多模穴共射射出成型系統與技術(Co-injection multi-cavity system)已經廣泛地應用於汽車、結構件、日常生活等許多產品。然而，由於影響因子眾多包括：產品與模具設計、材料特性、皮層/核心層比例(skin/core ratio)、以及操作條件，造就了多模穴共射系統非常複雜。共射射出成型製程是將兩種不同材料成型於同一產品上，當此製程使用於多模穴量產時，容易因兩種塑膠流動性質不同及塑膠競流效應造成每一模穴中材料分佈情形各有不同，導致產品良率不佳。本研究中之系統為非平衡流道系統，其影響效應非常大，僅透過調整成型參數來改善核心層材料(core materials)之分佈情形之效果並不明顯，故本研究以探討模穴幾何變異為主，成型參數改變為輔，對於產品良率不佳之問題進行優化與改善。明確而言，本研究利用Moldex3D R14模流分析軟體進行分離式不平衡多模穴系統，探索發現此系統最大問題為模具間極度不平衡問題，進而導致核心層材料分佈不均問題；經深入探究發現當皮層/核心層比例固定為70/30時，不論是嘗試改變不同操作條件或使用不同材料，都無法有效改善此等問題，因為產品的設計(模穴設計)主導了整個產品的成型機制。為此，本研究特別引入連通區域建構結合型多模穴系統，從充填初始就改變流場，進而改善模穴間極度不平衡問題與核心層材料分佈不均問題。具體而言，從原始設計分離式不平衡多模穴系統至改良式結合型多模穴系統之演進，我們確認透過模穴幾何改變可使平衡度的表現有良好的提升，特別是在模穴1的部份，有幾乎100%的平衡度提升，且三個模穴相對平衡度差距都是在都5%以下的高品質。 Multi-cavity co-injection molding has been used in daily accessories, car parts, and structural-reinforcement product. However, there are too many combinations of designs, materials, core/skin ratio, and process condition, how to have suitable control of co-injection is very challenge. The manufacturing process of co-injection multi-cavity system is to mix two kinds of material and form it into another product. When we use this method to manufacture products, it often caused different kinds of distribution between each cavity because of its properties and the effect of flow，so the quality of product is poor. Because of the system in this research is unbalance, the important operation parameters are quite large. It is very difficult to make the suitable control by adjusting some operation conditions. Hence, in this study, first, we have applied Moldex3D software to analyze the separated multi-cavity system. The results showed that, at fixed skin/core ratio of 70/30, the crucial problem of the inter-cavity imbalance is almost unsolved by modified various operation conditions or even by changing materials. This inter-cavity imbalance property will further induce poor core material distribution for final co-injection product. To solve this problem, we have introduced some connection area between cavities based on flow-lead concept. The basic idea is that through the modification of the flow field at the early age of filling stage, the inter-cavity balance can be improved significantly. The core material distribution of the system can be further improved. Based on the final revised design, the inter-cavity balance degree has been improved.
