Precision Engineering 36 (2012) 168–174 Contents lists available at ScienceDirect Precision Engineering j o ur nal homep age: www.elsevier.com/locate/precision Technical note Novel micro deep drilling using micro long ﬂat drill with ultrasonic vibration Muhammad Aziz a,∗ , Osamu Ohnishi b , Hiromichi Onikura b a Solution Research Lab., Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan b Department of Intelligent Machinery and Systems, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan a r t i c l e i n f o Article history: Received 2 June 2011 Received in revised form 4 July 2011 Accepted 19 July 2011 Available online 23 July 2011 Keywords: Micro long ﬂat drill Micro deep drilling Web thickness Ultrasonic vibration Step feeding a b s t r a c t This paper highlights the development of micro long ﬂat drills with nominal diameter and ﬂute length of 20 m and 200 m, respectively, by precision grinding. Furthermore, it also covers the evaluation of the developed micro long ﬂat drill in micro deep drilling. Micro long ﬂat drills were made of ultra-ﬁne grained cemented carbide containing WC particles with an average particle diameter of 90 nm. First, the study focused on establishing the optimal web thickness of micro long ﬂat drill showing the best performance in micro deep drilling. In drilling experiment, observation was conducted with the aim of ﬁnding the best conditions and method of micro deep drilling into both duralumin and stainless steel workpieces. This observation included the applications of ultrasonic vibration (USV) and step feeding method. The study proved that there was an optimum web thickness resulting in the best drilling performance. Furthermore, the application of USV during drilling could lead to a longer tool life signiﬁcantly. However, there was no improvement of drilling performance in drilling with step feeding. © 2011 Elsevier Inc. All rights reserved. 1. Introduction A fast growing of product miniaturization requires a very pre- cise manufacturing technology. In the ﬁeld of micro machining, micro drilling still stands as the most popular machining process for product manufacturing. There are some methods of micro drilling such as ion beam machining, laser machining, EDM, conventional machining, etc. Each of them has its own superiorities upon other and also its limit concerning the machining capability, cost, etc. Conventional machining was chosen in this study because of its practical use, cheaper devising equipment, shorter machining time, and higher precision [1–4]. Unfortunately, micro machining is not an easy machining pro- cess due to poor stiffness of the tool, difﬁcult burr removal, difﬁcult accurate-positioning, etc. Hence, it is necessary to develop an inno- vative method and/or tool having high performance during micro machining. This study focuses on the idea of micro deep hole drilling with high machining accuracy but low machining cost. Hence, a micro long ﬂat drill was proposed and its performance in micro deep drilling was observed. The objectives of this study are, ﬁrst, ﬁnding the optimal shape of the proposed micro long ﬂat drill regarding the effect of web thickness on tool life, chip removal capability and wear growth. Tool life relates to the capability of the tool to produce number of holes properly without any signiﬁcant tool wear or breakage. Second, the drilling capability of micro long ∗ Corresponding author. Tel.: +81 3 5734 3809; fax: +81 3 5734 3559. E-mail address: maziz@ssr.titech.ac.jp (M. Aziz). ﬂat drill was observed in some different drilling conditions includ- ing the application of ultrasonic vibration (USV) and step feeding method to ﬁnd the optimal conditions for drilling. This study also aims at clarifying the effect of USV and the condition of tool wear during drilling. Furthermore, workpieces which were made of dura- lumin (Al2017) and stainless steel (SUS304) were selected due to their broad use in industry. USV which is applied whether on the machining tool or workpiece during micro machining can improve the machining performance and efﬁciency [5–7]. Deyuan and Lijiang [8] have observed the effect of USV in drilling and they found that the appli- cation of USV in machining could increase the rigidity of the drill and reduce the extent of drill skidding. Chang and Bone [9] found that the application of USV in suitable condition can reduce the burr height and width in comparison to conventional drilling. Liu et al. [10] explained that USV which is applied during machining can bring a lubrication effect that reduces the cutting force. As the result, longer tool life can be achieved. On the other hand, the addi- tional oscillation to the drill causes a sawing tooth-like trajectory at the drill top (cutting edges). Thus, drilling assisted by USV can also be seen as drilling overlapped with oscillations by making use of high frequency oscillation [11]. Unfortunately, there is a lack of study concerning the effect of USV during micro machining, especially micro deep drilling. This study focuses on new method of micro deep drilling with newly developed micro long ﬂat drill and also its combination with USV in micro deep drilling. The latter includes the inﬂuence of USV to drilling force, tool life and tool wear of the developed micro long ﬂat drill. 0141-6359/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.precisioneng.2011.07.010