THE CUTTING PERFORMANCE AND TRIBOLOGICAL CHARACTERISTICS OF SYNTHETIC ESTER LUBRICANTS SUITABLE FOR MQL MACHINING

本研究的目的是了解合成酯类润滑剂的作用机理，适合MQL加工的摩擦学特性和切削性能的调查。本研究的主要结果和结论如下.合成酯的摩擦学性能评价通过对适用于MQL加工的酯的调查，采用基本摩擦试验研究了这些酯的润滑性能，发现一个分子中酯键较多的酯具有较好的润滑性，并且这种趋势在较高的滑动速度下更为突出.通过实际MQL切削试验评价切削性能通过车削合金钢的实际MQL切削试验表明，润滑性较好的酯具有较高的切削性能。对一些难切削材料不锈钢的车削试验也表明，MQL加工可以提高刀具寿命，并且在低切削速度范围内，可以降低切削阻力。此外，MQL端铣铝合金呈现出上级的表面光洁度粗糙度，通过干和空气吹端铣操作获得。吸附特性对酯润滑行为的影响研究了各种气体在新生金属表面的吸附行为，证实氧的吸附作用最大，如果氧和酯同时存在，它们吸附形成的润滑膜可以反映出氧化物和一部分酯的作用。此外，氧气的吸附对钢的切割提供了较好的影响，而在切割铝合金时，氧气的吸附导致性能降低。

The purpose of this study is to understand the action mechanism of synthetic ester lubricants suitable for MQL machining by investigating their tribological characteristics and cutting performance. The main results and conclusions of this study are as follows.1. Tribological characteristics evaluation of synthetic estersAccording to a survey of suitable esters for MQL machining, this study investigated the lubricating characteristics of those esters by a basic friction test and found that an ester having more ester bonds in one molecule showed the better lubricity and such trend was prominent at higher sliding speed.2. Evaluation of cutting performance by practical MQL machining testsThe practical MQL machining of alloy steels by turning illustrated an ester showing the better lubricity provided the higher cutting performance. The turning tests of some stainless steels categorized as a difficult-to-cut material also demonstrated that MQL machining could improve the tool life and, in the range of low cutting speeds, could decrease the cutting resistance. Further, MQL end-milling of an aluminum alloy presented superior surface finish roughness to that obtained by dry and air blow end-milling operations.3. Influences of adsorption characteristics on the lubricating behavior of estersThe investigation regarding the adsorption behavior of various gases onto nascent metal surfaces verified that the adsorbing action of oxygen is most dominant and, if oxygen and an ester existed together, the lubricating film formed by their adsorption could reveal the action resulted from both the oxide and a part derived from the ester. sing a controlled atmospheres cutting apparatus, In addition, the adsorption of oxygen provided a preferable influence on cutting steel, whereas it caused low performance when cutting aluminum alloy.