不(bu)(bu)良(liang)(liang)(liang)。尤其(qi)(qi)是大(da)型(xing)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)，如果嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)結(jie)構(gou)設(she)計(ji)不(bu)(bu)合理，使(shi)(shi)得(de)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)傳(chuan)(chuan)熱(re)性能(neng)不(bu)(bu)良(liang)(liang)(liang)，不(bu)(bu)能(neng)獲得(de)與(yu)模具(ju)同(tong)(tong)樣的(de)(de)(de)(de)溫度(du)，更(geng)易導致(zhi)(zhi)樹脂涂覆(fu)不(bu)(bu)均或達(da)不(bu)(bu)到設(she)計(ji)要求，降低嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)與(yu)制(zhi)品(pin)(pin)結(jie)合的(de)(de)(de)(de)強度(du)。旋轉(zhuan)滾(gun)(gun)塑成型(xing)的(de)(de)(de)(de)轉(zhuan)速通常(chang)較(jiao)(jiao)低，不(bu)(bu)同(tong)(tong)于制(zhi)作鑄型(xing)尼(ni)龍產品(pin)(pin)的(de)(de)(de)(de)離心(xin)澆鑄，嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)相對制(zhi)品(pin)(pin)表面太(tai)高時(shi)出現樹脂包(bao)覆(fu)不(bu)(bu)良(liang)(liang)(liang)的(de)(de)(de)(de)幾率更(geng)高一(yi)些。一(yi)般來說嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)上(shang)的(de)(de)(de)(de)塑料(liao)壁(bi)厚與(yu)制(zhi)品(pin)(pin)壁(bi)厚差(cha)別很(hen)大(da)，這(zhe)(zhe)與(yu)滾(gun)(gun)塑時(shi)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)傳(chuan)(chuan)熱(re)性能(neng)不(bu)(bu)良(liang)(liang)(liang)和嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)太(tai)厚有直接關系(xi)。嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)的(de)(de)(de)(de)位置太(tai)靠近制(zhi)品(pin)(pin)相鄰的(de)(de)(de)(de)側表面時(shi)，由于嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)阻(zu)擋(dang)了(le)物料(liao)的(de)(de)(de)(de)流動，會導致(zhi)(zhi)此處物料(liao)堆積(ji)少或嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)與(yu)側喪向不(bu)(bu)能(neng)完全搭(da)橋(qiao)，制(zhi)品(pin)(pin)易出現較(jiao)(jiao)大(da)孔(kong)洞或嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)包(bao)覆(fu)不(bu)(bu)嚴的(de)(de)(de)(de)缺陷。特別指出的(de)(de)(de)(de)是，嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)具(ju)有較(jiao)(jiao)好的(de)(de)(de)(de)傳(chuan)(chuan)熱(re)性能(neng)不(bu)(bu)僅就其(qi)(qi)材料(liao)本身(shen)而言，其(qi)(qi)結(jie)構(gou)也應使(shi)(shi)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)具(ju)有較(jiao)(jiao)好的(de)(de)(de)(de)傳(chuan)(chuan)熱(re)性能(neng)，如空(kong)腔不(bu)(bu)能(neng)太(tai)大(da)或滾(gun)(gun)塑時(shi)設(she)法(fa)用金(jin)屬封堵(du)大(da)的(de)(de)(de)(de)空(kong)腔，在設(she)計(ji)大(da)型(xing)嵌(qian)(qian)(qian)件(jian)(jian)(jian)(jian)(jian)時(shi)尤其(qi)(qi)要考慮這(zhe)(zhe)一(yi)點。

(2)、解決(jue)方案(an)

          使嵌(qian)件具有良好的傳(chuan)熱結構，盡量消除不利于嵌(qian)件傳(chuan)熱的因素。??在滿(man)足條(tiao)件(jian)(jian)和(he)嵌件(jian)(jian)強(qiang)度(du)(du)(du)需求(qiu)的前提(ti)下，嵌件(jian)(jian)相(xiang)對制品(pin)表面高度(du)(du)(du)和(he)體積(ji)盡量小。嵌件(jian)(jian)上的止轉或防拉槽的深度(du)(du)(du)和(he)寬度(du)(du)(du)與滾(gun)塑要求(qiu)相(xiang)適宜。滾(gun)塑時，視情況(kuang)對嵌件(jian)(jian)進行預(yu)熱(re)會取得比(bi)較良好的效果，對大型嵌件(jian)(jian)尤其有效