Abstract:
Micro iholes iwith internal features are widely used as spray iholes, icooling iholes, iheat ishields, ifuel iinjection inozzles, iweapons, iaerospace, iscrew idrill istator iof ioil iand igas idrilling icomponents inowadays, iwhich iare iusually irequired ito ibe iwith ihigh aspect ratio (over 200:1) is iimpossible ito ibe imachined iby conventional techniques. This report deals with the process which was conducted to assess high depth to diameter ratio micro-hole drilling on difficult-to-machine imaterial. iHowever, ielectrochemical imachining i(ECM) ihas ithe iunique iadvantages iof ihigh iefficiency, ihigh isurface iquality, ino istress iand ino icathode iwear iin imachining idifficult-to-cut iconductive imaterials. iiAn iECM iBased iShaped itube ielectrolytic imachining i(STEM) imethod iis iused ifor imanufacturing ihigh iaspect iratio ideep imicro holes in this report. It is found that STEM with various tool modifications, is a feasible, stable and high-efficiency machining imethod ifor iproducing multiple holes in a single pass with depth ito idiameter iratio of around 300:1 with internal ridges.
The present study focuses on investigating the effect of four operating parameters voltage, electrolyte concentration, feedrate and flowrate and their contribution using ANOVA approach on the performance of STEM process, for the two responses namely MRR, hole taper have been done with the help of Qualitek-4 software. Experiments shows that good holes can be obtained by a combination of low voltage and comparatively high feedrate. A good, uniform hole with an aspect ratio of 18.2 was obtained in HSS workpiece at voltage, electrolyte flowrate, tool feedrate and electrolyte concentration of 18V, 120ml/min, 0.35mm/min and 8% concentration (v/v) respectively. Results also point to the need for using dummy strips above and below the workpiece for obtaining uniform hole diameter, specially at the ends.
