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Öğe Comparison of stability of absorbable and titanium plate and screw fixation for sagittal split ramus osteotomy(CHURCHILL LIVINGSTONE, 2004) Dolanmaz, D; Uckan, S; Isik, K; Saglam, HSix unembalmed adult sheep mandibles were stripped of all soft tissues and sectioned at the midline. Each side had a sagittal split ramus osteotomy (SSRO) and was advanced 5 mm. Six of the hemimandibles were fixed with four-hole extended titanium miniplates and titanium screws, and the other six were fixed with four-hole extended absorbable plates and absorbable screws. At[ specimens were mounted in a servohydraulic testing unit, and a range of forces (0-140 N) was applied. Displacement of each proximal segment was recorded at 1 ON increments from 0 to 140 N. Values for the two groups were compared using the Mann-Whitney U-test, and significant differences in displacement were seen only at loads between 10 and 50 N. The results indicate that when absorbable miniptates are used intermaxillary fixation may be necessary to stabilise the bony fragments in the early postoperative period. (C) 2003 The British Association of Oral. and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.Öğe An experimental investigation as to the effect of cutting parameters on roundness error and surface roughness in cylindrical grinding(TAYLOR & FRANCIS LTD, 2005) Saglam, H; Unsacar, F; Yaldiz, SThis paper presents the results of an experimental investigation as to the effects of grinding parameters on roundness error and surface roughness in cylindrical grinding. Many variables including the wheel materials, wheel loading and dressing, workpiece metallurgy, work drive mechanisms, work holding methods, coolant types, feeds and speeds, machine stiffness and age, surface conditions, centre conditions, floor vibrations all influence the quality of ground parts. However, the composite sum of these grinding parameters creates static and dynamic forces. It is obvious that the roundness error and surface roughness are created by many parameters, but in this study, only the effects of the depth of cut, work speed and feed rate which create the grinding forces in cylindrical grinding are investigated. The grinding experiments were planned according to the principles of orthogonal arrays (OAs), developed by Taguchi, and were performed so as to understand the effects of these parameters on roundness error and surface roughness. The experimental data was analysed by using statistical tools: the percent contribution from an analysis of variance ( ANOVA) and the correlation between machining parameters with roundness error ( R) and also surface roughness (Ra). Roundness was found to be the most related with the cutting speed, grinding force and depth of cut, while surface roughness is related to feed rate and work speed.Öğe Investigation of the effect of rake angle and approaching angle on main cutting force and tool tip temperature(ELSEVIER SCI LTD, 2006) Saglam, H; Unsacar, F; Yaldiz, SThis paper deals with the comparison of measured and calculated results of cutting force components and temperature variation generated on the tool tip in turning for different cutting parameters and different tools having various tool geometries while machining AISI 1040 steel hardened at HRc 40. The geometric variables (approaching angle and rake angle) of the tool were changed using selected cutting parameters; thus, the cutting force components and temperature variations on tool face (in secondary shear zone) were determined. The selected cutting variables and the tools in different geometries were tested practically under workshop conditions. in this way, the essential information about the validity of selected values was obtained. During the tests, the depth of cut and cutting speed were kept constant and each test was conducted with a sharp uncoated tool insert. For making a comparison, the main cutting force/tangential force component for different cutting parameters and tool geometries were calculated by Kienzle approach and the temperature values were calculated based on orthogonal cutting mechanism. Finally, the effects of cutting parameters and tool geometry on cutting forces and tool tip temperature were analysed. The average deviation between measured and calculated force results were found as 0.37%. The cutting force signals and temperature values provided extensive data to analyse the orthogonal cutting process. (c) 2005 Elsevier Ltd. All rights reserved.Öğe Tool condition monitoring in milling based on cutting forces by a neural network(TAYLOR & FRANCIS LTD, 2003) Saglam, H; Unuvar, AAutomated machining systems require reliable online monitoring processes. The application of a multilayered neural network for tool condition monitoring in face milling is introduced and evaluated against cutting force data. The work uses the back-propagation algorithm for training neural network of 5 x 10 x 2 architecture. An artificial neural network was used for feature selection in order to estimate flank wear (Vb) and surface roughness (Ra) during the milling operation. The relationship of cutting parameters with Vb and Ra was established. The sensor selection using statistical methods based on the experimental data helps in determining the average effect of each factor on the performance of the neural network model. This model, including cutting speed, feed rate, depth of cut and two cutting force components (feed force and vertical Z-axis force), presents a close estimation of Vb and Ra. Therefore, the neural network with parallel computation ability provides a possibility for setting up intelligent sensor systems.
