Surface Roughness Of Test Specimen Research Articles

Study on Prediction Model for Cutting Surface Roughness of Hardened GCr15 Bearing Steel

CBN cutting tool is used to cut hardened GCr15 bearing steel. Based on the surface roughness under different cutting parameters, people built the prediction model of surface roughness by Linear Regression algorithm, and carried on the significance test of it, the results show that the surface roughness forecast model set up by linear regression algorithm has a certain reliability and its linear regression equation is significant; among the cutting parameters, cutting speed and feed rate make great impact to the surface roughness and back engagement of the cutting edge has little impact to the surface roughness of test specimen.

An investigation on effects of wire-EDM machining parameters on surface roughness of newly developed DC53 die steel

DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper investigated the effects of machining parameters on surface roughness of wire EDMed DC53 die steel. The investigated machining parameters were pulse-on time, pulse-off time, pulse-peak current, and wire tension. Analysis of variance (ANOVA) technique was used to find out the parameters affecting the surface roughness. Assumptions of ANOVA were discussed and then examined through residual analysis. Quantitative testing methods on residual analysis were employed in place of the typical qualitative testing techniques. Results from ANOVA show that pulse-on time and pulse-peak current are significant variables to surface roughness of wire-EDMed DC53 die steel. The surface roughness of test specimen increased as these two variables increased.

An experimental investigation of thermal contact conductance of stainless steel at low temperatures

An investigation is carried out to study the effects of surface topography and interfacial temperature on the thermal contact conductance of the pressed stainless steel 304 contacts in the range 125–210 K and 1–7 MPa. The surface roughness of test specimens is between 1.5 μm and 17.6 μm. A theoretical model is used to predict the results and gives a reasonable agreement. The combined effect of phonon conductivity and electronic conductivity to thermal conductivity at low temperatures is described using a proposed correlation. The small contact conductance at low temperatures can ascribe to the decreased thermal conductivity and the increased hardness. It is demonstrated that rms roughness and mean absolute slope are both needed for evaluating contact heat transfer.

An experimental investigation of thermal contact conductance across bolted joints

Abstract An experimental study of thermal contact conductance was conducted with pairs of aluminum alloy (6061-T6) specimens jointed by bolts. The individual aluminum samples have a square cross-section ( 63.5 mm × 63.5 mm ) and a height of 50 mm. Three different bolt patterns were adopted in this study, including single-bolt, 4-bolt, and 8-bolt configurations. The bolt–shaft diameters were 3, 5, and 8 mm, and the torque applied on each bolt was between 1 and 10 N m. The heat flux through the test specimens ranged from 4 to 20 kW/m 2 . The interfacial contact pressure of bolt-jointed specimens was determined by a pressure-measuring film inserted between samples. Results show that the interfacial contact pressure increases with an increase of either the applied torque or the number of bolts. The interfacial temperature difference across the junction was substantially reduced for bolt-jointed specimens, when compared with two superimposed samples without bolts. With the same bolt number, the variation of bolt–shaft diameter from 5 to 8 mm yields nearly no influence on the thermal contact conductance. However, when the size of bolt was kept constant the thermal contact conductance of samples jointed by 8 bolts was greatly larger than that of 4-bolt samples. The increase of contact surface roughness of test specimens leads to a decrease of the thermal contact conductance. When an RTV silicon layer was used as the interstitial material, the total joint conductance of Al/RTV/Al was much lower than the contact conductance of bare aluminum contact. The total joint conductance of Al/RTV/Al was increased with a decrease of the thickness of RTV silicon layers.