0910 CIM of Catamold BASF陶瓷粉末注射成型准则.docx

1、0910 CIM of Catamold BASF陶瓷粉末注射成型准则Catamold Feedstock for Powder Injection Molding - Guidelines for processing CIM feedstock 催化成型(Catamold)射料用於粉末注射成型 陶瓷粉末注射成型的射料使用準則Release : 14th/July/2009 From BASE web資料來自德國巴斯夫網站Translator of Chinese中文譯者Notes : Blue text 注解: 藍色文字Blue text is special note for Chine

2、se readers from the translator Dr.Q. 藍色文字為譯者Dr.Q對中文讀者提供的特別注解。Dr. Qiu Yaohung (Dr. Q), VP and GTO of Chenming Electronic Technology Co., Ltd (company web site: ). Dr. Q is one of student of Professor Lin (Dr. S.T. Lin, Paul. He is a professor of the Department of Mechanical Engineering Technology, Na

3、tional Taiwan University of Science and Technology). Professor Lin was one of student of Professor R.M. German. Dr.Q is a technical adviser of MIM-CN alliance (MIM China alliance) also. 邱耀弘博士(Dr. Q), 台灣晟銘電子科技有限公司技術長。Dr.Q為林舜天教授(Dr. S.T. Lin, Paul，國立台灣科技大學機械工程技術系教授)的大弟子，林教授則是Dr. R.M. German的弟子之一。Dr. Q

4、亦兼任中國金屬粉末注射聯盟(MIM-CN)的技術顧問。1. Introduction 簡介Powder Injection Molding (PIM, Ceramic: CIM, Metal: MIM, Cermet:CMIM) is a process which offers advantages over conventional production methods for small parts with complex shapes or large production numbers. Starting from fine ceramic or metallic powders

5、, a homogeneous feedstock is produced by mixing with a thermoplastic binder. The thermoplastic binder serves to combine in one manufacturing process the shaping capability that is well known from polymeric materials with the also well-established powder sintering technology. After the molding stage

6、the shaped parts are liberated of the binder and the remaining powder preshape is then sintered to a high density part. 粉末注射成型(PIM, 陶瓷:CIM, 金屬: MIM, 瓷金: CMIM)是有別於過去傳統製程，提供產品一種小而複雜、產量需求大的快速製程。不論採用金屬或是陶瓷粉末，將之與熱塑性塑膠材料的黏結劑均勻的混合成為射料(Feedstock中國地區習慣稱為：喂料)，熱塑性黏結劑與粉末充分混合後，作為一貫化的注射過程中用來塑造產品形狀之能力是眾所周知的，同時也是在粉

7、末燒結上熟知的技術。在成型完成以後的階段，部分的黏結會分解釋放，剩餘的部份則維持其它固體粉末的預形狀(通常是等比例放大的形狀，所以用Preshape來表示)，然後經過燒結到達高密度零件。The Catamold feedstock is based on a Polyacetal binder, a semi-crystalline thermoplastic material with good processing characteristics, high dimensional stability, high rigidity and good warm strength. This

8、excellent property profile makes Polyacetals the preferred material in demanding applications like precision mechanics, but these advantages can be exploited in PIM equally well. 催化成形技術是運用聚甲醛作為黏結劑的基礎，它是一種半結晶熱可塑性聚合物，適合成形並能有安定的尺寸、高剛性和高溫強度。這種優異的性能使聚甲醛成為要求苛刻的應用之首選材料，如精密機械的塑膠零件，同樣的，也可以利用這些優勢在PIM製程上。Howev

9、er, the decisive advantage of Polyacetal as a binder for Catamold feedstock is the ability for rapid catalytic binder removal. In the presence of a suitable catalyst Polyacetal can be depolymerised far below the melting point to yield the gaseous constituent monomer. Thus catalytic debinding allows

10、binder removal from the molded shape by a controlled, smooth development of gas from the solid binder along the lines of a shrinking unreacted core model. A small amount of residual binder, necessary to confer a certain strength for handling to the remaining powder preshape, is then easily eliminate

11、d in the early stages of a conventional sintering cycle.然而，聚甲醛類作為催化成形射料的粘合劑，其決定性的優勢是能夠快速以硝酸催化而分解的粘合劑。在合適的催化劑存在下，聚甲醛類可以在遠低於熔點的溫度分解，成為氣體成分的單體。因此，催化脫脂過程允許黏結劑從模造生坯中可控制性的移出，從固體的表面以平滑且線性的移出率直到固體的中心處，而保持固體原有的造型。少量的殘留黏合劑，則要賦予的目標是用於幫助其它粉末維持預形狀的強度，然後在常規的燒結程序上，在早期階段很容易的燒除。The processing properties of the highl

12、y loaded Catamold ceramic feedstock in the injection molding, de-binding and sintering steps are discussed in the following chapters. 高固體負載的催化成形陶瓷射料用在注射成形的加工性能，包含結合及燒結步驟，在下面的章節中會逐一討論。2. Injection Molding 注射成形Compared with plastics, Catamold has a higher thermal conductivity, a higher density and a h

13、igher viscosity. These differences must be taken into account before choosing the molding machine, designing the mold and during prosing. 跟塑膠比起來，催化成形射料有著高熱傳導性、高密度與較高的黏度(因為陶瓷粉末的形狀多角且表面電性非中性，對於射料的黏度造成提高之影響)，因此對於注射成形機、模具設計、乃至於製程設計都和以前所有的認知有所不同。2.1. Injection molding machine 注射成形機For the production of c

14、eramic parts by Ceramic Injection Molding using the BASF Catamold line of products normal hydraulic or electric injection molding machines with open nozzles can be used. Electric machines, having a faster control feedback loop, may offer advantages in critical applications due to the control during

15、injection and hold stages. A reversal of the direction of flow due to inexact control in the critical solidification stage may be the precursor to a planar particle stacking fault and this will be detrimental to the integrity of the sintered part. 對於陶瓷零件的生產採用BASF射料以陶瓷注射成型生產時，以全液壓或電動注射成型機搭配開放式噴嘴裝備，是可

16、以被採用的。電動注射成形機，具有更快的控制反應與反饋迴路，可以提供關鍵應用的優勢，因為在注射過程中的控制和保壓階段，由於不精確的控制使射料在凝固階段有回彈的可能，造成固體粒子堆積層錯位分離的狀況，這將不利於燒結部件的完整性。A low compression three zone screw (compression ratio 1 : 1.6 preferrably, maximum 1 : 2) is recommended, for Catamold TZP grades only 1 : 1.6. Choose a screw where the shot volume matches

17、 the plasticising capacity reasonably well, otherwise the excessively long residence times may lead to binder degradation which is witnessed by the appearance of gas bubbles. Screw diameters of 18 -25 mm are common. 一種三區低壓縮螺桿是被推薦的(螺桿壓縮比為1：1.6是首選，最大不超過1：2)，正方晶多晶氧化鋯(Tetragonal Zirconia Polycrystal, TZ

18、P)之催化成形射料等級只能使用1：1.6。選擇一個適合的螺桿攸關停留在其上處的每一注射體積和其塑化能力，停留時間過長，可能會導致塑料燒焦並降解產生氣泡的外觀，這是很容易觀察到的。18-25毫米的螺桿直徑是常見的，也是適當的規格。The clamp force is determined by the size of the part to be injected, but the majority of CIM parts are relatively small (1 -10 mm) and 25 -50 tons clamp force will cover the majority. 鎖

19、模力量必須決定於注射零件的尺寸。但是CIM零件通常相對的小(110mm)，因此以2550噸的鎖模力都足夠用在此製程。Wear protection should be present in the form of a through hardened screw and a hardened cylinder liner. High production numbers (several 100.000 shots) may need an all-tungsten carbide plasticising unit. 螺桿的螺紋和活塞必須考慮磨耗的保護，尤其是產量大的產品生產時(超過數十萬次

20、的注射)建議以全碳化鎢材質作為塑化區的螺桿考量。2.2 Mold design模具設計Before starting mold construction some thought must be given to the position of parting line, ejector pins and gate. These are unavoidable features of a mold, they will leave a visible remnant on the sintered part and should be positioned there where they d

21、o not matter or where they can be easily removed. 開模具之前必須要考慮零件的分模線、頂針與注入口的位置。這些不可避免的模具特徵，都會在燒結之後出現在留下痕跡，所以在設計之初就必須考慮其重要性，是否影響外觀而是否放在容易去除的位置。(其實就是要先以製造可行性設計 Design for Manufacturing , DFM報告來作檢討和分析)Weld lines can be, particularly for alumina, the precursor to a locally weakened surface in the sintered

22、 part and may extend up to 0.1 mm below the surface. If the function of the part does not allow this sort of imperfection, the position of the gate should be changed or the cavity needs multiple gating to shift t ition and/or reduce the size of the defect. 結合線會造成缺陷的，它的出現會造成氧化鋁零件燒結後的表面強度局部變弱，甚至延伸至表面下

23、方0.1mm。如果零件不允許這類缺陷影響產品功能時，進膠點的位置應該被改變或是此模穴需要多點進膠來改善，試著將缺陷移位或減少缺陷的大小。Since the viscosity of Catamold is higher than of most thermoplastic materials, the pressure drop in the gating system should be reduced as much as possible: 由於催化成形射料的黏度遠大於傳統的熱塑性塑膠料，必須儘可能控制並降低整個進膠系統內的壓力： Runners as short as possible

24、. 澆道儘可能短 Runner cross section as large as possible; 4mm is the usual compromise. 澆道截面積要儘可能大，通常至少要有4mm是最為普遍 Runner cross section round. 澆道必須是圓形的截面 Avoid sharp bends. 避免急轉彎 Hot runners are troublesome due to inaccurate temperature control, but rewarding to reduce pressure loss and cycle time. 熱流道的麻煩在於

25、溫度控制不準確的故障發生(改用溫度回饋補償式可以改善)，但優點是可以減少注射壓力損失和週期時間。The gate should fulfill the following criteria: 進膠點要符合以下的條件： Uniform mold filling. 均勻的填滿模穴 As large as possible to minimise pressure drop 儘可能開大以減少射壓損失 Position at the thickest section. 位置設定在最厚的斷面 Direct the jet of melt along or against a wall or pin. 可

26、直接注射熔融射料沿著或靠著牆或頂針。Design of the mold essentially follows the guidelines for thermoplastics: CIM的模具設計基本上可遵循熱塑性塑料注射模具的指導方針： Avoid unnecessary and abrupt differences in wall thickness. Jetting problems and air entrapment are encouraged. 避免不必要的突增壁厚差異，以減少紊流問題和殘留空氣。 Use stiffening ribs instead of thick wa

27、lls. 零件多使用加強筋或肋，取代厚實的牆壁。 Core out thick sections. 模仁之核心避免具有厚實的斷面(熱傳導不佳易蓄熱) Avoid sharp corners. Use at least 0.3 mm radius. 模穴內零件避免尖角，使用半徑至少為0.3mm圓角 Symmetrical pressure application for long and thin parts or round sections. 對長而薄的部件或圓形斷面，模穴必須要應用均勻且對稱的壓力設計(包含模穴對稱性的設計如單穴/2穴/4穴/6穴/8穴，所有澆道系統都要同時考慮)。 Goo

28、d venting (depth 0.01 -0.02 mm) at the end of the flow path is essential and also there where air is trapped. Supplementary ejector pins are useful to vent pockets of air. 好的模穴末端排氣(深度0.01-0.02mm)是必要的，包含容易將空氣困住的地方。利用補充的頂針可增加有效的排氣路徑。 Contact of flow fronts far off the gate may form a weak spot (weld l

29、ine). Venting is again essential. 遠離進膠點的射料流末端，可能會形成一個弱點(焊接線產生位置)。排氣仍是必要不可少的設計。 If more than one flow front move away from the gate, one of them usually comes to a halt, cools, hardens and causes an inhomogeneous zone. 如果有一個以上的射料流遠離進膠點，其中一股通常會停止，冷卻、變硬導致不均勻的區域出現。(儘可能讓所有射料流同時填滿模穴，同時停止流動！) Carefully bal

30、ance multi-cavity tools (i.e. simultaneous cavity filling), otherwise tolerance and possibly quality differences occur. Do not consider more than four cavities for high tolerance or difficult parts. 小心平衡多腔模具(即同步腔填充)，否則可能發生產品允差和質量差異發生。當允差要求很嚴格的產品時，不考慮以超過四個以上的模穴。De-molding: 脫模設計 A taper of 0.5 -1 shou

31、ld be provided for surfaces in the demolding direction.These surfaces should be polished. 請盡量設計有0.51的拔模角作為脫模順利的輔助特徵。表面要盡量拋光。 For other surfaces a fine eroded quality is usually sufficient and improves the ventilation. Mirror quality cavity surfaces promote sticking problems and binder segregation. 通

32、常略為有細咬花(晒紋)的表面有助於模面強度，也可以改善排氣問題，鏡面品質的模穴表面會有促進黏著和粘結劑分離的問題，除非必要不需要使用到鏡面品質的模穴表面(成本考慮呀！)。 Be generous with ejector pins. Use large pins or profile ejectors on thin sections. 慷慨的頂出吧！使用大的頂出銷或整面頂出設計針對薄切片斷面的大面積產品。Mold temperature control is one of the most important parameters in processing of Catamold: 使用催化成形射料時要注意到的模溫控制參數： Use a thermally insulating plate between mold and clamp plate. 模具和注射機的模板之間要絕熱墊片阻隔熱量流失。 A uniform temperature (+/-2C) must be provided. This needs to be obeyed in particular for multi-cavity tools, otherwise tolerance and quality differ