鋁合金由於3C產業的蓬勃發展之下，3C外殼材料往往需具備高品質之表面、精緻的外觀、高強度保護殼、良好的導熱性、環保再利用之特性等，然而為了提高鋁合金表面的防護力、裝飾性、功能性，最常用的表面處理製程為陽極氧化處理。陽極氧化處理製作鋁合金外殼常會遇見一些表面缺陷，如陽極剝落、色澤暗沉不均、表面蝕孔、表面色差等缺陷，對於陽極所產生表面色差缺陷提出針對性探討。
本論文主要研究主題為:以澆鑄參數來改善陽極後表面色差缺陷，取陽極色差缺陷之批號鋁錠間進行比對測試，測試結果發現有部分鋁錠可觀察出表面存在大量的白色斑點，經查驗白色斑點之鋁錠與澆鑄模台相對位置皆偏向澆鑄冷端區。進行澆鑄中模台溫度量測，冷熱端溫度大，最大溫度差可達40℃以上，由此可見模台均溫性不佳，且整體溫度皆偏低。此研究內容會針對澆鑄中模台上鋁湯溫度來進行探討，並朝向設備及製程的參數問題來改進。
本研究內容利用田口方法進行製程實驗，提出可能改善白色斑點的澆鑄組合參數，找出解決陽極後條紋色差缺陷的方法。用L18直交表作為實驗設計，分別選用七個控制因子，包括熔爐溫度、除氣箱溫度、澆鑄速度、保持時間、冷卻水量、鋁湯充模方式、模台預熱時間之參數設計作為關鍵因素進行測試。
在進行田口實驗後結果得出在澆鑄參數中的，鋁湯充模方式(Filling Mode)與熔爐溫度(Furnace Temp.)，相互搭配下，可以提升模台中所有模穴之均溫性，並提升整體澆鑄溫度。
另外在進行效果驗證實驗中，使用Type-B充模方式搭配較高的熔爐溫度(745℃) ，可明顯改善澆鑄區冷端之溫度，且整體澆鑄溫度大於680℃。進行後續分析及小批量生產，鋁錠試片無白色斑點情況發生，生產出成品無明顯色差缺陷。試量產出不良率統計，不良率平均以原本5%改善至0.95%。
藉由模台尾端(冷端)充湯及洩湯方式，在未改變前起鑄之熱端及冷端溫度最大之溫度差約40℃，改變後可把起鑄熱端及冷端溫度差縮至30℃，而兩者對於生產最大的差異，需損耗尾端所洩掉之鋁湯約110kg。澆鑄初期因模台溫度未達熱平衡狀態，且初期冷端冷區分佈範圍較廣，以利用充湯方式改變冷端冷區的分佈，讓尾端吸取熱量且可將所有模穴較快得到熱平衡，將冷區分佈範圍縮小。其熔爐溫度為主要影響澆鑄整理溫度表面之因子，在設定溫度越提升表現越佳，使模台上之鋁湯整體溫度更高，且較容易控制模台上溫度變化。而澆鑄速度進行田口實驗發現在S/N比反應圖上雖無明顯差異，在澆鑄為主要目的是影響鋁棒內部結構，且澆鑄速度會直接影響熔湯供給的速率，間接造成熱場溫度變化為不可忽略之參數。針對澆鑄溫度製程改善白色斑點上可以有比較明確的方向來進行改善。

Due to the rapid development of the 3C industry, the developed trend of 3C products is light, thin, and small. The grade requirement of 3C housing materials is increasing, including appearance, strength, thermal conducting and so on. Aluminum alloys have become the mainly considered materials. The most common surface treatment methods for aluminum alloys are anodizing and dyeing. The anodized aluminum alloy shell often has some surface defects, such as anode chipping, dark and uneven color, surface pitting, surface chromatic aberration, etc. In the thesis, the relationship between anodizing chrominance defects and aluminum billets is investigated. A large quantity of white spots are found in the sampled aluminum billets at the cold port of casting zone. For solving the white-spot problems, the performance of aluminum melt on the mold table is explored by measuring the temperatures of the melt on the mold. The maximum temperature difference between hot and cold ports is up to 40 °C. It can be seen that the temperature uniformity of the mold table is not good, and the overall temperature is low. In the work, the Taguchi method is used to carry out the experimental study for obtaining the parameter design to improve the temperature uniformity and to increase the overall temperature of the aluminum melt. The parameter design could help to solve the white-spot problem, resulting in the anodizing defects of aluminum alloy housing.

參考文獻
[1] 尤惠法,“ 3C機殼廠技術創新過程之關鍵成功因素”,國立中山大學管理學院, 民國九十四年六月

[2] 吳忠春、蘇武忠、楊政峰、洪雅秀、陳韋志,“ AA7XXX系鋁合金經陽極處理後之表面缺陷觀察與分析”,南臺科技大學機械工程系, 2017年3月

[3] Chunlei Wang, Mingxing Wang, Benhai Yu, Dong Chen, Ping Qin, Minghai Feng, Qirun Dai,“The grain refinement behavior of TiB2 particles prepared with in situ technology”, Materials Science and Engineering A, vol. 459, pp.238-243, 2007.

[4] Hanliang Zhu, Xinquan Zhang, Malcolm J. Couper, and Arne K. Dahle,“Effect of Initial Microstructure on Surface Appearance of Anodized Aluminum Extrusions”, Metallurgical and Materials Transactions A, vol. 40, pp.3264-3275, 2009.

[5] 賴昆男、陳彥勳、蔡孟村,“鋁錠DC澆鑄缺陷改良技術研究”,遠東科技大學機械工程研究所,2011年7月

[6] 孝雲禎、馬宏聲,“有色金屬熔鍊與鑄錠[M] ”,東北大學出版社，1994。

[7] Wolfgang Schneider, “D.C. Casting of Aluminum Alloys - Past, Present And Future”, Essential Readings in Light Metals pp 534-541, 2002

[8] S. Jones, A. K. Prasada Rao, Z. Fan,“Melt Conditioned Direct Chill (MC-DC) Casting of Al Alloys”, Indian Institute of Metals, vol. 66, pp.117-121, 2013.

[9] Miha Založnik, Arvind Kumar, Hervé Combeau, Marie Bedel, Philippe Jarry, Emmanuel Waz,“The Coupling of Macrosegregation with Grain Nucleation, Growth and Motion in DC Cast Aluminum Alloy Ingots”, Essential Readings in Light Metals pp 848-853, 2011

[10] D. A. Granger, John F. Grandfield, Dmitry G. Eskin, “Microstructure Control in Ingots of Aluminum Alloys with an Emphasis on Grain Refinement”, Essential Readings in Light Metals pp 354-365, 2013

[11] Enzhao Wang, Tong Gao, Jinfeng Nie, Xiangfa Liu, “Grain refinement limit and mechanical properties of 6063 alloy inoculated by Al–Ti–C (B) master alloys”, Journal of Alloys and Compounds, vol. 594, pp.7-11, 2014.

[12] Qun-Yan Tan, Yan-Hong Wang, “ Treatment Technology of Molten Aluminum Alloy ”,School of Mechanical Engineering, North China University of Water Conservancy and Electric Power, 2007

[13] Geoffrey K. Sigworth, Timothy A. Kuhn,“Grain Refinement of Aluminum Casting Alloys”, International Journal of Metalcasting, vol. 1, pp.31-40, 2007.

[14] 台灣穗高科技股份有限公司網址 : https://www.hodakatec.com/zh-tw

[15] 王派文,“除渣與除氣處理對於鋁合金品質的影響”,國立中央大學
機械工程研究所,2001年6月

[16] 美國SPECTRO 網址: https://www.spectro.com/products/optical-emission-spectroscopy/spectrolab-metal-analysis

[17] 加拿大ABB 網址: https://www.abb.com/products/measurement-products/analytical

[18] 美國Wagstaff 網址: https://www.wagstaff.com/Wagstaff.htm

[19] H. TANIHATA and T. SUGAWARA and K. MATSUDA, S. IKENO,“ Effect of casting and homogenizing treatment conditions on the formation of Al–Fe–Si intermetallic compounds in 6063 Al–Mg–Si alloys”, Journal of Materials Science, vol. 34, pp.1205-1210, 1999.。

[20] Pradip K. Saha, “Thermodynamics and tribology in aluminum extrusion”, Elsevier Wear, vol. 218, pp.179-190, 1998.

[21] 李輝煌,“田口方法-品質設計的原理與實務”,高立圖書有限公司,2004.