網球拍射出模具表面抗沾黏處理

摘要：台灣的網球拍產業，從民國50年代開始替國外代工木製的羽毛球拍開始，經歷鐵拍、鋁拍的階段，1978年由從國外引進碳纖維複合材料，開始製造碳拍之後，短短的幾年間，不但淘汰了木製球拍，改變了世界網球拍的產銷結構，成為網球拍王國，而且奠定了台灣在全球複合材料加工技術上重要的地位。在這個打造網球拍王國的過程中，從一開始因緣際會引進一些簡單的複合材料的加工概念，接著在一群技術英雄幾近土法煉鋼的努力開發下，發展出一套最具競爭力的滾筒纏繞法（filament drum winding）用以製造預浸布，再用獨創的吹氣熱壓成型（inner bladder pressure molding）的方式量產球拍，吹氣熱壓成型時膠體會因高溫與模具沾黏，因而影響射出品質。

本研究利用直流磁控濺鍍法在SKD61熱作工具鋼上沉積Ti基鍍膜並加入耐高溫如鎢、鉭、鋁等原子並通入反應性氮等氣體，利用SEM、GID-XRD以及TEM對薄膜的表面形貌、晶體結構及化學鍵結進行分析，最後再以熱反覆實驗測試鍍膜的熱穩定性。結果顯示，Ti基高溫鍍膜能有效提升SKD61基板之耐熱穩定性，經過線上實測在500 ℃溫度下，熱反覆實驗達500次不需使用離形劑可提升稼動率及產品品質。

Abstract: The tennis racket industry of Taiwan originates from the original equipment manufacturing of wooden badminton rackets in the 1960s, then technologies of Taiwan became matured and began to manufacture iron and aluminum rackets. In 1978, Taiwan imported carbon fiber composite material to manufacture carbon tennis rackets. Not only eliminating the wooden tennis racket within a few years, Taiwan also changed the global production-sale infrastructure of the tennis racket, and became the “tennis racket kingdom” and established the key position of machining technology of global composite materials.

In establishing the tennis racket kingdom of Taiwan, the machining concept of simple composite materials and use of native technologies led to the development of the most competitive filament drum winding method to manufacture the pre-immersion cloth and the innovative inner bladder pressure molding method to quantitative production of the tennis racket. The inner bladder pressure molding method has disadvantages which affect the quality of the injection products due to high temperature mold sticking of the plastic materials.

This project uses the dc magnetron sputtering method to deposit Ti coating film on the SKD61 hot working tool steel and adds some high temperature resistant atoms such as W, Ta and Al as well as reactive nitrogen gas. Surface morphology, crystalline structure and chemical bonding of the coating could be analyzed by using SEM, GID-XRD and TEM. Finally, thermal repetition testing was used to test the thermal stability of the coating. Experimental results show that Ti-based coating film could effectively promote the 500 °C resistance thermal stability of the SKD61 substrate. After 500 °C in-line testing, thermal repetition life could reach 500 times without using releasing agents and promoted the production time ratio and product quality.

關鍵詞：物理氣相層積、磁控濺鍍、抗沾粘

Keywords：Physical Vapor Deposition (PVD), Magnetron Sputtering, Anti-Sticking

前言
網球拍成形模具材質為SKD61，在高溫（≧500 ℃）射出成形時，膠體在模具的流道會與模具產生沾黏，造成膠體流動速度變慢甚至阻塞，造成成品良率下降，當模具有沾黏情形，生產線須停工將模具下架清除沾黏處，會造成稼動率降低，提高廠商生產成本。為克服射出模具沾粘問題。在製造射出模具時，除了適當的模具方案設計外，尚有兩個選項：模具材料的選用及模具表面的鍍膜。但無論何種選項皆會影響尺寸和表面精度，及模具的使用壽命。在反覆開模/關模成型過程，模具亦受到高/低溫度熱衝擊，會造成模具尺寸變形及表面鍍膜剝落。因此如何選擇適當的模具材料及鍍膜是非常重要的。由於射出模具在膠體射出過程中處於高溫環境，膠體的黏性增加，流動性降低，容易與鍍膜或模具材料產生反應，產生沾黏及阻塞，不僅影響網球拍的表面品質，亦是降低射出模具壽命的重要影響因素。而現今，射出模具常用於模具上鍍膜材料大部分以貴金屬為主，如Pt、Ir…等貴金屬或其化合物[1-9]，也有利用其他元素如Ti、Ta、Cr、Si等其化合物或與貴金屬化合做為中介層或保護層，來改善鍍膜之性質。因此，本研究計畫將配合模具壽命之目標需求，選擇適當的模具材料，建立適當的鍍膜材料與技術，以提高模具的使用壽命、降低製作成本，以及提供高可靠度及規格化的元件，並符合網球拍射出模具產業化的應用趨勢。