Rough cutting of germanium with polycrystalline diamond tools

Yergök, Çağlar
Germanium is a brittle semi-metal, used for lenses and windows in Thermal Imaging Systems since it transmits infrared energy in the 2 µm - 12 µm wavelength range at peak. In this thesis study, polycrystalline diamond is used as cutting tool material to machine germanium. Diamond is the hardest, most abrasion-resistant material and polycrystalline diamond is produced by compacting small diamond particles under high pressure and temperature conditions, which results more homogeneous, improved strength and a durable material. However, slightly reduced hardness is obtained when compared with natural diamond. Different from finish cutting, rough cutting, performed before finishing, is used to remove most of the work-piece material. During rough cutting, surface roughness is still an important concern, since it affects the finishing operations. Roughness of the surface of product is affected by a number of factors such as cutting speed, depth of cut, feed rate as cutting parameters, and also rake angle as tool geometry parameter. In the thesis, the optimum cutting and tool geometry parameters are investigated by experimental studies for rough cutting of germanium with polycrystalline diamond tools. Single Point Diamond Turning Machine is used for rough cutting, and the roughness values of the optical surfaces are measured by White Light Interferometer. Experiments are designed by making use of “Full Factorial” and “Box-Behnken” design methods at different levels considering cutting parameters as cutting speed, depth of cut, feed rate and tool geometry parameter as rake angle.


An experimental study on single crystal diamond turning of optical quality silicon
Çalı, Serdal; Gökler, Mustafa İlhan; Department of Mechanical Engineering (2008)
Silicon is commonly used in infrared (IR) imaging systems. The surface quality is an important issue in optics manufacturing since surface roughness affects optical performance of imaging systems. Surface quality of an optical component is determined by number of factor, including cutting parameters; cutting speed, depth of cut and feed in radial direction. In this thesis, an experimental study has been performed to investigate the relation between cutting parameters and average roughness of the surface of ...
Design and implementation of an open-source optically stimulated luminescence measurement system
Maraba, Diren; Bulur, Enver; Department of Physics (2017)
Optically Stimulated Luminescence (OSL) is the light emission from an irradiated solid (insulator or a wide band gap semiconductor) upon illumination with light of suitable wavelength. Although the phenomenon has been known for a long time, OSL has emerged as a practically applicable dosimetry technique in the past two decades. Recently introduced materials like alumina and beryllia have found use in the field of radiation dosimetry. The purpose of this study is to design and construct a simple multi-sample...
Optimizing heat exchanger parameters of a joulethomson cryogenic cooler to improve the cooling performance
Baki, Murat; Okutucu Özyurt, Hanife Tuba; Sert, Cüneyt; Department of Mechanical Engineering (2018)
Cryocoolers are one of the key components of cooled infrared (IR) imaging systems, where it is not possible to form an image in photon detectors without decreasing the sensor temperature to cryogenic temperatures. In detector cooling applications where low cool down times, small size and weight are required, mostly Joule Thomson (JT) cryocoolers are preferred. The aim of this study is to analyze the heat exchanger of a JT cryocooler operating with argon as the working gas, numerically and optimize its desig...
Short term variations of total electron content (TEC) fitting to a regional GPS network over the Kingdom of Saudi Arabia (KSA)
Alothman, A. O.; Alsubaie, M. A.; Ayhan, M. E. (Elsevier BV, 2011-09-01)
The ionosphere is a dispersive medium for radio waves with the refractive index which is a function of frequency and total electron content (TEC). TEC has a strong diurnal variation in addition to monthly, seasonal and solar cycle variations and small and large scale irregularities. Dual frequency GPS observations can be utilized to obtain TEC and investigate its spatial and temporal variations. We here studied short term TEC variations over the Kingdom of Saudi Arabia (KSA). A regional GPS network is forme...
Fabrication of microfluidic devices for dielectrophoretic and acoustophoretic applications using high precision machining
Soheila, Zenaili; Çetin, Barbaros; Özer, Mehmet Bülent; Süleyman, Büyükkoçak (2014-07-03)
In this study, the fabrication of microfluidic devices for dielectrophoretic and acoustophoretic based applications with high-precision CNC machining has been presented. For both devices, molds out of stainless steel have been fabricated, and polymer molding is implemented. For dielectrophoretic device, the metal electrodes have been fabricated using high-precision machining and embedded into the device during the molding process. For acoustophoretic device, piezoelectric slides have been embedded into the ...
Citation Formats
Ç. Yergök, “Rough cutting of germanium with polycrystalline diamond tools,” M.S. - Master of Science, Middle East Technical University, 2010.