K. Sadashivappa

Bio: K. Sadashivappa is an academic researcher from Bapuji Institute of Engineering & Technology. The author has contributed to research in topics: Axial piston pump & Radial piston pump. The author has an hindex of 2, co-authored 2 publications receiving 40 citations.

Nonconventional cutting of plate glass using hot air jet: experimental studies

Abstract: Glass is an important engineering material used in several applications because of its attractive look, chemical stability towards environment, nonporosity, and transparent nature. Its application is widely found in optomechatronic systems, windows of buildings, art work, etc. Glass cutting is the first step in the fabrication for any of its applications. Conventionally, plate glass (soda lime glass) is cut by a diamond point tool or a diamond wheel. The cut surfaces by this method are rough and wavy. Microcracks, which affect the life and quality of glass, may develop during cutting. It is difficult to cut nonstraight profiles by the conventional method and glass wastage is more. Curved profiles cannot be cut in a single step. Recently, glass cutting using laser and abrasive waterjet have been developed. Laser cutting is very costly, unsafe and leaves a heated-affected zone. Researchers have used laser cutting on glasses of thicknesses lesser than 1 mm. Abrasive waterjet requires de-ionized very high pressure water with entrained garnet abrasive. This method produces rough cut surfaces and causes wear of diamond nozzles. A novel method is developed which uses a low cost, simple, hot air jet to cut any complex profile with ease. Experimental studies are conducted to determine the variation of the cutting speed for various values of the stand-off distance, glass thickness, air temperature, and air flow rates. Glasses in the thickness range of 2–20 mm are used for the experiments. The roughness of the cut surfaces using the hot air jet and the diamond point tool is compared. The new method has produced cut surfaces of relatively higher surface finish.

Piston eccentricity and friction force measurement in a hydraulic cylinder in dynamic conditions considering the form deviations on a piston

Abstract: Geometrical imperfections on pistons cause an asymmetric pressure distribution in the clearance between the piston and cylinder bore. Due to this, the piston attains different eccentricity positions during a stroke. The eccentricity of the piston affects the performance of the cylinder by influencing the frictional and leakage aspects. A compact mechatronic test rig is designed and fabricated to measure the piston eccentricity and friction in a dynamic condition. Pistons of defined geometric profiles such as elliptic and three-lobe are fabricated using a machining center. These pistons have been introduced into the test rig. The eccentricity and dynamic friction tests are conducted at various operating conditions and the results are presented and analysed.

Laser glass cutting techniques—A review

Abstract: With the advancement of glass technology in recent times, glass has become one of the most important engineering materials in architectural, medical, automotive, flat panel display, and electronics applications. Desired shape and size of the glass can only be achieved through accurate and precise cutting technique. Laser technology has an advantage over traditional cutting processes for glass due to good quality, surface finish, and high speed of operation. This paper provides a review of all the laser glass cutting techniques discovered in recent work and forms a comparison framework, in particular, their limitations and their current status which would facilitate prospective research and future development.

Picosecond laser cutting and drilling of thin flex glass

Abstract: We investigate the feasibility of cutting and drilling thin flex glass (TFG) substrates using a picosecond laser operating at wavelengths of 1030 nm, 515 nm and 343 nm. 50 μm and 100 μm thick AF32®Eco Thin Glass (Schott AG) sheets are used. The laser processing parameters such as the wavelength, pulse energy, pulse repetition frequency, scan speed and the number of laser passes which are necessary to perform through a cut or to drill a borehole in the TFG substrate are studied in detail. Our results show that the highest effective cutting speeds (220 mm/s for a 50 μm thick TFG substrate and 74 mm/s for a 100 μm thick TFG substrate) are obtained with the 1030 nm wavelength, whereas the 343 nm wavelength provides the best quality cuts. The 515 nm wavelength, meanwhile, can be used to provide relatively good laser cut quality with heat affected zones (HAZ) of

The effect of piston grooves performance in an axial piston pumps via CFD analysis

Abstract: In the design of high pressure piston pumps/motors, some manufacturers use pistons which have grooves being cut along the piston length, while others do not use grooves at all. The present paper clarifies the effect of grooves cut along the pistons surface via studding the effect of the number of grooves and their location over the piston surface. Piston force, torque, leakage, areas where cavitation might appear and piston stability, will be, in the present paper and for a set of piston/grooves configurations, carefully evaluated. A finite volume based Reynolds equation model has been formulated for the piston–cylinder clearance which considers the piston eccentricity and the relative tangential movement between piston and barrel. Different grooves configurations have been evaluated in search of finding minimum leakage, minimum appearance of cavitation and maximum restoring torque. Design instructions to optimize the piston behavior are also given, therefore the information and methodology presented in the present paper, is expected to be used as a designing tool for future machines. The piston/cylinder leakage is considered as laminar under all working conditions. The Fluid used is hydraulic oil ISO 32.

Laser machining of transparent brittle materials: from machining strategies to applications

Abstract: Transparent brittle materials such as glass and sapphire are widely concerned and applied in consumer electronics, optoelectronic devices, etc. due to their excellent physical and chemical stability and good transparency. Growing re-search attention has been paid to developing novel methods for high-precision and high-quality machining of transparent brittle materials in the past few decades. Among the various techniques, laser machining has been proved to be an effective and flexible way to process all kinds of transparent brittle materials. In this review, a series of laser machining methods, e.g. laser full cutting, laser scribing, laser stealth dicing, laser filament, laser induced backside dry etching (LIBDE), and laser induced backside wet etching (LIBWE) are summarized. Additionally, applications of these techniques in micromachining, drilling and cutting, and patterning are introduced in detail. Current challenges and future prospects in this field are also discussed.

Analysis and parametric optimization of abrasive hot air jet machining for glass using taguchi method and utility concept

Abstract: Carrier media plays a major role in removal of material in Abrasive Jet Machining (AJM). In this paper, an attempt has been made to use hot air as carrier media in AJM. Modified Taguchi robust design analysis is employed to determine optimal combination of process parameters. The Analysis Of Variance (ANOVA) is also applied to identify the most significant factor. It can be found that the air temperature is the most significant factor on Material Removal Rate (MRR) and Roughness of machined surface (Ra). It has been observed that there is good agreement between the predicted values and experimental values of optimization. The influence of temperature on MRR and Ra has been discussed. It can be found that at high temperature, there is a sufficient evidence of more plastic deformation accompanied by brittle fracture failure which results in increase of MRR and reduction of roughness.