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 ...
Conduction based compact thermal modeling for thermal analysis of electronic components
Ocak, Mustafa; Sert, Cüneyt; Department of Mechanical Engineering (2010)
Conduction based compact thermal modeling of DC/DC converters, which are electronic components commonly used in military applications, are investigated. Three carefully designed numerical case studies are carried out at component, board and system levels using ICEPAK software. Experiments are conducted to gather temperature data that can be used to study compact thermal models (CTMs) with different levels of simplification. In the first (component level) problem a series of conduction based CTMs are generat...
Mixed-mode fracture analysis of orthotropic functionally graded materials
Sarıkaya, Duygu; Dağ, Serkan; Department of Mechanical Engineering (2005)
Functionally graded materials processed by the thermal spray techniques such as electron beam physical vapor deposition and plasma spray forming are known to have an orthotropic structure with reduced mechanical properties. Debonding related failures in these types of material systems occur due to embedded cracks that are perpendicular to the direction of the material property gradation. These cracks are inherently under mixed-mode loading and fracture analysis requires the extraction of the modes I and II ...
Performance anallysis of an intermediate temperature solid oxide fuel cell
Timurkutluk, Bora; Tarı, İlker; Department of Mechanical Engineering (2007)
An intermediate temperature solid oxide fuel cell (SOFC) is developed and its performance is investigated experimentally and theoretically. In the experimental program, a gadolinium doped ceria based membrane electrode group is developed with the tape casting and screen printing methodology and characterized. An experimental setup is devised for the performance measurement of SOFCs and the performance of produced cells is investigated over a range of parameters including the electrolyte thickness, the sinte...
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...
Citation Formats
Ç. Yergök, “Rough cutting of germanium with polycrystalline diamond tools,” M.S. - Master of Science, Middle East Technical University, 2010.