Machining of Composite Materials: Mechanics, Quality and Coolant Strategies

由于复合材料在不同行业的广泛需求，复合材料得到了长足的研究和发展。金属基复合材料(MMC)自20世纪80年代初由丰田公司试制以来，在汽车、航空航天等领域得到了广泛的应用。MMCs具有许多优点，包括更高的比强度和刚度、更轻的重量、更好的耐磨性和抗冲击损伤、更低的热膨胀系数、可定制的导热系数和更好的减振。与传统的金属合金相比，金属基复合材料具有更低的生命周期成本，并可替代一些关键或战略性材料。在一些应用中，金属基复合材料被用来替代包括铝合金、铁合金、钛合金和聚合物基复合材料在内的整体式材料。为了在工程系统中广泛应用MMCs替代整体材料，人们努力采用铸造或热锻造的方法来生产MMCs。然而，生成的近净形状产品仍需加工成设计的形状和尺寸。早些时候进行了深入的研究，以调查金属基复合材料的可加工性，包括申请人在过去几年进行的研究。申请人以前的一项工作和对已发表文献的回顾表明，这些材料的传统切割会导致过度的刀具磨损和可能的亚表面损坏，从而导致切割成本和生产时间的增加。亚表面损伤评估对于遭受疲劳的机械加工部件是至关重要的，特别是在航空航天等关键应用中。鉴于这些材料的应用越来越广泛，需要对它们的加工表面完整性进行详细的研究，并提高它们的切割加工效率。此外，还需要关于金属去除过程中钢筋的相互作用以及它如何影响已加工表面完整性的详细信息。 鉴于这些需求，本研究将侧重于与加工金属基复合材料相关的挑战，包括表面完整性问题。此外，还将探索和开发使用具有最小润滑量(MQL)的新型纳米流体。将研究纳米添加剂在改善润滑和热特性方面的作用。基于纳米流体的MQL是申请人最近探索的一种加工钛、镍等航空航天合金的新技术。该技术在金属基复合材料加工中的成功应用，无疑将促进纳米流体润滑剂的广泛应用，使纳米流体润滑剂不仅成为一种有效的润滑剂，而且与MQL一起使用，将成为一种可持续的环境友好技术。

Composite materials have received considerable research and development due to wide spread demands in different industry. Metal Matrix Composites ( MMC) have been widely utilized in many applications including automotive and aerospace since the early trials by Toyota in the early 1980s. MMCs offer several advantages including higher specific strength and stiffness, weight reduction, better resistance to wear and impact damage, a lower thermal coefficient of expansion, tailorable thermal conductivity, and better vibration damping. In comparison to conventional metal alloys, MMCs offers lower life-cycle costs and replace some critical or strategic materials. MMCs are intended to substitute monolithic materials including aluminium alloys, ferrous alloys, titanium alloys and polymer based composites in several applications. In order to have a wide spread MMCs substitution for monolithic materials in engineering system, efforts have been made to produce MMCs by casting, or hot forging. However, the generated near net-shape products still have to be machined into the designed shape and dimension. Intensive research to investigate the machinability of the MMCs was conducted earlier, including the research performed by the applicant during the past few years. A previous work of the applicant and a review of the published literature indicate that the conventional cutting of these materials leads to excessive tool wear and possible subsurface damage, thereby resulting in increased cutting cost and production time. Subsurface damage assessment is critical for machined components subjected to fatigue, especially in critical application such as aerospace. In view of the growing applications of these materials, detailed study of their machined surface integrity and improving of their cutting process efficiency is required. In addition, detailed information about the reinforcement's interaction during the metal removal and how it affects the machined surface integrity is required. In view these needs, this study will focus on challenges associated with machining MMCs including surface integrity issues. Also, the use of new nano-fluid with Minimum Quantity Lubrication (MQL) will be explored and developed. The role of nano-additives in improving lubrication and heat characteristics will be studied. The nano-fluid based MQL is a new technology which was recently explored by the applicant for machining aerospace alloys including titanium and inconel . The successful use of this technology during machining MMCs will with no doubt facilitate the wide spread applications of MMCs and present the nano-fluid based lubricant not only as effective lubricant but also as a sustainable environmentally friendly technique when it is utilized with MQL.