Abstract

In recent years, demand of titanium alloy (Ti6Al4V) in various industries especially aerospace industries drastically increased. Several exceptional properties of titanium alloy that contribute to its popularity include high compressive and tensile strength, fracture toughness oxidation resistance and high strength-to-weight ratio. However, due to these superior properties, titanium alloys are categorized as hard-to-machine materials. The drilling process is accounted for roughly 40%−60% of material removal processes of an aeronautical product. Drilling processes for titanium alloys are categorized into conventional method (twist drilling) and unconventional method (rotary ultrasonic machining [RUM] drilling, laser drilling and electron discharge machining [EDM] drilling). This research aims to identify mechanisms and limitations of each drilling method applicable on titanium alloys. In addition, processing parameters affecting performance measures of each drilling method are discussed. The main problem associated with conventional twist drilling is extreme processing temperature, resulting in rapid tool wear and extensive burrs formation. These issues cause the cost for titanium alloy drilling to be relatively high as compared with twist drilling of other materials. To minimize these issues, researchers have developed several unconventional drilling methods, aiming to minimize issues found in conventional twist drilling.

摘要

近年来，各行业尤其是航天工业对钛合金（Ti6Al4V）的需求急剧增加。钛合金的几项卓越性能使其广受欢迎，包括高压缩和拉伸强度、断裂韧性、抗氧化性和高强度重量比。然而，由于这些优越的性能，钛合金被归类为难加工材料。钻孔过程约占航空产品材料去除过程的 40%-60%。钛合金的钻孔工艺分为常规方法（扭曲钻孔）和非常规方法（旋转超声加工 [RUM] 钻孔、激光钻孔和电子放电加工 [EDM] 钻孔）。本研究旨在确定适用于钛合金的每种钻孔方法的机制和局限性。此外，还讨论了影响每种钻孔方法性能指标的工艺参数。与传统麻花钻相关的主要问题是极端的加工温度，导致刀具快速磨损和大量毛刺形成。这些问题导致钛合金钻孔与其他材料的麻花钻孔相比成本相对较高。为了尽量减少这些问题，研究人员开发了几种非常规钻孔方法，旨在尽量减少传统麻花钻孔中发现的问题。与传统麻花钻相关的主要问题是极端的加工温度，导致刀具快速磨损和大量毛刺形成。这些问题导致钛合金钻孔与其他材料的麻花钻孔相比成本相对较高。为了尽量减少这些问题，研究人员开发了几种非常规钻孔方法，旨在尽量减少传统麻花钻孔中发现的问题。与传统麻花钻相关的主要问题是极端的加工温度，导致刀具快速磨损和大量毛刺形成。这些问题导致钛合金钻孔与其他材料的麻花钻孔相比成本相对较高。为了尽量减少这些问题，研究人员开发了几种非常规钻孔方法，旨在尽量减少传统麻花钻孔中发现的问题。